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71
Centre Number
Candidate Number
6620.07R
TIME
2 hours 30 minutes.
INSTRUCTIONS TO CANDIDATES
Write your Centre Number and Candidate Number in the spaces provided at the top of this page.Answer all three questions.Write your answers in the spaces provided.
INFORMATION FOR CANDIDATES
The total mark for this paper is 70.Questions 1 and 2 are practical exercises each worth 25 marks.Question 3 is a planning exercise worth 20 marks.Quality of written communication will be assessed in Question 3.You may not have access to notes, textbooks and other material to assist you.A Periodic Table of elements (including some data) is provided.
For Examiner’s use only
QuestionNumber Marks
Modera-tionMark
1
2
3
TotalMarks
ADVANCEDGeneral Certificate of Education
2011
Chemistry
Assessment Unit A2 3Internal Assessment
Practical Examination 1
[AC231]
TUESDAY 17 MAY, MORNING
6620.07R 2 [Turn over
Teacher Examiner Remark
Mark Check1 Titration exercise
Crystalline ammonium iron(II) sulfate has the formula Fe(NH4)2(SO4)2.nH2O. The symbol n represents the number of molecules of water of crystallisation.
You are provided with:
A solution of ammonium iron(II) sulfate of concentration 31.4 g dm23.
A solution of potassium permanganate of concentration 0.02 mol dm23.
Solutions of 2 mol dm23 sulfuric acid.
Assuming that all the apparatus is clean and dry, you are required to carry out a titration and use your results to determine the value of n.
(a) Give details of the procedure you intend to use. The potassium permanganate solution should be placed in a burette.
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
_____________________________________________________ [6]
6620.07R 3 [Turn over
Teacher Examiner Remark
Mark Check (b) Carry out your procedure. Present your results in a suitable
table and calculate the average titre.
[10]
(c) State the colour change at the end point of your titration.
_________________________ to _________________________ [2]
(d) Write the equation for the reaction of iron(II) ions (Fe21) with acidified permanganate ions (H1/MnO4
2).
_____________________________________________________ [2]
6620.07R 4 [Turn over
Teacher Examiner Remark
Mark Check (e) Calculate the molarity of the ammonium iron(II) sulfate solution.
________________________________________________________
________________________________________________________
_____________________________________________________ [2]
(f) Determine the molar mass of the ammonium iron(II) sulfate and deduce the value of n.
________________________________________________________
________________________________________________________
________________________________________________________
_____________________________________________________ [3]
6620.07R 5 [Turn over
Teacher Examiner Remark
Mark Check2 Observation/deduction
Safety goggles must be worn at all times and care should be exercised during this investigation.
(a) You are provided with a salt, labelled A. Carry out the following tests.
Record your observations in the spaces below.
Test Observation Deduction
1 Describe the appearance of A.
[1] [1]
2 Add a spatula measure of A to approximately 50 cm3 of water and stir.
[2] [1]
3 Add 10 drops of silver nitrate solution to 2 cm3 of the solution of A in a test tube. Allow to stand. [2] [1]
4 Add 5 drops of sodium hydroxide solution to 2 cm3 of the solution of A in a test tube. [1] [1]
5 In a fume cupboard, add 6 cm3 of concentrated ammonia, slowly, to 2 cm3 of the solution of A in a test tube. [3]
No deduction required
6 Add 4 cm3 of concentrated hydrochloric acid to 2 cm3 of the solution of A in a test tube.
[1]
No deduction required
Deduce the name of compound A ______________________ [1]
6620.07R 6 [Turn over
Teacher Examiner Remark
Mark Check (b) Substance B is an organic compound with two functional
groups. Carry out the following tests on B and complete the table.
Test Observation Deduction
1 Describe the appearance of B.
[1] [1]
Below is a description of test 2. Please read this but do not carry out this test.
2 Heat one spatula measure of B in a test tube. Heat gently at first and then more strongly. Test any fumes with a glass rod dipped in concentrated hydrochloric acid.
White smoke
[1]
3 (i) Dissolve 2 spatula measures of B in approximately 20 cm3 of water.
(ii) Use Universal Indicator paper to determine the pH of the solution of B. [1] [1]
4 Add 6 drops of copper(II) sulfate solution, dropwise, to a test tube half-full of a solution of B.
[1] [1]
5 To 3 cm3 of acidified potassium dichromate solution add one spatula measure of B and warm gently.
[1] [1]
6620.07R 7 [Turn over
Teacher Examiner Remark
Mark Check
6620.07R 7 [Turn over
The infra-red and n.m.r. spectra of B are shown below. Note that the molecule of B has made an internal structural rearrangement. Use these spectra and the practical tests to suggest the identity of B.
Infra-red Spectrum
0.75
0.6
0.45
0.3
0.15
4000 3000 2000 1000
Wavenumber (cm�1)
Tra
nsm
ittan
ce
Hydrogen atoms attached to electronegative atoms such as N or O absorb in the region above 3000 cm21. The actual absorption region is affected by acidity and whether the IR spectrum is obtained for the solid or a solution of the substance.
The carbonyl group in ketones absorbs at 1720 cm21. All other compounds containing C=O groups absorb from 1580 to 1800 cm21.
N.m.r. spectrum
8 7 6 5 4 3 2 1 0
Identity of B __________________________________________ [1]
Maximum [25]
6620.07R 8 [Turn over
Teacher Examiner Remark
Mark CheckPlanning exercise
3 Preparation of sodium peroxide, Na2O2.
Sodium peroxide may be prepared by passing dry oxygen over sodium in a “boat” made of aluminium foil which is placed in a combustion tube. The tube is heated until the sodium melts. It is further heated until the sodium burns.
At this stage the heating can be turned down.
After reaction a stream of dry air is passed through the combustion tube. The resulting sodium peroxide is placed in a stoppered bottle and weighed.
The sodium peroxide is obtained as a white solid with a slightly yellow appearance. It reacts readily with water to produce hydrogen peroxide or oxygen depending on the temperature at which the reaction is carried out.
You are required to prepare 1.3 g of sodium peroxide based on the mass of sodium used.
(a) Write an equation, including state symbols, for the reaction of sodium with oxygen to produce sodium peroxide.
_____________________________________________________ [2]
(b) Calculate the mass of sodium needed assuming an 80% yield.
________________________________________________________
________________________________________________________
________________________________________________________
________________________________________________________
_____________________________________________________ [4]
(c) Explain why it is essential that the oxygen, which is passed over the sodium, is dry.
________________________________________________________
_____________________________________________________ [2]
6620.07R 9 [Turn over
Teacher Examiner Remark
Mark Check (d) Draw a labelled diagram of the apparatus used to prepare
sodium peroxide, showing how the oxygen gas may be dried.
[4]
(e) The sodium peroxide may be used to prepare hydrogen peroxide by reacting it with acids at low temperatures. Adding phosphoric (V) acid to sodium peroxide produces disodium hydrogenphosphate, Na2HPO4, which crystallises with twelve molecules of water.
(i) Write an equation for the reaction of phosphoric (V) acid with sodium peroxide.
_________________________________________________ [2]
(ii) Suggest why this method is better than using hydrochloric acid producing sodium chloride, which crystallises without molecules of water, to prepare a concentrated solution of hydrogen peroxide.
____________________________________________________
_________________________________________________ [2]
(f) Sodium peroxide reacts with water at higher temperatures to form sodium hydroxide and oxygen. Describe how you would use GLC to show that oxygen was given off.
________________________________________________________
________________________________________________________
_____________________________________________________ [2]
Quality of written communication [2]
THIS IS THE END OF THE QUESTION PAPER
Permission to reproduce all copyright material has been applied for.In some cases, efforts to contact copyright holders may have been unsuccessful and CCEAwill be happy to rectify any omissions of acknowledgement in future if notified.
111279
6620.06
General Certificate of Education2011
Chemistry
Assessment Unit A2 3Internal Assessment
Practical Examination 1
[AC231]
TUESDAY 17 MAY, MORNING
MARKSCHEME
6620.06 2 [Turn over
AVAILABLEMARKS
Annotation1. Please do all marking in red ink.2. All scripts are checked for mathematical errors. Please adopt the system
of one tick () equals [1] mark e.g. if you have awarded 4 marks for part of a question then 4 ticks () should be on this candidate’s answer.
3. As candidates have access to scripts please do not write any inappropriate comments on their scripts.
1 (a) Rinse burette and pipette with appropriate solution [1] place 25.0 cm3 (or specified volume) in conical flask using a pipette filler [1]
add acid (20 cm3 of dilute sulfuric acid) [1] swirl flask during test [1]add permanganate solution quickly at first [1] then dropwise [1]do a rough titration [1]do 2(3) accurate titrations/until concordant/60.1 cm3
until end-point/colour change [1] maximum of [6]
(b) Titration Volume at
start/cm3Volume atend/cm3
Added volume/cm3
1
2
3
Average titre 5 cm3
Clearly labelled and neatly presented table, including units and the recording of the average titre. [1]
Significant figures: All accurate titration readings recorded to one decimal place (including initial burette reading a 0.0 if used). Accept, however, 0.00 and 0.05 but penalise by [–1] if other readings are given to two or more decimal places. The use of 0 is penalised by [–1] if used (only penalise once). [2]
Titration consistency: This is the difference between the accurate readings.
Difference Mark 60.1 2 60.2 1 .0.3 0 [2]
6620.06 3
AVAILABLEMARKS
Agreement with supervisor’s average titre(The supervisor’s titration value should be recorded in red ink beside the candidates’ average titre). If average titre calculated incorrectly the correct value should be determined and used for agreement mark.
Difference Mark 60.1 3 60.2 2 60.3 1 .0.3 0 [3]
Average titre: the inclusion of the rough titre in this calculation is penalised by [–1]. The average titre can be to two decimal places e.g. 21.33.
An incorrect calculation is 0 but this error must be carried through to other calculations, if appropriate. [2]
(c) colourless to pink [2]
(d) 5Fe21 1 8H1 1 MnO42 5Fe31 1 4H2O 1 Mn21 [2]
(e) Assuming a titration figure of 20.0 cm3 and a pipette figure of 25 cm3
volume 3 molarity of ammonium iron(II) sulfate 5 5 3 volume 3 molarity permanganate
25 3 M 5 5 3 20 3 0.02 5 2 25 3 M 5 0.08 [2]
(f) 0.08 mol 5 31.4 g 1 mol 5 31.4/0.08 5 392.5 g Fe(NH4)2(SO4)2nH2O 5 56 1 2 3 18 1 2 3 96 1 18n Fe(NH4)2(SO4)2nH2O 5 284 1 18n Hence 392.5 5 284 1 18n Hence 18n 5 108.5 Hence 18n 5 6.03 Hence 18n 5 6 [3] 25
6620.06 4 [Turn over
AVAILABLEMARKS
2 (a) Test Observation Deduction1 Describe the appearance of A.
pink/red/maroon crystals/solid [1]
transition metalcompound/cobaltion or compound/hydrated or water of crystallisation if crystals stated [1]
2 Add a spatula measure of A to approximately 50 cm3 of water and stir.
dissolves/soluble/disappears [1] pink [1] solution [1]Max. [2]
soluble/confirms transitionmetal compound/cobaltion or compound [1]award only once
3 Add 10 drops of silver nitrate solution to 2 cm3 of the solution of A in a test tube. Allow to stand.
white [1] precipitate [1] chloride [1]
4 Add 5 drops of sodium hydroxide solution to 2 cm3 of the solution of A in a test tube.
(dark) blue precipitate/darkens on standing [1]
insoluble hydroxide [1]Co(OH)2 etc
5 In a fume cupboard, add 6 cm3 of concentrated ammonia, slowly, to 2 cm3 of the solution of A in a test tube.
blue ppt [1](any) ppt dissolves [1]yellow solution [1]darkens/turns brown [1]Max. [3]
No deduction required
6 Add 4 cm3 of concentrated hydrochloric acid to 2 cm3 of the solution of A in a test tube.
goes blue [1]
No deduction required
A is (hydrated) cobalt chloride/cobalt(II) chloride [1]
6620.06 5
AVAILABLEMARKS
(b) Test Observation Deduction1 Describe the appearance of B.
white solid/crystals [1] high RMM/long chain/strong (intermolecular)forces named white organic solidno chromophoreglycine or alanine [1]
2 Heat one spatula measure of B in a test tube. Heat gently at first and then more strongly. Test any fumes with a glass rod dipped in concentrated hydrochloric acid.
White smoke
(smoke is) NH4Clmolecules contain N/ammonia [1]
3 (i) Dissolve 2 spatula measures of B in approximately 20 cm3 of water.
(ii) Use Universal Indicator paper to determine the pH of the solution of B.
green colour [1] pH 6/7 [1]
4 Add 6 drops of copper(II) sulfate solution, dropwise, to a test tube half-full of a solution of B.
blue colour [1] contains – NH2/– NH/glycine/any amino acid/correct comment on complex formed with amino acid [1]
5 To 3 cm3 of acidified potassium dichromate solution add one spatula measure of B and warm gently.
No change/stays orange [1]
not a primary or secondary alcohol/could be – COOH
– NH2– tert alcohol– ketone
dichromate not reduced [1]
Identity of B: glycine [1]
Maximum [25] 25
6620.06 6 [Turn over
AVAILABLEMARKS
3 (a) 2 Na(l) 1 O2(g) Na2O2(s) [2]
(b) Na2O2 5 2 3 23 1 2 3 16 5 46 1 32 5 78 1.3 g 5 1 3
78. 5 0.0167 mol 1
60( ) 46 g needed for 78 46 3 0.0167 5 0.768 5 0.77 g If an 80% yield will need error [–1] 100
80 3 0.77 g 5 0.96 g [4]
(c) sodium/Na2O2 reacts with water/moisture hence less sodium to react with oxygen yield of Na2O2 reduced/NaOH or H2O2/is formed [2]
(d)
oxygen or air
U tube
sodium
heat
air or oxygen
aluminium boat
e.g.anhydrous calcium chloride
[4]
(e) (i) Na2O2 1 H3PO4 Na2HPO4 1 H2O2 [2]
(ii) The (hydrated)/salt (of Na2HPO4.12H2O) [1] removes water from the solution [1] thus concentrating the solution [1]. [2]
(f) *retention time/peak [1] compare to pure sample of oxygen [1] – *depends on 1st line [2]
6620.06 7
AVAILABLEMARKS
Quality of written communication:
2 marks The candidate expresses ideas clearly and fluently through well-linked sentences and paragraphs. Arguments are generally relevant and well-structured. There are few errors of grammar, punctuation and spelling.
1 mark The candidate expresses ideas clearly, if not always fluently. Arguments may sometimes stray from the point. There may be some errors of grammar, punctuation and spelling, but not such as to suggest a weakness in these areas.
0 marks The candidate expresses ideas satisfactorily, but without precision. Arguments may be of doubtful relevance or obscurely presented. Errors in grammar, punctuation and spelling are sufficiently intrusive to disrupt the understanding of the passage. [2]
Total
20
70
TIME
2 hours 30 minutes.
INSTRUCTIONS TO CANDIDATES
Write your Centre Number and Candidate Number in the spaces provided at the top of this page.Answer all three questions.Write your answers in the spaces provided.
INFORMATION FOR CANDIDATES
The total mark for this paper is 70.Questions 1 and 2 are practical exercises each worth 25 marks.Question 3 is a planning exercise worth 20 marks.Quality of written communication will be assessed in Questions 3(d) and (e).You may not have access to notes, textbooks and other material
to assist you.A Periodic Table of elements (including some data) is provided.
051657
ADVANCEDGeneral Certificate of Education
2012
7563
For Examiner’s use only
Question Number Marks
Modera- tion Mark
1
2
3
TotalMarks
Chemistry
Assessment Unit A2 3Internal Assessment
Practical Examination 1
[AC231]
WEDNESDAY 9 MAY, MORNING
Centre Number
71
Candidate Number
AC231
TeacherMark
Examiner Check
Remark
7563 2
1 1.2 g of an impure sample of potassium iodate(V), KIO3, is to be analysed for percentage purity. A 250 cm3 solution of the sample was prepared in a volumetric flask.
(a) Describe how the 250 cm3 solution of potassium iodate(V) was prepared.
[6]
You are provided with:
a sample of the solution of potassium iodate(V) four 10 cm3 portions of dilute sulfuric acid four 1.0 g portions of potassium iodide 0.1 mol dm23 sodium thiosulfate solution starch indicator
Assuming that all the apparatus is clean and dry, you are required to carry out a titration to determine the percentage purity of the sample of potassium iodate(V) using the method given below.
● Pipette 25.0 cm3 of the potassium iodate(V) solution into a conical flask.
● Add 10 cm3 of dilute sulfuric acid to the conical flask. ● Add 1.0 g of potassium iodide to the conical flask and swirl the
flask to ensure it dissolves. ● Titrate, using the 0.1 mol dm23 sodium thiosulfate solution, until
the solution is straw coloured. ● Add starch indicator to the conical flask and titrate until the
indicator changes from blue-black to colourless.
TeacherMark
Examiner Check
Remark
7563 3 [Turn over
(b) Carry out the titration and record your results in a suitable table in the space below. Calculate the average titre.
[10]
7563 4
TeacherMark
Examiner Check
Remark (c) (i) Write the equation for the reaction between potassium
iodate(V) and potassium iodide in the presence of dilute sulfuric acid.
[2]
(ii) Write an ionic equation for this reaction.
[1]
(d) (i) Iodine reacts with sodium thiosulfate according to the equation:
I2 1 2S O2 322 S O4 6
22 1 2I2
Calculate the mass of KIO3 in the sample.
[5]
(ii) Calculate the percentage purity of the KIO3 sample.
[1]
7563 5 [Turn over
TeacherMark
Examiner Check
Remark2 Observation/deduction
Safety goggles must be worn at all times and care should be exercised during this investigation.
(a) You are provided with a sample of an inorganic compound labelled A.
(i) You are required to carry out the following tests on the compound and record your observations in the table.
Test Observations
1 Describe the appearance of A.[2]
2 Dissolve 3 spatula measures of A in 15 cm3 of deionised water.
Keep this solution for tests 3(a), 4, 5(a) and 6.
[1]
3 (a) Place 2 cm3 of the solution from test 2 in a test tube and add an equal volume of sodium hydroxide solution.
(b) Add a further 5 cm3 of sodium hydroxide solution to the test tube.
[3]
4 Place 2 cm3 of the solution from test 2 in a test tube and add 4 cm3 of edta solution.
[1]
5 (a) Place 2 cm3 of the solution from test 2 in a test tube and add 5 cm3 of dilute ammonia solution.
(b) Place 2 cm3 of the solution from test 5(a) in another test tube and add 2 cm3 of 1,2-diaminoethane (en) solution.
[2]
6 Place 2 cm3 of the solution from test 2 in another test tube and add 2 cm3 of barium chloride solution. Allow to stand.
[2]
7563 6
TeacherMark
Examiner Check
Remark (ii) Identify compound A.
[2]
(iii) Complex ions are formed in tests 4, 5(a) and 5(b). Suggest the formulae of the complex ions formed in these tests.
Test 4:
Test 5(a):
Test 5(b): [3]
(iv) Explain why a reaction occurs in test 5(b).
[2]
7563 7 [Turn over
TeacherMark
Examiner Check
Remark (b) You are provided with an aqueous mixture of two organic
compounds labelled Y. Both of the compounds in the mixture contain a carbonyl group.
(i) You are required to carry out the following tests on the organic mixture and record your observations in the table.
Test Observations
1 Describe the appearance of Y.Cautiously smell Y and give a description of its smell.
[2]
2 Place 3 cm3 of Y in a test tube and add 10 drops of acidified potassium dichromate solution. Warm in a water bath.
[2]
3 Place 3 cm3 of Y in another test tube and add half a spatula measure of sodium hydrogencarbonate.
[3]
(ii) State the two types of organic compounds in the mixture Y.
[2]
Maximum [25] marks
TeacherMark
Examiner Check
Remark
7563 8
3 Planning Exercise
Preparation and purification of the 2,4-dinitrophenylhydrazone derivative obtained from the reaction of methanal with 2,4-dinitrophenylhydrazine.
C�N�NH
NO2
NO2
H
H
The hydrazone, shown above, may be prepared by reacting excess aqueous 2,4-dinitrophenylhydrazine with methanal.
Methanal is gaseous at room temperature but can be obtained as a solution which contains 37% methanal, by mass.
(a) Write the equation for the formation of the 2,4-dinitrophenylhydrazone.
[2]
(b) Calculate the mass of methanal solution needed to form 1.4 g of the 2,4-dinitrophenylhydrazone assuming a 95% yield.
[4]
(c) Methanal causes severe irritation of the nasal system and affects the throat. What safety precaution needs to be carried out during the preparation?
[1]
TeacherMark
Examiner Check
Remark
7563 9 [Turn over
Quality of written communication is assessed in parts (d) and (e).
(d) The 2,4-dinitrophenylhydrazone is formed as an orange precipitate which is collected by suction filtration using a Buchner flask.
(i) Explain how “Buchner filtration” is carried out.
[3]
(ii) State why it is used in preference to normal filtration.
[2]
(e) The solvent used to recrystallise the 2,4-dinitrophenylhydrazone is ethanol.
(i) Explain why the 2,4-dinitrophenylhydrazone is soluble in ethanol and not in hexane.
[2]
(ii) Describe how you would recrystallise the 2,4-dinitrophenylhydrazone.
[4]
Quality of written communication [2]
THIS IS THE END OF THE QUESTION PAPER
112041
Permission to reproduce all copyright material has been applied for.In some cases, efforts to contact copyright holders may have been unsuccessful and CCEAwill be happy to rectify any omissions of acknowledgement in future if notified.
ADVANCED SUBSIDIARY (AS)General Certificate of Education
2012
ChemistryAssessment Unit A2 3
Internal AssessmentPractical Examination 1
[AC231]
WEDNESDAY 9 MAY, MORNING
7563.01
MARKSCHEME
7563.01 22 [Turn over
AVAILABLEMARKS
Annotation
1. Please do all marking in red ink.
2. All scripts should be checked for mathematical errors. Please adopt a system of one tick () equals 1 mark, e.g. if you have awarded 4 marks for part of a question then 4 ticks () should be on this candidate’s answer.
3. The total mark for each question should be recorded in a circle placed opposite the question number in the teacher mark column.
4. As candidates have access to scripts please do not write any inappropriate comments on their scripts.
General points
• All calculations are marked according to the number of errors made.
• Errors can be carried through. If the wrong calculation is carried out then the incorrect answer can be carried through. One mistake at the start of a question does not always mean that all marks are lost.
• Listing is when more than one answer is given for a question that only requires one answer, e.g. the precipitate from a chloride with silver nitrate is a white solid; if the candidate states a white or a cream solid, one answer is correct and one answer is wrong. Hence they cancel out.
• Although names might be in the mark scheme it is generally accepted that formulae can replace them. Formulae and names are often interchangeable in chemistry.
• The marking of colours is defined in the ‘CCEA GCE Chemistry Acceptable Colours’ document.
MARKING GUIDELINES
Interpretation of the Mark Scheme
• Carry error through This is where mistakes/wrong answers are penalised when made, but if carried
into further steps of the question, then no further penalty is applied. This pertains to calculations and observational/deduction exercises. Please annotate candidates’ answers by writing the letters c.e.t. on the appropriate place in the candidates’ answers.
• Oblique/forward slash This indicates an acceptable alternative answer(s).
• Brackets Where an answer is given in the mark scheme and is followed by a word/words in
brackets, this indicates that the information within the brackets is non-essential for awarding the mark(s).
7563.01 3 3
AVAILABLEMARKS
Section A
1 (a) Weigh 1.2 g of sample [1] Dissolve sample in (minimum) volume of deionised water with stirring [1] pour solution into (250 cm3) volumetric flask (through funnel) [1] indication of thorough rinsing of all apparatus (container, glass rod) [1] rinsings added to the volumetric flask [1] make up volume to 250 cm3 using deionised water until bottom of meniscus is on the line [1] invert/shake (to mix thoroughly) [1] To a maximum of [6] [6]
(b) Table [3] The Table should be drawn as a table. It should be labelled with the following:
initial (burette) reading, final (burette) reading and the titre. It is not necessary to use exactly these words but there should be appropriate columns and rows [1]. Units, i.e. cm3, should be stated [1].
The rough titration value should not be the same as the accurate values [1].
Use of decimal places [2] All burette readings should be to at least one decimal place – each mistake is
penalised by one mark.
(However initial burette readings of 0 are penalised once only.)
If used, the second decimal place position should be 0 or 5 only – other values will be penalised by 1 mark for each.
Average titre [2] Accurate titrations only should be used. The use of a rough value is [–1]. The average value can be calculated to two decimal places or more, e.g.
25.15 and 25.20 average to 25.175.
If three accurate titres are recorded, then the average titre must be calculated using all three accurate titres.
Any error is [–1]. This might be an incorrect calculation or the omission of units. If the average titre is included in the table then the units indicated on the table apply.
Titration consistency [1] This is the difference within the accurate titrations. If three accurate values
are given then the difference between highest and lowest is used.
Difference Mark ±0.1 [1] >0.1 [0]
Titration agreement [2] The correct average titre is used. If the incorrect average has been calculated
the correct one is calculated and used.
±0.1 [2] ±0.2 [1] >0.2 [0]
7563.01 44 [Turn over
AVAILABLEMARKS
The difference should be rounded to one decimal place. Please note that the supervisor’s titre should be recorded after the candidate’s table on their script in red ink.
The marks for table, decimal places etc. should be recorded at the candidate’s table of results. [10] (c) (i) KIO3 + 5KI + 3H2SO4 → 3I2 + 3K2SO4 + 3H2O unbalanced [–1] [2] (ii) IO3
– + 5I– + 6H+ → 3I2 + 3H2O [1]
(d) (i) moles of Na2S2O3 = 1000
average titre 0.1#
moles of I2 = moles of Na2S2O3
2
moles of KIO3 in 25.0 cm3 = moles of I2
3 moles of KIO3 in sample = moles of KIO3 in 25.0 cm3 × 10
mass of KIO3 in sample = moles of KIO3 in sample × RMM of KIO3 (214) [5]
(ii) percentage purity =
1.2mass of KIO3 100 [1] 25
error [–1] Alternative methods accepted
7563.01 5 5
AVAILABLEMARKS
2 (a) (i)
Test Observations
1 Describe the appearance of A. green [1] crystals/solid [1]accept blue-green/green-blue
2 Dissolve 3 spatula measures of A in 15cm3 of deionised water.
Keep this solution for tests 3(a), 4, 5(a) and 6.
green [1] (solution)(pale or dark green acceptable).
3 (a) Place 2cm3 of the solution from test 2 in a test tube and add an equal volume of sodium hydroxide solution.
(b) Add a further 5cm3 of sodium hydroxide solution to the test tube.
green [1] ppt [1] solid
does not dissolve [1]
4 Place 2cm3 of the solution from test 2 in another test tube and add 4cm3 of edta solution.
blue [1] solution(accept shades of blue)
5 (a) Place 2cm3 of the solution from test 2 in another test tube and add 5cm3 of dilute ammonia solution.
(b) Place 2cm3 of the solution from test 5(a) in another test tube and add 2cm3 of 1,2-diaminoethane (en) solution.
blue [1] solution
pink/purple/violet [1] solution
6 Place 2cm3 of the solution from test 2 in another test tube and add 2cm3 of barium chloride solution. Allow to stand.
white [1] ppt [1]
[11]
(ii) (hydrated) nickel [1] sulfate [1] or NiSO4 [2]
(iii) Test 4: [Ni(edta)]2– [1]
Test 5(a): [Ni(NH3)6]2+ [1]
Test 5(b): [Ni(en)3]2+ or [Ni(H2NCH2CH2NH2)3]2+ [1] [3] square brackets needed
(iv) more particles in solution/three en replace six NH3/bidentate replace monodentate [1] increase in disorder/entropy increases [1] [2]
7563.01 66 [Turn over
AVAILABLEMARKS
(b) (i)
Test Observations
1 Describe the appearance of Y. Cautiously smell Y and give a description of its smell.
colourless [1] descriptive, e.g. sharp [1] smell
2 Place 3 cm3 of Y in a test tube and add 10 drops of acidified potassium dichromate solution. Warm in a water bath.
orange [1] solutionchanges to green [1]
3 Place 3 cm3 of Y in another test tube and add half a spatula measure of sodium hydrogencarbonate.
fizzing/bubbles/effervescence [1]solid disappears [1]solution (remains) colourless [1]temperature change (down) [1]to maximum of [3]
[7]
(ii) aldehyde [1] (carboxylic) acid [1] [2]
maximum [25] 25
General:
Further observations
Candidates may record observations not recorded in the mark scheme, but credit should only be given to those observations recorded in the mark scheme.
Section A 50
7563.01 7 7
AVAILABLEMARKS
Section B
3 Planning Exercise
(a)
Molecular equation acceptable. [2]
(b) C OH
H is CH2O = 12 + 2 + 16 = 30
C NNH NO2
H
HNO2
= C7H6N4O4 = 210
210 g 2,4 DNP needs 30 g CH2O
1.4 g 210
1.4 30# = 0.2 g
37% is 0.2 g
[ need 37
100 0.2 g = 0.54 g
95% yield [ 95
100 0.54 g = 0.568 = 0.57 g [4]
(c) Fume cupboard [1]
(d) (i) place filter paper into Buchner funnel funnel placed into Buchner flask suck the air through/attached to pump [3]
(ii) Faster [1] dries crystals [1] [2]
(e) (i) Recognise that hydrazone and ethanol are both polar/hydrazone can form H-bonds with ethanol [1] Hexane is non-polar/cannot form H-bonds with hydrazone [1] [2]
(ii) Minimum volume [1] hot ethanol [1] filter [1] allow (to cool) and form crystals [1] [4] Quality of written communication [2]
C O + NH2NH C NNH NO2+ H2ONO2
H H
H HNO2
NO2
7563.01 88 [Turn over
AVAILABLEMARKS
Quality of written communication
2 marks The candidate expresses ideas clearly and fluently through well-linked sentences and paragraphs. Arguments are generally relevant and well-structured. There are few errors of grammar, punctuation and spelling.
1 mark The candidate expresses ideas clearly, if not always fluently. Arguments may sometimes stray from the point. There may be some errors of grammar, punctuation and spelling, but not such as to suggest a weakness in these areas.
0 marks The candidate expresses ideas satisfactorily, but without precision. Arguments may be of doubtful relevance or obscurely presented. Errors in grammar, punctuation and spelling are sufficiently intrusive to disrupt the understanding of the passage. 20
Section B 20
Total 70
TIME
2 hours 30 minutes.
INSTRUCTIONS TO CANDIDATES
Write your Centre Number and Candidate Number in the spaces provided at the top of this page.Answer all three questions.Write your answers in the spaces provided.
INFORMATION FOR CANDIDATES
The total mark for this paper is 70.Questions 1 and 2 are practical exercises each worth 25 marks.Question 3 is a planning exercise worth 20 marks.Quality of written communication will be assessed in Questions 3(d) and (e).You may not have access to notes, textbooks and other material
to assist you.A Periodic Table of elements (including some data) is provided.
051658
ADVANCEDGeneral Certificate of Education
2012
7564
For Examiner’s use only
Question Number Marks
Modera- tion Mark
1
2
3
TotalMarks
Chemistry
Assessment Unit A2 3Internal Assessment
Practical Examination 2
[AC232]
THURSDAY 10 MAY, MORNING
Centre Number
71
Candidate Number
AC232
7564 2
TeacherMark
Examiner Check
Remark1 1.2 g of an impure sample of potassium iodate(V), KIO3, is to be
analysed for percentage purity. A 250 cm3 solution of the sample was prepared in a volumetric flask.
(a) Describe how the 250 cm3 solution of potassium iodate(V) was prepared.
[6]
You are provided with:
a sample of the solution of potassium iodate(V) four 10 cm3 portions of dilute sulfuric acid four 1.0 g portions of potassium iodide 0.1 mol dm23 sodium thiosulfate solution starch indicator
Assuming that all the apparatus is clean and dry, you are required to carry out a titration to determine the percentage purity of the sample of potassium iodate(V) using the method given below.
● Pipette 25.0 cm3 of the potassium iodate(V) solution into a conical flask.
● Add 10 cm3 of dilute sulfuric acid to the conical flask. ● Add 1.0 g of potassium iodide to the conical flask and swirl the
flask to ensure it dissolves. ● Titrate, using the 0.1 mol dm23 sodium thiosulfate solution, until
the solution is straw coloured. ● Add starch indicator to the conical flask and titrate until the
indicator changes from blue-black to colourless.
7564 3 [Turn over
TeacherMark
Examiner Check
Remark (b) Carry out the titration and record your results in a suitable table
in the space below. Calculate the average titre.
[10]
7564 4
TeacherMark
Examiner Check
Remark (c) (i) Write the equation for the reaction between potassium
iodate(V) and potassium iodide in the presence of dilute sulfuric acid.
[2]
(ii) Write an ionic equation for this reaction.
[1]
(d) (i) Iodine reacts with sodium thiosulfate according to the equation:
I2 1 2S O2 322 S O4 6
22 1 2I2
Calculate the mass of KIO3 in the sample.
[5]
(ii) Calculate the percentage purity of the KIO3 sample.
[1]
7564 5 [Turn over
TeacherMark
Examiner Check
Remark2 Observation/deduction
Safety goggles must be worn at all times and care should be exercised during this investigation.
(a) You are provided with a sample of an inorganic compound labelled B.
(i) You are required to carry out the following tests on the compound and record your observations in the table.
Test Observations
1 Describe the appearance of B.
[2]
2 Dissolve 3 spatula measures of B in 15 cm3 of deionised water.
Keep this solution for tests 3(a), 4(a), 5(a) and 6.
[1]
3 (a) Place 3 cm3 of the solution from test 2 in a test tube and add 5 drops of sodium hydroxide solution.
(b) Add a further 5 cm3 of sodium hydroxide solution to the test tube.
[3]
4 (a) In a fume cupboard place 2 cm3 of the solution from test 2 in a test tube and add 3 drops of concentrated ammonia solution.
(b) Add a further 5 cm3 of concentrated ammonia solution to the test tube.
[2]
5 (a) Place 3 cm3 of the solution from test 2 in a test tube and in a fume cupboard, add 5 cm3 of concentrated hydrochloric acid.
(b) Place 3 cm3 of the solution from test 5(a) in another test tube and add 5 cm3 of edta solution.
[2]
6 Place 3 cm3 of the solution from test 2 in another test tube and add 3 cm3 of barium chloride solution.
[2]
7564 6
TeacherMark
Examiner Check
Remark (ii) Identify compound B.
[2]
(iii) Complex ions are formed in tests 4(b), 5(a) and 5(b). Write the formulae of the complex ions formed in these tests.
Test 4(b):
Test 5(a):
Test 5(b): [3]
(iv) Explain why a reaction occurs in test 5(b).
[2]
7564 7 [Turn over
(b) You are provided with an aqueous mixture of two organic compounds labelled Z. Both of the compounds in the mixture contain a carbonyl group.
(i) You are required to carry out the following tests on the organic mixture and record your observations in the table.
Test Observations
1 Describe the appearance of Z.Cautiously smell Z and give a description of its smell.
[2]
2 Place 3 cm3 of Z in a test tube and add 10 drops of acidified potassium dichromate solution. Warm in a water bath.
[1]
3 Place 3 cm3 of Z in another test tube and add half a spatula measure of sodium hydrogencarbonate.
[3]
(ii) State the two types of organic compounds in the mixture Z.
[2]
Maximum [25] marks
TeacherMark
Examiner Check
Remark
7564 8
TeacherMark
Examiner Check
Remark3 Planning Exercise
Preparation and purification of the 2,4-dinitrophenylhydrazone derivative obtained from the reaction of butanone with 2,4-dinitrophenylhydrazine.
C�N�NH
NO2
NO2
C2H
5
CH3
The hydrazone may be prepared by reacting excess aqueous 2,4-dinitrophenylhydrazine with butanone.
Butanone is a liquid at room temperature with a density of 0.80 g cm23.
(a) Write the equation for the formation of the 2,4-dinitrophenylhydrazone.
[2]
(b) Calculate the volume of butanone needed to form 5.4 g of the 2,4-dinitrophenylhydrazone assuming a 90% yield.
[4]
(c) Butanone causes irritation of the eyes and nose. What safety precaution needs to be carried out during the preparation?
[1]
7564 9 [Turn over
TeacherMark
Examiner Check
RemarkQuality of written communication is assessed in parts (d) and (e).
(d) The 2,4-dinitrophenylhydrazone is formed as an orange precipitate which is collected by suction filtration using a Buchner flask.
(i) Explain how “Buchner filtration” is carried out.
[3]
(ii) State why it is used in preference to normal filtration.
[2]
(e) The solvent used to recrystallise the 2,4-dinitrophenylhydrazone is methanol.
(i) Explain why the 2,4-dinitrophenylhydrazone is soluble in methanol and not in octane.
[2]
(ii) Describe how you would recrystallise the 2,4-dinitrophenylhydrazone.
[4]
Quality of written communication [2]
THIS IS THE END OF THE QUESTION PAPER
112043
Permission to reproduce all copyright material has been applied for.In some cases, efforts to contact copyright holders may have been unsuccessful and CCEAwill be happy to rectify any omissions of acknowledgement in future if notified.
ADVANCEDGeneral Certificate of Education
2012
MARKSCHEME
Standardising Meeting Version
Chemistry
Assessment Unit A2 3
Internal AssessmentPractical Examination 2
[AC232]
THURSDAY 10 MAY, MORNING
7564.01
2
AVAILABLE MARKS
7564.01
Annotation
1. Please do all marking in red ink.
2. All scripts should be checked for mathematical errors. Please adopt a system of one tick () equals 1 mark, e.g. if you have awarded 4 marks for part of a question then 4 ticks () should be on this candidate’s answer.
3. The total mark for each question should be recorded in a circle placed opposite the question number in the teacher mark column.
4. As candidates have access to scripts please do not write any inappropriate comments on their scripts.
General points
• All calculations are marked according to the number of errors made.
• Errors can be carried through. If the wrong calculation is carried out then the incorrect answer can be carried through. One mistake at the start of a question does not always mean that all marks are lost.
• Listing is when more than one answer is given for a question that only requires one answer, e.g. the precipitate from a chloride with silver nitrate is a white solid; if the candidate states a white or a cream solid, one answer is correct and one answer is wrong. Hence they cancel out.
• Although names might be in the mark scheme it is generally accepted that formulae can replace them. Formulae and names are often interchangeable in chemistry.
• The marking of colours is defined in the ‘CCEA GCE Chemistry Acceptable Colours’ document.
MARKING GUIDELINES
Interpretation of the Mark Scheme
• Carry error through This is where mistakes/wrong answers are penalised when made, but if carried into further steps of the question, then no further penalty is applied. This pertains to calculations and observational/deduction exercises. Please annotate candidates’ answers by writing the letters c.e.t. on the appropriate place in the candidates’ answers.
• Oblique/forward slash This indicates an acceptable alternative answer(s).
• Brackets Where an answer is given in the mark scheme and is followed by a word/words in brackets, this indicates that the information within the brackets is non-essential for awarding the mark(s).
37564.01
AVAILABLE MARKS
Section A
1 (a) Weigh 1.2 g of sample [1] Dissolve sample in (minimum) volume of deionised water with stirring [1] pour solution into (250 cm3) volumetric flask (through funnel) [1] indication of thorough rinsing of apparatus (container, glass rod) [1] rinsings added to the volumetric flask [1] make up volume to 250 cm3 using deionised water until bottom of meniscus is on the line [1] invert/shake (to mix thoroughly) [1] To a maximum of [6] [6]
(b) Table [3] The Table should be drawn as a table. It should be labelled with the following: initial (burette) reading, final (burette) reading and the titre. It is not necessary to use exactly these words but there should be appropriate columns and rows [1]. Units, i.e. cm3, should be stated [1].
The rough titration value should not be the same as the accurate values [1].
Use of decimal places [2] All burette readings should be to at least one decimal place – each mistake is penalised by one mark.
(However initial burette readings of 0 are penalised once only.)
If used, the second decimal place position should be 0 or 5 only – other values will be penalised by 1 mark for each.
Average titre [2] Accurate titrations only should be used. The use of a rough value is [–1]. The average value can be calculated to two decimal places or more, e.g. 25.15 and 25.20 average to 25.175.
If three accurate titres are recorded, then the average titre must be calculated using all three accurate titres.
Any error is [–1]. This might be an incorrect calculation or the omission of units. If the average titre is included in the table then the units indicated on the table apply.
Titration consistency [1] This is the difference within the accurate titrations. If three accurate values are given then the difference between highest and lowest is used.
Difference Mark ±0.1 [1] >0.1 [0]
Titration agreement [2] The correct average titre is used. If the incorrect average has been calculated the correct one is calculated and used.
±0.1 [2] ±0.2 [1] >0.2 [0]
4
AVAILABLE MARKS
7564.01
The difference should be rounded to one decimal place. Please note that the supervisor’s titre should be recorded after the candidate’s table on their script in red ink.
The marks for table, decimal places etc. should be recorded at the candidate’s table of results. (c) (i) KIO3 + 5KI + 3H2SO4 → 3I2 + 3K2SO4 + 3H2O unbalanced [–1] [2] (ii) IO3 + 5I– + 6H+ → 3I2 + 3H2O [1]
(d) (i) moles of Na2S2O3 = average titre 0.1
1000 moles of I2 =
moles of Na2S2O32
moles of KIO3 in 25.0 cm3 = moles of I2
3 moles of KIO3 in sample = moles of KIO3 in 25.0 cm3 × 10
mass of KIO3 in sample = moles of KIO3 in sample × RMM of KIO3 (214) [5]
(ii) percentage purity = mass of KIO31.2 100 [1]
error [–1] Alternative methods accepted 25
57564.01
AVAILABLE MARKS
2 (a) You are provided with a sample of an inorganic compound labelled B.
(i) You are required to carry out the following tests on the compound and record your observations in the table.
Test Observations
1 Describe the appearance of B. brown/red/pink [1]solid/crystals [1]
[2]
2 Dissolve 3 spatula measures of B in 15 cm3 of deionised water.
Keep this solution for tests 3(a), 4(a), 5(a) and 6.
red/pink [1] solution
[1]
3 (a) Place 3 cm3 of the solution from test 2 in a test tube and add 5 drops of sodium hydroxide solution.
(b) Add a further 5 cm3 of sodium hydroxide solution to the test tube.
blue [1] ppt [1] solid
does not dissolve [1][3]
4 (a) In a fume cupboard place 2 cm3 of the solution from test 2 in a test tube and add 3 drops of concentrated ammonia solution.
(b) Add a further 5 cm3 of concentrated ammonia solution to the test tube.
(blue) ppt [1]
brown/yellow solution [1](accept shades) [2]
5 (a) Place 3 cm3 of the solution from test 2 in a test tube and add 5 cm3 of concentrated hydrochloric acid.
(b) Place 3 cm3 of the solution from test 5(a) in another test tube and add 5 cm3 of edta solution.
blue solution [1]accept purple/violetsolution
pink [1] solution
[2]
6 Place 3 cm3 of the solution from test 2 in another test tube and add 3 cm3 of barium chloride solution.
white [1] ppt [1]
[2] [12] (ii) (hydrated) cobalt [1] sulfate [1] or CoSO4 [2]
(iii) Test 4(b): [Co(NH3)6]2+ Test 5(a): [CoCl4]2– Test 5(b): [Co(edta)]2– [3] square brackets needed
(iv) more particles in solution/one edta replaces four Cl–/hexadentate replaces monodentate [1]
increase in disorder/entropy increases [1] [2]
6
AVAILABLE MARKS
7564.01
`(b) (i)
Test Observations
1 Describe the appearance of Z. Cautiously smell Z and give a description of its smell.
colourless [1] solution descriptive, e.g. sharp [1] smell
[2]
2 Place 3 cm3 of Z in a test tube and add 10 drops of acidified potassium dichromate solution. Warm in a water bath.
remains orange [1]
[1]
3 Place 3 cm3 of Z in another test tube and add half a spatula measure of sodium hydrogencarbonate.
fizzing/bubbles/effervescence [1]solid disappears [1]solution (remains) colourless [1]temperature change (down) [1]to maximum of [3]
[3] [6]
(ii) ketone [1]/ester/amide (carboxylic) acid [1] [2]
Maximum [25] 25
General:
Further observations
Candidates may record observations not recorded in the mark scheme, but credit should only be given to those observations recorded in the mark scheme.
Section A 50
77564.01
AVAILABLE MARKS
Section B
3 Planning Exercise
(a)
Molecular equation acceptable [2]
(b) C O C2H5
CH3
is C4H8O = 48 + 8 + 16 = 72
252 g 2,4 DNP needs 72 g butanone
5.4 g 5.4 × 72252
= 1.54 g
d = m/v 0.80 = 1.54/v
v = 1.54/0.80 = 1.93 cm3 [4]
further step for 90% yield – 2.14 cm3
(c) Fume cupboard [1]
(d) (i) funnel placed into Buchner flask place filter paper into Buchner funnel suck the air through/attached to pump maximum [3]
(ii) Faster [1] drier [1] [2]
(e) (i) Recognise that hydrazone and methanol are both polar/hydrazone can form H-bonds with methanol [1] octane is non-polar/cannot form H-bonds with hydrazone [1] [2]
(ii) Minimum volume [1] hot methanol [1] filter [1] allow (to cool) and form crystals [1] [4]
Quality of written communication [2]
C NNH NO2
C2H5
CH3
NO2
= C10H12N4O4 = 120 + 12 + 56 + 64 = 252
C O + NH2NH C NNH NO2 NO2
C2H5C2H5
CH3CH3
NO2 NO2
+ H2O
8
AVAILABLE MARKS
7564.01
Quality of written communication
2 marks The candidate expresses ideas clearly and fluently through well-linked sentences and paragraphs. Arguments are generally relevant and well-structured. There are few errors of grammar, punctuation and spelling.
1 mark The candidate expresses ideas clearly, if not always fluently. Arguments may sometimes stray from the point. There may be some errors of grammar, punctuation and spelling, but not such as to suggest a weakness in these areas.
0 marks The candidate expresses ideas satisfactorily, but without precision. Arguments may be of doubtful relevance or obscurely presented. Errors in grammar, punctuation and spelling are sufficiently intrusive to disrupt the understanding of the passage. 20
Section B 20
Total 70
TIME
2 hours 30 minutes.
INSTRUCTIONS TO CANDIDATES
Write your Centre Number and Candidate Number in the spaces provided at the top of this page.Answer all three questions.Write your answers in the spaces provided.
INFORMATION FOR CANDIDATES
The total mark for this paper is 70.Questions 1 and 2 are practical exercises each worth 25 marks.Question 3 is a planning exercise worth 20 marks.Quality of written communication will be assessed in Questions 3(d) and (e).You may not have access to notes, textbooks and other material
to assist you.A Periodic Table of the Elements, containing some data, is included in this question paper.
061274
ADVANCEDGeneral Certificate of Education
2013
8190
For Examiner’s use only
Question Number Marks
Modera- tion Mark
1
2
3
TotalMarks
Chemistry
Assessment Unit A2 3Internal Assessment
Practical Examination 1
[AC231]
WEDNESDAY 15 MAY, MORNING
Centre Number
71
Candidate Number
AC231
8190 2
TeacherMark
Examiner Check
Remark1 Titration exercise
Hardness in water may be caused by the presence of dissolved calcium ions.
You are provided with:
A solution of edta of concentration 0.01 mol dm23
A sample of hard water Four portions of pH10 buffer solution Eriochrome Black T indicator solution (use four drops) A sample solution showing the colour at the end point
Assuming that all apparatus is clean and dry, you are required to carry out a titration and use your results to determine the concentration of calcium ions in the hard water sample.
(a) Give details of the procedure you intend to use. The edta solution should go into the burette.
[6]
TeacherMark
Examiner Check
Remark
8190 3 [Turn over
(b) Carry out your procedure. Present your results in a suitable table and calculate the average titre.
[8]
(c) State the colour change at the end point of the titration.
From to [2]
TeacherMark
Examiner Check
Remark
8190 4
(d) With reference to the following equation explain the reason for adding the pH10 buffer to the reaction mixture.
Ca21 1 H2(edta)22 [Ca(edta)]22 1 2H1
[2]
(e) Calculate the concentration of the calcium ions in the hard water in mg dm23.
[5]
(f) Name another test that would be used to confirm the presence of calcium ions in the hard water, stating the expected result.
[2]
TeacherMark
Examiner Check
Remark
8190 5 [Turn over
2 Observation/deduction
Safety glasses must be worn at all times and care should be exercised during this practical examination.
(a) You are provided with a salt, labelled X. Carry out the following tests. Record your observations and deductions in the spaces below.
Test Observations Deductions
1 Describe the appearance of X.
[1] [1]
2 Add a spatula measure of X to 50 cm3 of deionised water and stir until there is no further change.
[1] [1]
3 Add 5 drops of silver nitrate solution to a test tube containing 2 cm3 of the solution of X. Allow the mixture to stand.
[3] [1]
4 Put 2 cm3 of the solution of X into a test tube.
(a) Add 5 drops of sodium hydroxide solution.
(b) Add a further 5 cm3 of sodium hydroxide solution.
[3] [3]
5 Place a spatula measure of solid X in a dry boiling tube and heat gently.
[2] [1]
Give the name of compound X
[2]
TeacherMark
Examiner Check
Remark
8190 6
(b) You are provided with an organic liquid containing one functional group, labelled Y. Carry out the following tests and record your observations and deductions in the spaces below. The mass spectrum of Y is also provided.
Test Observations Deductions
1 Place 2 cm3 of Y into a boiling tube. Place in a test tube rack.
(a) Under supervision, cautiously add a very small measure of phosphorus(V) chloride in a fume cupboard.
(b) In a fume cupboard, hold the stopper of a bottle of concentrated ammonia solution over the boiling tube used in test 1(a).
[2]
[1]
[1]
[1]
2 Place 2 cm3 of Y into a test tube. Add 1 cm3 of sodium carbonate solution.
[1] [1]
(i) What homologous series does Y belong to?
[1]
TeacherMark
Examiner Check
Remark
8190 7 [Turn over
Use the following mass spectrum to deduce the structure of Y.
10 15 20 25 30 35 40 45 50 55 60 65 70 75
100
80
60
40
20
0
m/z
rela
tive
abun
danc
e
(ii) Draw the structure of Y below.
[1]
Maximum [25] marks
TeacherMark
Examiner Check
Remark
8190 8
3 Planning exercise
Preparation of urea
Urea, (NH2)2CO, was first synthesised by Friedrich Wöhler in 1828. Today some seven million tons of urea are produced per year mainly for use as a fertiliser.
Urea can be prepared in the laboratory by reacting lead(II) cyanate, Pb(CNO)2, with ammonia and water to produce lead(II) hydroxide and ammonium cyanate, NH4CNO. The ammonium cyanate then rearranges when heated to form urea, which has a melting point of 133 °C.
O
C
H2N NH2
urea
(a) Write an equation for the reaction of lead(II) cyanate with ammonia and water.
[2]
(b) Assuming a 70% yield, calculate the mass of lead(II) cyanate required to produce 450 g of ammonium cyanate.
[4]
TeacherMark
Examiner Check
Remark
8190 9 [Turn over
(c) The ammonium cyanate rearranges to form urea as shown in the equation below.
NH4CNO (NH2)2CO
(i) The crude product is purified by dissolving in the minimum volume of hot ethanol, filtering to remove insoluble impurities, and cooling. What name is given to this purification process?
[1]
(ii) What practical considerations determine the choice of solvent used?
[2]
(iii) Why is the minimum amount of hot ethanol used?
[1]
(iv) How is the pure dry product obtained from the filtrate?
[2]
Quality of written communication will be assessed in parts (d) and (e).
(d) Giving practical details, describe how you would determine whether or not the crystals of urea produced are pure.
[3]
TeacherMark
Examiner Check
Remark
8190 10
(e) How could you use the following infrared spectroscopic data to follow the progress of the rearrangement of ammonium cyanate to urea?
Bond Wave number/cm21
C O 1650
C N 2100
N–H (in amines) 3200–3500
[3]
Quality of written communication [2]
THIS IS THE END OF THE QUESTION PAPER
113041
Permission to reproduce all copyright material has been applied for.In some cases, efforts to contact copyright holders may have been unsuccessful and CCEAwill be happy to rectify any omissions of acknowledgement in future if notified.
ADVANCEDGeneral Certificate of Education
2013
8190.01 F
MARKSCHEME
ChemistryAssessment Unit A2 3
Internal AssessmentPractical Examination 1
[AC231]
WEDNESDAY 15 MAY, MORNING
8190.01 F 22 [Turn over
AVAILABLEMARKS
Annotation
1. Please do all marking in red ink.
2. All scripts should be checked for mathematical errors. Please adopt a system of one tick () equals 1 mark, e.g. if you have awarded 4 marks for part of a question then 4 ticks () should be on this candidate’s answer.
3. The total mark for each question should be recorded in a circle placed opposite the question number in the teacher mark column.
4. As candidates have access to scripts please do not write any inappropriate comments on their scripts.
General points
• All calculations are marked according to the number of errors made.
• Errors can be carried through. If the wrong calculation is carried out then the incorrect answer can be carried through. One mistake at the start of a question does not always mean that all marks are lost.
• Any number of decimal places may be used provided the ‘rounding’ is correct.
• Listing is when more than one answer is given for a question that only requires one answer, e.g. the precipitate from a chloride with silver nitrate is a white solid; if the candidate states a white or a cream solid, one answer is correct and one answer is wrong. Hence they cancel out.
• Although names might be in the mark scheme it is generally accepted that formulae can replace them. Formulae and names are often interchangeable in chemistry.
• The marking of colours is defined in the ‘CCEA GCE Chemistry Acceptable Colours’ document.
MARKING GUIDELINES
Interpretation of the Mark Scheme
• Carry error through This is where mistakes/wrong answers are penalised when made, but if carried
into further steps of the question, then no further penalty is applied. This pertains to calculations and observational/deduction exercises. Please annotate candidates’ answers by writing the letters c.e.t. on the appropriate place in the candidates’ answers.
• Oblique/forward slash This indicates an acceptable alternative answer(s).
• Brackets Where an answer is given in the mark scheme and is followed by a word/words in
brackets, this indicates that the information within the brackets is non-essential for awarding the mark(s).
8190.01 F 3 3
AVAILABLEMARKS
1 Titration exercise
(a) Rinse out a pipette with the hard water and transfer 25.0 cm3 of the hard water into a (conical) flask [1] Add a portion of pH10 buffer solution [1] Add 4 drops of Eriochrome Black T to the conical flask and swirl [1] Rinse out the burette with the edta solution and fill the burette [1] Titrate with/add the edta solution from the burette until colour matches reference sample [1] Rough and two/three accurate titrations [1] [6]
(b) Table [3] The Table should be drawn as a table. It should be labelled with the following:
initial burette reading, final burette reading and the titre. It is not necessary to use exactly these words but there should be appropriate columns and rows.
The recorded readings should be checked for mathematical accuracy [1]. The rough titration value should be greater than the accurate values (no more
than 2 cm3) [1]. Units, i.e. cm3, should be stated [1]. Use of decimal places [2] All burette readings should be to at least one decimal place – each mistake is
penalised by one mark. (However initial burette readings of 0 are penalised once only.)
If used, the second decimal place position should be 0 or 5 only – other values will be penalised by 1 mark for each.
Average titre [2] Accurate titrations only should be used. The use of a rough value is [–1]. The average value can be calculated to two decimal places or more, e.g. 25.15 and 25.20 average to 25.175. If three accurate titres are recorded, then the average titre must be calculated
using all three accurate titres.
Any error is [–1]. This might be an incorrect calculation or the omission of units. If the average titre is included in the table then the units indicated on the table apply.
Titration consistency [1] This is the difference within the accurate titrations. If three accurate values are
given then the difference between highest and lowest is used.
Difference Mark ±0.1 [1] >0.1 [0]
(c) red [1] to blue [1] [2]
(d) to remove H+ [1] and prevent reverse of equilibrium [1] [2]
8190.01 F 44 [Turn over
AVAILABLEMARKS
(e) assuming an average titre of 22.8 cm3 moles edta = (22.8 × 0.01)/1000 = 2.28 × 10–4
moles Ca2+ = 2.28 × 10–4
concentration of Ca2+ = (2.28 × 10–4 × 1000)/25 = 9.12 × 10–3 mol dm–3
mass Ca2+ = 9.12 × 10–3 × 40 = 0.3648 g concentration of Ca2+ = 364.8 (mg dm–3) [–1] each error [5]
Consequential marking/carry error through (cet) to be applied in calculations. (f) flame test [1] brick red colour [1] [2] 25
8190.01 F 5 5
AVAILABLEMARKS
2 Observation/deduction
There are 28 scoring points available in Question 2. However the maximum mark for this question is 25.
Please see additional notes at the end of Question 2.
If the candidate scores more than 25 then MAX 25 should be written at beginning of question in the teacher mark column.
(a)
Test Observation Deduction
1 Describe the appearance of X.
green solid [1] Transition metal compound or ion [1]
2 Add a spatula measure of X to 50 cm3 of deionised water and stir until there is no further change. green solution [1]
Cr 3+/Fe2+/Ni2+ [1]
3 Add 5 drops of silver nitrate solution to a test tube containing 2 cm3 of the solution of X. Allow the matrix to stand.
white [1] ppt [1]in green solution [1] chloride ion present [1]
4 Put 2 cm3 of the solution of X into a test tube.
(a) Add 5 drops of sodium hydroxide solution.
(b) Add a further 5 cm3 of sodium hydroxide solution.
green-blue [1] ppt [1]
ppt dissolves/(green) solution [1]
insoluble hydroxide [1]
Cr 3+/Cr(OH)3 / Cr(OH)3 (H2O)3 [1]
amphoteric [1]
5 Place a spatula measure of solid X in a dry boiling tube and heat gently.
colourless liquidon sides of tube [1]
crystals change colour [1]
hydrated/water of crystallisation present [1]
Give the name of compound X. hydrated [1] chromium(lll) chloride [1] [2]
8190.01 F 66 [Turn over
AVAILABLEMARKS
(b)
Test Observation Deduction
1 Place 2 cm3 of Y into a boiling tube. Place in a test
tube rack.
(a) Under supervision, cautiously add a very small measure of phosphorus (V) chloride in a fume cupboard.
(b) In a fume cupboard, hold the stopper of a bottle of concentrated ammonia solution over the test tube used in test (a).
steamy fumes [1]effervescence [1]
white smoke [1]
–OH group present [1]
HCI [1]
2 Place 2 cm3 of Y into a test tube. Add 1 cm3 of sodium carbonate solution. fizz/effervescence [1] Y is acidic [1]
(i) What homologous series does Y belong to? carboxylic acids [1]
(ii) Structure of Y O
OH
C C
H
H
H C
H
H
[1] Max 25
8190.01 F 7 7
AVAILABLEMARKS
General:
An incorrect deduction can be carried through to naming the salt. A deduction based on an incorrect observation can be credited on the basis of cet.
Wrong placing of answers
In the observation/deduction question candidates may write their answers in the wrong column. This is not the penalised, e.g. a deduction written in the observation column may be credited, if correct.
Further observations
Candidates may record observations not recorded in the mark scheme, but credit should only be given to those observations recorded in the mark scheme.
Question 2 (a)
Test 1 Crystals is acceptable but not powder. Dark green is acceptable. “Transition metal ion/compound” is OK. “Transition metal” is wrong. At this point the word ‘possibly’ or similar should be used if stating possible ions. At least two out of Cr3+, Fe2+, Ni2+ must be mentioned. Ions must either be given their correct symbol and charge or be referred to as an ion (e.g. “Cr3+” or “chromium ions” are acceptable; “Cr” or “chromium” are not acceptable).
Test 2 Again at least two ions should be mentioned. Candidates can score here for the same deduction made in Test 1. No mark is awarded for deducing that X is soluble as it is referred to as a “solution” in later tests.
Test 3 When allowed to stand a white precipitate will settle at the bottom of the test tube. No other colour is acceptable. “Chloride” or “chloride ion” or “CI–” are acceptable. “Chlorine” or “CI” are not acceptable.
Test 4(a) The list of acceptable colours states that the precipitate formed, Cr(OH)3,is green-blue. However the precipitate could legitimately be observed as being pale blue, or grey-blue and these are also acceptable.
Test 5 The most important observation is the formation of the colourless liquid on the walls of the boiling tube indicating the presence of water of crystallisation, but since the crystals do change colour then this is also accepted. The actual colour is not important. If the only observation is the colour change of the crystals the candidate cannot score a mark for deduction.
Name of X The oxidation state (III) is not necessary but if an incorrect oxidation state is given then a mark is lost.
Question 2 (b)
Test 1(b) The observation could also be described as white fumes.
8190.01 F 88 [Turn over
AVAILABLEMARKS
3 Planning Exercise
(a) Pb(CNO)2 + 2NH3 + 2H2O → Pb(OH)2 + 2NH4CNO [2] (b) moles NH4CNO = 450/60 = 7.5 70% →100% (7.5/70) × 100 = 10.7 (1:2) moles Pb(CNO)2 = 10.7/2 = 5.35 mass Pb(CNO)2 = 5.35 × 291 = 1557 g [4]
(c) (i) recrystallisation [1] (ii) desired product soluble in hot solvent [1] but insoluble when solvent is
cold [1]/other impurities remain in solution when cold [1] [2]
(iii) prevents loss of product [1]
(iv) filter [1] dry in low temperature oven/desiccator [1] [2]
(d) sample in capillary tube sealed at one end [1] heat slowly [1] (in oil bath) sharp melting point at 133 °C indicates purity [1] [3]
(e) peak at 2100 cm–1 diminished [1] peaks form at 1650 cm–1 [1] and 3200–3500 cm–1 [1] [3] Quality of written communication marked in Questions 3 (d) and (e) [2] 20
Total 70
TIME
2 hours 30 minutes.
INSTRUCTIONS TO CANDIDATES
Write your Centre Number and Candidate Number in the spaces provided at the top of this page.Answer all three questions.Write your answers in the spaces provided.
INFORMATION FOR CANDIDATES
The total mark for this paper is 70.Questions 1 and 2 are practical exercises each worth 25 marks.Question 3 is a planning exercise worth 20 marks.Quality of written communication will be assessed in Question 3(f).You may not have access to notes, textbooks and other materialto assist you.
A Periodic Table of the Elements, containing some data, is included in this question paper.
061275
ADVANCEDGeneral Certificate of Education
2013
8191
For Examiner’s use only
Question Number Marks
Modera- tion Mark
1
2
3
TotalMarks
Chemistry
Assessment Unit A2 3Internal Assessment
Practical Examination 2
[AC232]
THURSDAY 16 MAY, MORNING
Centre Number
71
Candidate Number
AC232
8191 2
TeacherMark
Examiner Check
Remark1 Titration exercise
Hardness in water may be caused by the presence of dissolved magnesium ions.
You are provided with:
A solution of edta of concentration 0.02 mol dm23
A sample of hard water Four portions of pH 10 buffer solution Eriochrome Black T indicator solution (use four drops) A sample solution showing the colour at the end point
Assuming that all apparatus is clean and dry, you are required to carry out a titration and use your results to determine the concentration of magnesium ions in the hard water sample.
(a) Give details of the procedure you intend to use. The edta solution should go into the burette.
[6]
TeacherMark
Examiner Check
Remark
8191 3 [Turn over
(b) Carry out your procedure. Present your results in a suitable table and calculate the average titre.
[8]
(c) State the colour change at the end point of the titration.
From to [2]
TeacherMark
Examiner Check
Remark
8191 4
(d) With reference to the following equation explain the reason for adding the pH10 buffer to the reaction mixture.
Mg21 1 H2(edta)22 [Mg(edta)]22 1 2H1
[2]
(e) Calculate the concentration of the magnesium ions in the hard water in mg dm23.
[5]
(f) A solution of magnesium ions can be used to distinguish between solutions of carbonate and hydrogencarbonate ions. State the expected observations.
[2]
TeacherMark
Examiner Check
Remark
8191 5 [Turn over
2 Observation/deduction
Safety glasses must be worn at all times and care should be exercised during this practical examination.
(a) You are provided with a salt, labelled R. Carry out the following tests. Record your observations and deductions in the spaces below.
Test Observations Deductions
1 Describe the appearance of R.
[1] [1]
2 Add a spatula measure of R to 50 cm3 of deionised water and stir until there is no further change.
[1] [1]
3 Add 5 drops of silver nitrate solution to a test tube containing 2 cm3 of the solution of R. Allow the mixture to stand.
[3] [1]
4 Put 2 cm3 of the solution of R into a test tube.
(a) Add 5 drops of sodium hydroxide solution and allow to stand.
(b) Add a further 5 cm3 of sodium hydroxide solution.
[4] [2]
5 Place a spatula measure of solid R in a dry boiling tube and heat gently.
[2] [1]
Give the name of compound R
[2]
TeacherMark
Examiner Check
Remark
8191 6
(b) You are provided with an organic liquid containing one functional group, labelled S. Carry out the following tests and record your observations and deductions in the spaces below. The mass spectrum of S is also provided.
Test Observations Deductions
1 Place 2 cm3 of S into a boiling tube. Place in a test tube rack.
(a) Under supervision, cautiously add a very small measure of phosphorus(V) chloride in a fume cupboard.
(b) In a fume cupboard, hold the stopper of a bottle of concentrated ammonia solution over the boiling tube used in test 1(a).
[2]
[1]
[1]
[1]
2 Place 2 cm3 of S into a test tube. Add 1 cm3 of sodium carbonate solution.
[1] [1]
(i) What homologous series does S belong to?
[1]
TeacherMark
Examiner Check
Remark
8191 7 [Turn over
Use the following mass spectrum to deduce the structure of S.
10 15 20 25 30 35 40 45 50 55 60 65 70 75
100
80
60
40
20
0
m/z
rela
tive
abun
danc
e
(ii) Draw the structure of S below.
[1]
Maximum [25] marks
TeacherMark
Examiner Check
Remark
8191 8
3 Planning exercise
Preparation of aspirin
Aspirin can be prepared by reacting 2-hydroxybenzoic acid with ethanoic anhydride in the presence of concentrated phosphoric(V) acid. The product has a melting point of 135 °C.
COOH
OH
� (CH3CO)
2O
COOH
O — C — CH3
O
� CH3COOH
The following method can be used:
Place 20.0 g of 2-hydroxybenzoic acid in a pear-shaped flask and add 40 cm3 of ethanoic anhydride. Safely add 5 cm3 of concentrated phosphoric(V) acid to the mixture. Heat under reflux. Add water to hydrolyse any unreacted ethanoic anhydride to form ethanoic acid. Pour the mixture onto 400 g of crushed ice in a beaker. The product is removed by suction filtration, recrystallised from water and dried in a desiccator. The melting point is then determined.
(a) (i) Suggest the role of the concentrated phosphoric(V) acid.
[1]
(ii) Explain how you would safely add the concentrated phosphoric(V) acid.
[2]
TeacherMark
Examiner Check
Remark
8191 9 [Turn over
(b) (i) What is meant by the term reflux?
[1]
(ii) Draw a labelled diagram showing the apparatus used for refluxing.
[3]
(c) Write an equation for the hydrolysis of ethanoic anhydride.
[2]
(d) Why is the mixture poured onto ice?
[1]
(e) Why is suction filtration used rather than gravity filtration?
[1]
TeacherMark
Examiner Check
Remark
8191 10
(f) Describe how the impure product is recrystallised.
[3]
Quality of written communication [2]
(g) Assuming a 65% yield, calculate the mass of 2-hydroxybenzoic acid required to form 5.0 g of pure aspirin.
[4]
THIS IS THE END OF THE QUESTION PAPER
113043
Permission to reproduce all copyright material has been applied for.In some cases, efforts to contact copyright holders may have been unsuccessful and CCEAwill be happy to rectify any omissions of acknowledgement in future if notified.
MARKSCHEME
Standardising Meeting Version
8191.01 F
ADVANCEDGeneral Certificate of Education
2013
ChemistryAssessment Unit A2 3
Internal AssessmentPractical Examination 2
[AC232]
THURSDAY 16 MAY, MORNING
2
AVAILABLE MARKS
8191.01 F
Annotation
1. Please do all marking in red ink.
2. All scripts should be checked for mathematical errors. Please adopt a system of one tick () equals 1 mark, e.g. if you have awarded 4 marks for part of a question then 4 ticks () should be on this candidate’s answer.
3. The total mark for each question should be recorded in a circle placed opposite the question number in the teacher mark column.
4. As candidates have access to scripts please do not write any inappropriate comments on their scripts.
General points
• All calculations are marked according to the number of errors made.
• Errors can be carried through. If the wrong calculation is carried out then the incorrect answer can be carried through. One mistake at the start of a question does not always mean that all marks are lost.
• Any number of decimal places may be used provided the ‘rounding’ is correct.
• Listing is when more than one answer is given for a question that only requires one answer, e.g. the precipitate from a chloride with silver nitrate is a white solid; if the candidate states a white or a cream solid, one answer is correct and one answer is wrong. Hence they cancel out.
• Although names might be in the mark scheme it is generally accepted that formulae can replace them. Formulae and names are often interchangeable in chemistry.
• The marking of colours is defined in the ‘CCEA GCE Chemistry Acceptable Colours’ document.
MARKING GUIDELINES
Interpretation of the Mark Scheme
• Carry error through This is where mistakes/wrong answers are penalised when made, but if carried into further steps of the question, then no further penalty is applied. This pertains to calculations and observational/deduction exercises. Please annotate candidates’ answers by writing the letters c.e.t. on the appropriate place in the candidates’ answers.
• Oblique/forward slash This indicates an acceptable alternative answer(s).
• Brackets Where an answer is given in the mark scheme and is followed by a word/words in brackets, this indicates that the information within the brackets is non-essential for awarding the mark(s).
3
AVAILABLE MARKS
8191.01 F
1 Titration exercise
(a) Rinse out a pipette with the hard water and transfer 25.0 cm3 of the hard water into a (conical) flask [1] Add a portion of pH10 buffer solution [1] Add 4 drops of Eriochrome Black T to the conical flask and swirl [1] Rinse out the burette with the edta solution and fill the burette [1] Titrate with/add the edta solution from the burette until colour matches reference sample [1] Rough and two/three accurate titrations [1]
To a maximum of [6] [6]
(b) Table [3] The Table should be drawn as a table. It should be labelled with the following: initial burette reading, final burette reading and the titre. It is not necessary to use exactly these words but there should be appropriate columns and rows. The recorded readings should be checked for mathematical accuracy. [1].
The rough titration value should be greater than the accurate values (no more than 2 cm3) [1].
Units, i.e. cm3, should be stated [1].
Use of decimal places [2] All burette readings should be to at least one decimal place – each mistake is penalised by one mark. (However initial burette readings of 0 are penalised once only.)
If used, the second decimal place position should be 0 or 5 only – other values will be penalised by 1 mark for each.
Average titre [2] Accurate titrations only should be used. The use of a rough value is [–1]. The average value can be calculated to two decimal places or more, e.g. 25.15 and 25.20 average to 25.175. If three accurate titres are recorded, then the average titre must be calculated using all three accurate titres.
Any error is [–1]. This might be an incorrect calculation or the omission of units. If the average titre is included in the table then the units indicated on the table apply.
Titration consistency [1] This is the difference within the accurate titrations. If three accurate values are given then the difference between highest and lowest is used.
Difference Mark ±0.1 [1] >0.1 [0] [8]
4
AVAILABLE MARKS
8191.01 F
(c) red [1] to blue [1] [2]
(d) to remove H+ [1] and prevent reverse of equilibrium [1] [2]
(e) assuming an average titre of 22.8 cm3
moles edta = (22.8 × 0.02)/1000 = 4.56 × 10–4
moles Mg2+ = 4.56 × 10–4 concentration of Mg2+ = (4.56 × 10–4 × 1000)/25 = 0.0182 mol dm–3
mass Mg2+ = 0.018 × 24 = 0.437 g concentration of Mg2+ = 437 mg dm–3 [–1] each error [5]
Consequential marking/carry error through (cet) to be applied in calculations.
(f) carbonate – white precipitate [1] hydrogencarbonate – no precipitate/solution remains colourless [1] [2] 25
5
AVAILABLE MARKS
8191.01 F
2 Observation/deduction
There are 28 scoring points available in Question 2. However the maximum mark for this question is 25. Please see additional notes at the end of Question 2.
If the candidate scores more than 25 then MAX 25 should be written at beginning of question in the teacher mark column.
(a)
Test Observations Deductions
1 Describe the appearance of R. pink [1] solid
Transition metal compound or ion [1]
2 Add a spatula measure of R to approximately 50 cm3 of deionised water and stir until there is no further change.
colourless/pale pink solution [1] Mn2+/Co2+ [1]
3 Add 5 drops of silver nitrate solution to a test tube containing 2 cm3 of the solution of R. Allow the mixture to stand.
white [1] ppt [1]in pale pink/colourless solution [1] chloride ion present [1]
4 Put 2 cm3 of the solution of R into a test tube.
(a) Add 5 drops of sodium hydroxide solution and allow to stand.
(b) Add a further 5 cm3 of sodium hydroxide solution.
white [1] ppt [1] turns brown/black/darkens [1]
ppt remains [1]
insoluble hydroxide [1]
Mn2+/Mn(OH)2 / Mn(OH)2 (H2O)4 [1]
5 Place a spatula measure of solid R in a dry boiling tube and heat gently.
colourless liquidon sides of tube [1]crystals changecolour [1]
hydrated/water of crystallisation present [1]
Give the name of compound R
hydrated [1] manganese(ll) chloride [1] [2]
6
AVAILABLE MARKS
8191.01 F
(b)
Test Observations Deductions
1 Place 2 cm3 of S into a boiling tube. Place in a test
tube rack.
(a) Under supervision, cautiously add a very small measure of phosphorus(V) chloride, in a fume cupboard.
(b) In a fume cupboard, hold the stopper of a bottle of concentrated ammonia solution over the boiling tube used in test 1(a).
steamy fumes [1]effervescence [1]
white smoke [1]
–OH group present [1]
HCI [1]
2 Place 2 cm3 of S into a test tube. Add 1 cm3 of sodium carbonate solution. fizz/effervescence [1] S is acidic [1]
(i) What homologous series does S belong to?
carboxylic acids [1]
(ii) Structure of S
HO
OH
C C
H
H
[1] Max 25
7
AVAILABLE MARKS
8191.01 F
General:
An incorrect deduction can be carried through to naming the salt. A deduction based on an incorrect observation can be credited on the basis of c.e.t.
Wrong placing of answers
In the observation/deduction question candidates may write their answers in the wrong column. This is not penalised, e.g. a deduction written in the observation column may be credited, if correct.
Further observations
Candidates may record observations not recorded in the mark scheme, but credit should only be given to those observations recorded in the mark scheme.
Question 2 (a)
Test 1 Crystals is acceptable but not powder. “Transition metal ion/compound” is OK. “Transition metal” is wrong. At this point the word ‘possibly’ or similar should be used if stating possible ions. Both Mn2+ and Co2+ are pink but since Mn2+ is a much paler shade of pink it would be acceptable at this point to suggest that Mn2+ is possibly present without mention of Co2+. Ions must either be given their correct symbol and charge or be referred to as an ion (e.g. “Mn2+” or “manganese ions” are acceptable; “Mn” or “manganese” are not acceptable).
Test 2 The solution is an extremely pale pink colour so “colourless” is also acceptable.Candidates can score here for the same deduction made in Test 1. No mark is awarded for deducing that R is soluble as it is referred to as a “solution” in later tests.
Test 3 When allowed to stand a white precipitate will settle at the bottom of the test tube. No other colour is acceptable. “Chloride” or “chloride ion” or “Cl–” are acceptable. “Chlorine” or “CI” are not acceptable.
Test 4(a) The list of acceptable colours states that the precipitate formed, Mn(OH)2,is white. However, since it darkens so quickly, the precipitate could legitimately be observed as being cream or beige and these are also acceptable. The list of acceptable colours states that the precipitate turns brown/black on standing but it is acceptable to observe that the precipitate “darkens”.
Test 5 The most important observation is the formation of the colourless liquid on the walls of the boiling tube indicating the presence of water of crystallisation, but since the crystals do change colour then this is also accepted. The actual colour is not important. If the only observation is the colour change of the crystals the candidate cannot score a mark for deduction.
Name of R The oxidation state (II) is not necessary but if an incorrect oxidation state is given then a mark is lost.
Question 2 (b)
Test 1(b) The observation could also be described as white fumes.
8
AVAILABLE MARKS
8191.01 F
3 Planning Exercise
(a) (i) catalyst [1]
(ii) slowly/dropwise [1] gloves [1] [2] (b) (i) repeated boiling and condensing of a reaction mixture [1]
(ii)
heat
reaction mixture
water in
water out condenser
no heat source [–1] no double jacket on condenser [–1] condenser sealed at top [–1] top of flask open [–1] no labels [–1] [3]
(c) (CH3CO)2O + H2O → 2 CH3COOH [2]
(d) to form crystals/solid/product [1]
(e) faster/gives drier product [1]
(f) dissolve in minimum volume of hot water [1] filter [1] cool [1] [3] Quality of written communication [2]
(g) number of moles aspirin = 5 ÷ 180 = 0.028 0.0278 ÷ 65 × 100 = 0.043 number of moles 2-hydroxybenzoic acid = 0.043 mass 2-hydroxybenzoic acid = 0.043 × 138 = 5.9 g [4] 20
Total 70
TIME2 hours 30 minutes.
INSTRUCTIONS TO CANDIDATESWrite your Centre Number and Candidate Number in the spaces provided at the top of this page.Answer all three questions.Write your answers in the spaces provided.
INFORMATION FOR CANDIDATESThe total mark for this paper is 70.Questions 1 and 2 are practical exercises each worth 25 marks.Question 3 is a planning exercise worth 20 marks.Quality of written communication will be assessed in Question 3(b).You may not have access to notes, textbooks and other material to assist you.A Periodic Table of the Elements, containing some data, is included in this question paper.
ADVANCEDGeneral Certifi cate of Education
2014
8812
Chemistry
Assessment Unit A2 3Internal Assessment
Practical Examination 1
[AC231]
THURSDAY 15 MAY, MORNING
Centre Number
71
Candidate Number
AC231
For Examiner’s use only
QuestionNumber
Examiner Mark Remark
123
TotalMarks
8812 2
Examiner Only Marks Remark
1 Titration exercise
You are required to dissolve a weighed sample of ammonium iron(II) sulfate in dilute sulfuric acid and make the solution up to 250 cm3 in a volumetric flask. You will then titrate 25.0 cm3 portions of this solution with acidified potassium manganate(VII). You will then use your results to calculate the concentration of the acidified potassium manganate(VII) solution.
You are provided with:
• Hydrated ammonium iron(II) sulfate, (NH4)2Fe(SO4)2.6H2O • Dilute sulfuric acid • Deionised water • A 250 cm3 volumetric flask • An acidified solution of potassium manganate(VII).
(a) (i) Weigh out between 7.80 g and 7.90 g of ammonium iron(II) sulfate. Record the mass to two decimal places.
Mass of (NH4)2Fe(SO4)2.6H2O [2]
(ii) Dissolve the weighed sample in approximately 100 cm3 of dilute sulfuric acid and make the solution up to 250 cm3 in the volumetric flask using deionised water. Calculate the concentration of the solution in mol dm–3.
[3]
8812 3 [Turn over
Examiner Only Marks Remark
(b) Titrate 25.0 cm3 portions of your solution with acidified potassium manganate(VII). Record your results in a suitable table in the space below. Calculate the average titre.
[8]
(c) (i) Describe how you ensured the end point of your titration was accurate.
[2]
(ii) State the colour change at the end point of your titration.
[1]
8812 4
Examiner Only Marks Remark
(d) (i) Write the half-equation for the reduction of acidified manganate(VII) ions to form manganese(II) ions.
[2]
(ii) Write the half-equation for the oxidation of iron(II) ions to iron(III) ions.
[1]
(iii) Write the ionic equation for the reaction.
[2]
(iv) Calculate the concentration of the acidified potassium manganate(VII) solution in g dm–3.
[4]
8812 5 [Turn over
BLANK PAGE
(Questions continue overleaf)
8812 6
Examiner Only Marks Remark
2 Observation/deduction
Safety glasses must be worn at all times and care should be exercised during this practical examination.
(a) (i) You are provided with a solid, labelled A. Carry out the following tests. Record your observations in the spaces below.
(ii) Identify A.
[2]
Test Observations
1 Describe the appearance of A.
[1]
2 Dissolve two spatula measures of A in approximately 50 cm3 of water.
Keep this solution for use in further tests.
[1]
3 Place 4 cm3 of the solution from test 2 in a test tube.
Add an equal volume of concentrated hydrochloric acid.
[1]
4 Place 4 cm3 of the solution from test 2 in a test tube.
Add an equal volume of 1,2-diaminoethane solution. [1]
5 (a) Place 4 cm3 of the solution from test 2 in a test tube. Slowly add an equal volume of sodium hydroxide solution.
(b) Add a further 5 cm3 of sodium hydroxide solution. [2]
6 Place 4 cm3 of the solution from test 2 in a test tube. In a fume cupboard, add an equal volume of concentrated ammonia solution.
[1]
7 Place 4 cm3 of the solution from test 2 in a test tube. Add 1 cm3 of barium chloride solution dropwise.
[1]
8812 7 [Turn over
Examiner Only Marks Remark
(iii) Suggest the formulae of the complex ions formed in tests 2, 3, 4 and 6.
Test 2 ___________________________________________ [1]
Test 3 ___________________________________________ [1]
Test 4 ___________________________________________ [1]
Test 6 ___________________________________________ [1]
(iv) Give the formulae of the precipitates formed in tests 5 and 7.
Test 5 ___________________________________________ [1]
Test 7 ___________________________________________ [1]
8812 8
Examiner Only Marks Remark
(b) (i) You are provided with an aqueous solution of an organic compound B. Carry out the following tests. Record your observations in the spaces below.
(ii) Identify the functional group present in B.
[1]
(iii) Suggest how the infrared spectrum of B could confirm the presence of this functional group.
[2]
(iv) Suggest how the mass spectrum of B could confirm its identity.
[2]
Test Observations
1 Describe the solution. Include a description of its smell.
[1]
2 Place 4 cm3 of the solution in a test tube. Add an equal volume of potassium dichromate solution and acidify with 1 cm3 of dilute sulfuric acid. Heat in a water bath for five minutes.
[1]
3 Place 4 cm3 of the solution in a test tube. Add half a spatula measure of sodium hydrogencarbonate.
[2]
8812 9 [Turn over
BLANK PAGE
(Questions continue overleaf)
8812 10
Examiner Only Marks Remark
3 Planning exercise
Ethyl methanoate, HCOOCH2CH3, exists as a liquid at room temperature and pressure. Its boiling point is 55 °C and its density is 0.9 g cm–3.
(a) (i) Write the equation for the formation of ethyl methanoate from methanoic acid and ethanol.
[1]
(ii) Assuming a 60% yield, calculate the minimum mass of each reactant required to produce 4.44 g of ethyl methanoate.
[3]
(b) Describe the laboratory preparation of ethyl methanoate up to and including the removal of the crude product from the reaction mixture.
[5]
Quality of written communication [2]
8812 11
Examiner Only Marks Remark
(c) The crude product can be purified using an aqueous solution of sodium carbonate followed by anhydrous calcium chloride.
(i) Why and how is the sodium carbonate solution used?
[4]
(ii) Why and how is the anhydrous calcium chloride used?
[2]
8 [Turn over
8812 12
Examiner Only Marks Remark
(d) Part of the nmr spectrum of ethyl methanoate is shown below. Complete the nmr spectrum in terms of integration and splitting pattern.
[3]
9 8 7 6 5 4 3 2 1 0
ppm
THIS IS THE END OF THE QUESTION PAPER
8812
Permission to reproduce all copyright material has been applied for.In some cases, efforts to contact copyright holders may have been unsuccessful and CCEAwill be happy to rectify any omissions of acknowledgement in future if notifi ed.
ADVANCEDGeneral Certificate of Education
2014
Chemistry
Assessment Unit A2 3Internal Assessment
Practical Examinations 1 and 2[AC231] [AC232]
THURSDAY 15 MAY AND FRIDAY 16 MAY
8812.02
APPARATUSAND
MATERIALSLIST
*AC231**AC232*
AC
231
AC
232
8812.02 22 [Turn over
Advice for centres
● All chemicals used should be at least laboratory reagent specification and labelled with appropriate safety symbols, e.g. irritant.
● For centres running multiple sessions – candidates for the later session should be supplied with clean, dry glassware. If it is not feasible then glassware from the first session should be thoroughly washed, rinsed with deionised water and allowed to drain.
● Ensure all chemicals are in date otherwise expected observations may not be seen.
8812.02 3 3
Practical Examination 1
Each candidate must be supplied with safety goggles or glasses.
Question 1
Each candidate must be supplied with:
• one 50 cm3 burette of at least class B quality
• one 25 cm3 pipette of at least class B quality
• one 250 cm3 volumetric fl ask
• a safety pipette fi ller
• three conical fl ask of 250 cm3 capacity
• a funnel for fi lling the burette (optional)
• a white tile or white paper
• 250 cm3 beaker
• a wash bottle containing deionised water
• a retort stand and clamp
• weighing bottle (or equivalent)
• approximately 9.0 g of ammonium iron(II) sulfate
• access to an accurate balance (reading to 2 decimal places)
• glass rod
• spatula
• 250 cm3 of dilute sulfuric acid (approximately 1.0 mol dm–3) labelled dilute sulfuric acid and caution
• 150 cm3 of 0.02 mol dm–3 acidifi ed potassium manganate(VII) labelled potassium manganate(VII) solution.
8812.02 44 [Turn over
Practical Examination 1
Question 2
Each candidate must be supplied with:
• a small beaker
• fi ve test tubes
• a boiling tube
• a test tube holder
• a test tube rack
• a spatula
• a stirring rod
• a heat-proof mat
• a Bunsen burner
• several plastic droppers
• deionised water
• kettle to supply hot water (optional)
• hydrated copper(II) sulfate (approximately 3.0 g) labelled A
• about 10 cm3 of concentrated hydrochloric acid in a stoppered reagent bottle labelled concentrated hydrochloric acid and corrosive
• about 10 cm3 of an aqueous solution of 1,2-diaminoethane (approximately 0.2M) labelled 1,2-diaminoethane
• about 10 cm3 of an aqueous solution of sodium hydroxide (approximately 2.0M) labelled sodium hydroxide and corrosive
• a reagent bottle containing concentrated ammonia labelled concentrated ammonia and irritant (available in the fume cupboard(s)). Each candidate will only need about 10 cm3
• about 10 cm3 of aqueous solution of barium chloride (approximately 0.1M) labelled barium chloride solution
• about 10 cm3 of aqueous ethanoic acid (approximately 25% glacial 75% water) labelled B
• about 10 cm3 of aqueous potassium dichromate (approximately 0.1M) labelled potassium dichromate and irritant
• 2M sulfuric acid labelled dilute sulfuric acid and caution
• 2–3 g of sodium hydrogencarbonate
8812.02 5 5
Practical Examination 2
Each candidate must be supplied with safety goggles or glasses.
Question 1
Each candidate must be supplied with:
• one 50 cm3 burette of at least class B quality
• one 25 cm3 pipette of at least class B quality
• one 250 cm3 volumetric fl ask
• a safety pipette fi ller
• three conical fl ask of 250 cm3 capacity
• a funnel for fi lling the burette (optional)
• a white tile or white paper
• one beaker of 250 cm3 capacity
• a wash bottle containing deionised/distilled water
• a retort stand and clamp
• weighing bottle (or equivalent)
• approximately 9.0 g of ammonium iron(II) sulfate
• access to an accurate balance (reading to 2 decimal places)
• glass rod
• spatula
• 250 cm3 of dilute sulfuric acid (approximately 1.0 mol dm–3) labelled dilute sulfuric acid and caution
• 150 cm3 of 0.02 mol dm–3 acidifi ed potassium manganate(VII) labelled potassium manganate(VII) solution.
8812.02 66 [Turn over
Practical Examination 2
Question 2
Each candidate must be supplied with:
• a small beaker
• fi ve test tubes
• a boiling tube
• a test tube holder
• a test tube rack
• a spatula
• a stirring rod
• a heat-proof mat
• a Bunsen burner
• several plastic droppers
• deionised water
• kettle to supply hot water (optional)
• hydrated nickel(II) sulfate (approximately 3.0 g) labelled X
• about 10 cm3 of an aqueous solution of edta (approx 0.1M) labelled edta
• about 10 cm3 of an aqueous solution of 1,2-diaminoethane (approximately 0.2M) labelled 1,2-diaminoethane
• about 10 cm3 of an aqueous solution of sodium hydroxide (approximately 2.0M) labelled sodium hydroxide
• a reagent bottle containing concentrated ammonia labelled concentrated ammonia and irritant (available in the fume cupboard(s)). Each candidate will only need about 10 cm3
• about 10 cm3 of aqueous solution of barium chloride (approximately 0.1M) labelled barium chloride solution
• about 10 cm3 of aqueous ethanoic acid (approximately 25% glacial 75% water) labelled Y
• about 10 cm3 of potassium dichromate (approximately 0.1M) labelled potassium dichromate and irritant
• 2M sulfuric acid labelled dilute sulfuric acid and caution
• 2–3 g of sodium hydrogencarbonate
8812.02 88 [Turn over
8812.03 [Turn over
ADVANCEDGeneral Certificate of Education
2014
Chemistry
Assessment Unit A2 3Internal Assessment
Practical Examinations 1 and 2
[AC231] [AC232]
THURSDAY 15 AND FRIDAY 16 MAY
Confidential Instructionsto the Supervisor
of the Practical Examination
8812.03 [Turn over
INSTRUCTIONS TO THE SUPERVISOR OF THE PRACTICAL EXAMINATION
General
1. The instructions contained in this document are for the use of the Supervisor and are strictly confidential. Under no circumstances may information concerning apparatus or materials be given before the examination to a candidate or other unauthorised person.
2. In a centre with a large number of candidates it may be necessary for two or more examination sessions to be organised. It is the responsibility of the schools to ensure
that there should be no contact between candidates taking each session.
3. A suitable laboratory must be reserved for the examination and kept locked throughout the period of preparation. Unauthorised persons not involved in the preparation for the examination must not be allowed to enter. Candidates must not be admitted until the specified time for commencement of the examination.
4. The Supervisor must ensure that the solutions provided for the candidates are of the nature and concentrations specified in the Apparatus and Materials List.
5. The Supervisor is to be granted access to the Teacher’s Copy of the Question Paper, showing parts of questions 1 and 2 only, on Monday 12 May 2014. The Supervisor is asked to check, at the earliest opportunity, that the experiments and tests in the question paper may be completed satisfactorily using the apparatus, materials and solutions that have been assembled. This question paper must then be returned to safe custody at the earliest possible moment after the Supervisor has ensured that all is in order. No access to the question paper should be allowed before 12 May 2014.
6. In the case of centres who have candidates entered for both practical examinations, the Supervisor must return all unused scripts of Practical Examination 1 to the Examinations Officer immediately on completion of the examination. The contents of
this examination must be kept confidential until the completion of Practical Examination 2.
7. Pipettes and burettes should be checked before the examination, and there should be an adequate supply of spare apparatus in case of breakages. The Apparatus and Materials List should be regarded as a minimum and there should be no objection to candidates being supplied with more than the minimum amount of apparatus and materials.
8. Candidates may not use text books and laboratory notes for reference during the examination, and must be informed of this beforehand.
8812.03 [Turn over
9. Clear instructions must be given by the Supervisor to all candidates at the beginning of the examination concerning appropriate safety procedures and precautions. Supervisors are also advised to remind candidates that all substances in the examination must be treated with caution. Only those tests specified in the question paper should be attempted. Candidates must not attempt any additional confirmatory tests. Anything
spilled on the skin should be washed off immediately with plenty of water. The use of appropriate eye protection is essential.
10. Supervisors are reminded that they may not assist candidates during the examination. However, if in the opinion of the Supervisor, a candidate is about to do something which may endanger him/herself or others, the Supervisor should intervene. A full written report must be sent to CCEA at once.
11. Upon request, a candidate may be given additional quantities of materials (answer paper, reagents and unknowns) without penalty. No notification need be sent to CCEA.
12. The examination room must be cleared of candidates immediately after the examination.
13. No materials will be supplied by CCEA.
8812.03 [Turn over
Northern Ireland Council for the Curriculum, Examinations andAssessment
General Certificate of Education
Advanced
Chemistry
Practical Examination 1
Thursday 15 May 2014
This report must be completed by the Supervisor during the examination.The complete report should include all candidates taking this PracticalExamination. This Supervisor’s Report should be copied and attached toEach Advice Note bundle and returned to CCEA in the normal way.
Comments:
Supervisor’s Signature . . . . . . . . . . . . . . . . . . . Date . . . . . . . . . . .
71
Centre Number
Candidate Number
8812.03 [Turn over
Northern Ireland Council for the Curriculum, Examinations andAssessment
General Certificate of Education
Advanced
Chemistry
Practical Examination 2
Friday 16 May 2014
This report must be completed by the Supervisor during the examination.The complete report should include all candidates taking this PracticalExamination. This Supervisor’s Report should be copied and attached toEach Advice Note bundle and returned to CCEA in the normal way.
Comments:
Supervisor’s Signature . . . . . . . . . . . . . . . . . . . Date . . . . . . . . . . .
71
Centre Number
Candidate Number
8812.03
ADVANCEDGeneral Certificate of Education
2014
8812.01F
MARKSCHEME
ChemistryAssessment Unit A2 3
Internal AssessmentPractical Examination 1
[AC231]
THURSDAY 15 MAY, MORNING
8812.01F 22 [Turn over
AVAILABLEMARKS
Annotation
1. Please do all marking in red ink.
2. All scripts should be checked for mathematical errors. Please adopt a system of one tick () equals 1 mark, e.g. if you have awarded 4 marks for part of a question then 4 ticks () should be on this candidate’s answer.
3. The total mark for each question should be recorded in a circle placed opposite the question number in the teacher mark column.
4. As candidates have access to scripts please do not write any inappropriate comments on their scripts.
General points
• All calculations are marked according to the number of errors made.
• Errors can be carried through. If the wrong calculation is carried out then the incorrect answer can be carried through. One mistake at the start of a question does not always mean that all marks are lost.
• Any number of decimal places may be used provided the ‘rounding’ is correct.
• Listing is when more than one answer is given for a question that only requires one answer, e.g. the precipitate from a chloride with silver nitrate is a white solid; if the candidate states a white or a cream solid, one answer is correct and one answer is wrong. Hence they cancel out.
• Although names might be in the mark scheme it is generally accepted that formulae can replace them. Formulae and names are often interchangeable in chemistry.
• The marking of colours is defined in the ‘CCEA GCE Chemistry Acceptable Colours’ document.
MARKING GUIDELINES
Interpretation of the Mark Scheme
• Carry error through This is where mistakes/wrong answers are penalised when made, but if carried
into further steps of the question, then no further penalty is applied. This pertains to calculations and observational/deduction exercises. Please annotate candidates’ answers by writing the letters c.e.t. on the appropriate place in the candidates’ answers.
• Oblique/forward slash This indicates an acceptable alternative answer(s).
• Brackets Where an answer is given in the mark scheme and is followed by a word/words in
brackets, this indicates that the information within the brackets is non-essential for awarding the mark(s).
8812.01F 3 3
AVAILABLEMARKS
1 (a) (i) Mass between given values Mass to 2 decimal places Units Error [–1] [2]
(ii) Correct RFM for ammonium iron(II) sulfate (392) Correct calculation of moles Correct calculation of concentration Error [–1] [3] (b) Table [3] Significant figures [2] Calculation of average titre [2] Titration consistency [1] [8]
Table
Titration Initial burette reading/cm3
Final burette reading/cm3
Addedvolume/cm3
1
2
3 Average titre = cm3
Clearly labelled and neatly presented table, including units and the recording of the average titre. [3]
Significant figures All accurate titration readings recorded to one decimal place (including initial burette reading at 0.0 if used). Accept, however, 0.00 and 0.05 but penalise by [–1] if other readings are given to two or more decimal places. The use of 0 is penalised by [–1] if used (only penalise once). [2] Average titre Accurate titrations only should be used. The use of a rough value is [–1].
The average value can be calculated to two decimal places or more, e.g. 25.17 and 25.18 average to 25.175.
If three accurate titres are recorded, then the average titre must be calculated using all three accurate titres.
Any error is [–1]. This might be an incorrect calculation or the omission of units. If the average titre is included in the table then the units indicated on the table apply.
Titration consistency
Difference Mark ±0.1 [1] >0.1 [0]
8812.01F 44 [Turn over
AVAILABLEMARKS
(c) (i) Add solution from burette slowly/dropwise at end point [1], swirl the flask/wash down sides with deionised water etc. [1] [2] (ii) colourless to pink [1]
(d) (i) MnO4– + 8H+ + 5e– → Mn 2+ + 4H2O [2]
(ii) Fe2+ → Fe3+ + e– [1]
(iii) 5Fe2+ + 8H+ + MnO4– → 5Fe3+ + 4H2O + Mn2+ [2]
(iv) for a concentration of 0.09 mol dm–3 Fe2+ and a titration value of 20.1 cm3
25/1000 × 0.09 mol in 25 cm3 of Fe2+ solution = 2.25 × 10–3 mol
2.25 × 10–3/5 mol KMnO4 in 20.1 cm3 = 4.5 × 10–4 mol in 20.1 cm3
KMnO4 = 158; 4.5 × 10–4 mol = 158 × 4.5 × 10–4 g = 0.0711 g
0.0711 g in 20.1 cm3 = 0.0711/20.1 × 103 = 3.537 g = 3.54 g [4] 25
8812.01F 5 5
AVAILABLEMARKS
2 Observation/deduction
Safety glasses must be worn at all times and care should be exercised during this practical examination.
(a) (i) You are provided with a solid, labelled A. Carry out the following tests. Record your observations in the spaces below.
Test Observations
1 Describe the appearance of A. Blue solid/crystals/powder[1]
2 Dissolve two spatula measures of A in approximately 50 cm3 of water.
Keep this solution for use in further tests.Blue (solution)
[1]
3 Place 4 cm3 of the solution from test 2 in a test tube. Add an equal volume of concentrated hydrochloric acid. Yellow-green/Green solution
[1]4 Place 4 cm3 of the solution from test 2
in a test tube. Add an equal volume of 1,2-diaminoethane solution. Darker blue solution/
blue-violet/blue-purple[1]
5 (a) Place 4 cm3 of the solution from test 2 in a test tube. Slowly add an equal volume of sodium hydroxide solution.
(b) Add a further 5 cm3 of sodium hydroxide solution.
Blue precipitate
Precipitate remains[2]
6 Place 4 cm3 of the solution from test 2 in a test tube. In a fume cupboard, add an equal volume of concentrated ammonia solution.
Deep blue solution forms[1]
7 Place 4 cm3 of the solution from test 2 in a test tube. Add 1 cm3 of barium chloride solution dropwise. White precipitate
[1]
(ii) hydrated [1] copper(II) sulfate [1] [2]
(iii) Suggest the formulae of the complex ions formed in tests 2, 3, 4 and 6.
Test 2 [Cu(H2O)6]2+ [1]
Test 3 [CuCl4]2– [1]
Test 4 [Cu(en)3]2+ [1]
Test 6 [Cu(NH3)4(H2O)2]2+ [1] [4]
8812.01F 66 [Turn over
AVAILABLEMARKS
(iv) Give the formula of the precipitates formed in tests 5 and 7.
Test 5 Cu(OH)2 [1]
Test 7 BaSO4 [1] [2]
(b) (i) You are provided with an aqueous solution of an organic compound B. Carry out the following tests. Record your observations in the spaces below.
Test Observations
1 Describe the solution. Include a description of its smell.
ColourlessVinegar smell/sharp/irritating
[1]
2 Place 4 cm3 of the solution in a test tube. Add an equal volume of potassium dichromate solution and acidify with 1 cm3 of dilute sulfuric acid. Heat in a water bath for 5 minutes.
Solution remains orange [1]
3 Place 4 cm3 of the solution in a test tube. Add half a spatula measure of sodium hydrogencarbonate.
Solid dissolvesbubbles/effervescence/fizzing
[2]
(ii) –COOH [1]
(iii) strong C O absorption [1] strong O H absorption [1] [2]
(iv) position of molecular ion gives RMM [1] uniqueness of fragmentation [1] [2] 25
8812.01F 7 7
AVAILABLEMARKS
3 Planning Exercise (a) (i) HCOOH + C2H5OH → HCOOC2H5 + H2O [1] (ii) Theoretical yield = 7.4 g or 0.1 mole [1] Min mass of ethanol 4.6 g [1] Min mass of methanoic acid 4.6 g [1] [3]
(b) Place ethanol and methanoic acid in a flask [1] add concentrated sulfuric acid [1] add anti-bumping granules (or equivalent) [1] reflux/distillation [1] collect crude product around 55 °C [1] [5]
Quality of written communication [2] (c) (i) Used to remove acid impurities [1] Shake the crude product with aqueous sodium carbonate [1] using a separating funnel and release pressure [1] separate the ester from the aqueous layer [1] [4]
(ii) Used to remove water [1] shake with anhydrous calcium chloride until clear and filter/decant [1] [2]
(d)
9 8 7 6 5 4 3 2 1 0
quartet and triplet [1] triplet closer to TMS [1] integration (2:3) [1] [3] 20
Total 70
ppm
TIME2 hours 30 minutes.
INSTRUCTIONS TO CANDIDATESWrite your Centre Number and Candidate Number in the spaces provided at the top of this page.Answer all three questions.Write your answers in the spaces provided.
INFORMATION FOR CANDIDATESThe total mark for this paper is 70.Questions 1 and 2 are practical exercises each worth 25 marks.Question 3 is a planning exercise worth 20 marks.Quality of written communication will be assessed in Question 3(b).You may not have access to notes, textbooks and other material to assist you.A Periodic Table of the Elements, containing some data, is included in this question paper.
ADVANCEDGeneral Certificate of Education
2014
8813.03 R
For Examiner’s use only
Question Number
Examiner Mark Remark
123
TotalMarks
Chemistry
Assessment Unit A2 3Internal Assessment
Practical Examination 2
[AC232]
FRIDAY 16 MAY, MORNING
Centre Number
71
Candidate Number
*AC232*
AC
232
8813.03 R 2
Examiner Only Marks Remark
1 Titration exercise
You are required to dissolve a weighed sample of ammonium iron(II) sulfate in dilute sulfuric acid and make the solution up to 250 cm3 in a volumetric flask. You will then titrate 25.0 cm3 portions of this solution with acidified potassium manganate(VII). You will then use your results to calculate the concentration of the acidified potassium manganate(VII) solution.
You are provided with:
• Hydratedammoniumiron(II)sulfate,(NH4)2Fe(SO4)2.6H2O • Dilutesulfuricacid • Deionisedwater • A250cm3 volumetric flask • Anacidifiedsolutionofpotassiummanganate(VII)
(a) (i) Weigh out between 8.80 and 8.90 g of ammonium iron(II) sulfate. Record the mass to two decimal places.
Massof(NH4)2Fe(SO4)2.6H2O [2]
(ii)Dissolvetheweighedsampleinapproximately100cm3 of dilute sulfuric acid and make the solution up to 250 cm3 in the volumetric flask using deionised water. Calculate the concentration of the solution in mol dm–3.
[3]
8813.03 R 3 [Turn over
Examiner Only Marks Remark
(b) Titrate 25.0 cm3 portions of your solution with acidified potassium manganate(VII). Record your results in a suitable table in the space below. Calculate the average titre.
[8]
(c) (i) Describehowyouensuredtheendpointofyourtitrationwasaccurate.
[2]
(ii) State the colour change at the end point of your titration.
[1]
8813.03 R 4
Examiner Only Marks Remark
(d) (i) Write the half-equation for the reduction of acidified manganate(VII) ions to form manganese(II) ions.
[2]
(ii) Write the half-equation for the oxidation of iron(II) ions to form iron(III) ions.
[1]
(iii) Write the ionic equation for the reaction.
[2]
(iv) Calculate the concentration of the acidified potassium manganate(VII) solution in g dm–3.
[4]
8813.03 R 5 [Turn over
blANk pAGE(Questions continue overleaf)
8813.03 R 6
Examiner Only Marks Remark
2 Observation/deduction
Safety glasses must be worn at all times and care should be exercised during this practical examination.
(a) (i) You are provided with a solid, labelled X. Carry out the following tests. Record your observations in the spaces below.
Test Observations
1DescribetheappearanceofX.
[1]
2DissolvetwospatulameasuresofXin approximately 50 cm3 of water.
Keep this solution for use in further tests.
[1]
3 Place 4 cm3 of the solution from test 2 in a test tube.
Add an equal volume of concentrated hydrochloric acid.
[1]
4 Place 4 cm3 of the solution from test 2 in a test tube.
Add an equal volume of 1,2-diaminoethane solution. [1]
5 (a) Place 4 cm3 of the solution from test 2 in a test tube. Slowly add an equal volume of sodium hydroxide solution.
(b) Add a further 5 cm3 of sodium hydroxide solution. [2]
6 Place 4 cm3 of the solution from test 2 in a test tube. In a fume cupboard, add an equal volume of concentrated ammonia solution.
[1]
7 Place 4 cm3 of the solution from test 2 in a test tube. Add 1 cm3 of barium chloride solution dropwise.
[1]
(ii) Identify X.
[2]
8813.03 R 7 [Turn over
Examiner Only Marks Remark
(iii) Write the formula of the complex ion formed in test 2.
[1]
(iv) Write the formula of the complex ion formed in test 3.
[1]
(v) Write an ionic equation for the reaction occurring in test 4.
[2]
(vi) Write an ionic equation for the reaction occurring in test 6.
[2]
8813.03 R 8
Examiner Only Marks Remark
(b) (i) You are provided with an aqueous solution of an organic compound Y. Carry out the following tests. Record your observations in the spaces below.
Test Observations
1Describethesolution.Includeadescription of its smell.
[1]
2 Place 4 cm3 of the solution in a test tube. Add an equal volume of potassium dichromate solution and acidify with 1 cm3 of dilute sulfuricacid.Heatinawaterbathfor five minutes. [1]
3 Place 4 cm3 of the solution in a test tube. Add half a spatula measure of sodium hydrogencarbonate. [2]
(ii) Identify the functional group present in Y.
[1]
(iii) Suggest how the infrared spectrum of Y could confirm the presence of this functional group.
[2]
(iv) Suggest how the mass spectrum of Y could confirm its identity.
[2]
8813.03 R 9 [Turn over
blANk pAGE(Questions continue overleaf)
8813.03 R 10
Examiner Only Marks Remark
3 planning exercise
Ethyl 3-nitrobenzoate exists as a solid at room temperature and pressure. Its melting point is 42 °C.
COOC2H5
NO2
(a) (i) Write the equation for the formation of ethyl 3-nitrobenzoate from ethyl benzoate.
[1]
(ii) Assuming a 60% yield, calculate the minimum mass of the organic reactant required to produce 5.85 g of ethyl 3-nitrobenzoate.
[2]
(b) Describethelaboratorypreparationofethyl3-nitrobenzoateupto and including the removal of the crude product from the reaction mixture.
[5]
Quality of written communication [2]
8813.03 R 11 [Turn over
Examiner Only Marks Remark
(c) (i) The crude product is recrystallised before its melting point is determined. Explain why recrystallisation is carried out and, giving experimental details, describe the process of recrystallisation.
[4]
(ii) Howwouldthecrystalsbedriedbeforethemeltingpointisdetermined?
[1]
(iii) Howwouldyouusethemeltingpointtodeterminewhetherthecrystals are pure ethyl 3-nitrobenzoate?
[2]
8813.03 R 12
Examiner Only Marks Remark
(d) Part of the nmr spectrum for ethyl 3-nitrobenzoate is shown below. The aromatic protons are shown. Complete the nmr spectrum in terms of integration and splitting pattern.
1 02345
ppm
6789
THIS IS THE END OF THE QUESTION pApER
[3]
8813.03 R
Permission to reproduce all copyright material has been applied for.In some cases, efforts to contact copyright holders may have been unsuccessful and CCEAwill be happy to rectify any omissions of acknowledgement in future if notified.
ADVANCEDGeneral Certificate of Education
2014
Chemistry
Assessment Unit A2 3Internal Assessment
Practical Examination 2 [AC232]
FRIDAY 16 MAY
8812.05 R
APPARATUSAND
MATERIALSLIST
*AC232*
AC
232
Updated version for Practical Examination 2
8812.05 R 22 [Turn over
Advice for centres
● All chemicals used should be at least laboratory reagent specification and labelled with appropriate safety symbols, e.g. irritant.
● For centres running multiple sessions – candidates for the later session should be supplied with clean, dry glassware. If it is not feasible then glassware from the first session should be thoroughly washed, rinsed with deionised water and allowed to drain.
● Ensure all chemicals are in date otherwise expected observations may not be seen.
8812.05 R 3 3
Practical Examination 2
Each candidate must be supplied with safety goggles or glasses.
Question 1
Each candidate must be supplied with:
• one 50 cm3 burette of at least class B quality
• one 25 cm3 pipette of at least class B quality
• one 250 cm3 volumetric fl ask
• a safety pipette fi ller
• three conical fl asks of 250 cm3 capacity
• a funnel for fi lling the burette (optional)
• a white tile or white paper
• one beaker of 250 cm3 capacity
• a wash bottle containing deionised/distilled water
• a retort stand and clamp
• weighing bottle (or equivalent)
• approximately 9.0 g of ammonium iron(II) sulfate labelled as ammonium iron(II) sulfate and HARMFUL
• access to an accurate balance (reading to 2 decimal places)
• glass rod
• spatula
• 250 cm3 of dilute sulfuric acid (approximately 1.0 mol dm–3) labelled dilute sulfuric acid and CAUTION and IRRITANT
• 150 cm3 of 0.02 mol dm–3 acidifi ed potassium manganate(VII) labelled potassium manganate(VII) solution and HARMFUL.
8812.05 R 44 [Turn over
Practical Examination 2
Question 2
Each candidate must be supplied with:
• a small beaker
• fi ve test tubes
• a boiling tube
• a test tube holder
• a test tube rack
• a spatula
• a stirring rod
• a heat-proof mat
• a Bunsen burner
• several plastic droppers
• deionised water
• kettle to supply hot water (optional)
• hydrated copper(II) sulfate (approximately 3.0 g) labelled X and HARMFUL
• about 10 cm3 of concentrated hydrochloric acid in a stoppered reagent bottle labelled concentrated hydrochloric acid and CORROSIVE
• about 10 cm3 of an aqueous solution of 1,2-diaminoethane (approximately 0.2M) labelled 1,2-diaminoethane and IRRITANT
• about 10 cm3 of an aqueous solution of sodium hydroxide (approximately 2.0M) labelled sodium hydroxide and CORROSIVE
• a reagent bottle containing concentrated ammonia labelled concentrated ammonia and CORROSIVE (available in the fume cupboard(s)). Each candidate will only need about 10 cm3
• about 10 cm3 of aqueous solution of barium chloride (approximately 0.1M) labelled barium chloride solution and HARMFUL
• about 10 cm3 of aqueous ethanoic acid (approximately 25% glacial 75% water) labelled Y and IRRITANT
• about 10 cm3 of aqueous potassium dichromate (approximately 0.1M) labelled potassium dichromate and TOXIC
• 2M sulfuric acid labelled dilute sulfuric acid and CORROSIVE
• 2–3 g of sodium hydrogencarbonate labelled sodium hydrogencarbonate.
8812.05 R 5 5
8812.05 R 66 [Turn over
8812.05 R 88 [Turn over
8812.03 [Turn over
ADVANCEDGeneral Certificate of Education
2014
Chemistry
Assessment Unit A2 3Internal Assessment
Practical Examinations 1 and 2
[AC231] [AC232]
THURSDAY 15 AND FRIDAY 16 MAY
Confidential Instructionsto the Supervisor
of the Practical Examination
8812.03 [Turn over
INSTRUCTIONS TO THE SUPERVISOR OF THE PRACTICAL EXAMINATION
General
1. The instructions contained in this document are for the use of the Supervisor and are strictly confidential. Under no circumstances may information concerning apparatus or materials be given before the examination to a candidate or other unauthorised person.
2. In a centre with a large number of candidates it may be necessary for two or more examination sessions to be organised. It is the responsibility of the schools to ensure
that there should be no contact between candidates taking each session.
3. A suitable laboratory must be reserved for the examination and kept locked throughout the period of preparation. Unauthorised persons not involved in the preparation for the examination must not be allowed to enter. Candidates must not be admitted until the specified time for commencement of the examination.
4. The Supervisor must ensure that the solutions provided for the candidates are of the nature and concentrations specified in the Apparatus and Materials List.
5. The Supervisor is to be granted access to the Teacher’s Copy of the Question Paper, showing parts of questions 1 and 2 only, on Monday 12 May 2014. The Supervisor is asked to check, at the earliest opportunity, that the experiments and tests in the question paper may be completed satisfactorily using the apparatus, materials and solutions that have been assembled. This question paper must then be returned to safe custody at the earliest possible moment after the Supervisor has ensured that all is in order. No access to the question paper should be allowed before 12 May 2014.
6. In the case of centres who have candidates entered for both practical examinations, the Supervisor must return all unused scripts of Practical Examination 1 to the Examinations Officer immediately on completion of the examination. The contents of
this examination must be kept confidential until the completion of Practical Examination 2.
7. Pipettes and burettes should be checked before the examination, and there should be an adequate supply of spare apparatus in case of breakages. The Apparatus and Materials List should be regarded as a minimum and there should be no objection to candidates being supplied with more than the minimum amount of apparatus and materials.
8. Candidates may not use text books and laboratory notes for reference during the examination, and must be informed of this beforehand.
8812.03 [Turn over
9. Clear instructions must be given by the Supervisor to all candidates at the beginning of the examination concerning appropriate safety procedures and precautions. Supervisors are also advised to remind candidates that all substances in the examination must be treated with caution. Only those tests specified in the question paper should be attempted. Candidates must not attempt any additional confirmatory tests. Anything
spilled on the skin should be washed off immediately with plenty of water. The use of appropriate eye protection is essential.
10. Supervisors are reminded that they may not assist candidates during the examination. However, if in the opinion of the Supervisor, a candidate is about to do something which may endanger him/herself or others, the Supervisor should intervene. A full written report must be sent to CCEA at once.
11. Upon request, a candidate may be given additional quantities of materials (answer paper, reagents and unknowns) without penalty. No notification need be sent to CCEA.
12. The examination room must be cleared of candidates immediately after the examination.
13. No materials will be supplied by CCEA.
8812.03 [Turn over
Northern Ireland Council for the Curriculum, Examinations andAssessment
General Certificate of Education
Advanced
Chemistry
Practical Examination 1
Thursday 15 May 2014
This report must be completed by the Supervisor during the examination.The complete report should include all candidates taking this PracticalExamination. This Supervisor’s Report should be copied and attached toEach Advice Note bundle and returned to CCEA in the normal way.
Comments:
Supervisor’s Signature . . . . . . . . . . . . . . . . . . . Date . . . . . . . . . . .
71
Centre Number
Candidate Number
8812.03 [Turn over
Northern Ireland Council for the Curriculum, Examinations andAssessment
General Certificate of Education
Advanced
Chemistry
Practical Examination 2
Friday 16 May 2014
This report must be completed by the Supervisor during the examination.The complete report should include all candidates taking this PracticalExamination. This Supervisor’s Report should be copied and attached toEach Advice Note bundle and returned to CCEA in the normal way.
Comments:
Supervisor’s Signature . . . . . . . . . . . . . . . . . . . Date . . . . . . . . . . .
71
Centre Number
Candidate Number
8812.03
ADVANCEDGeneral Certificate of Education
2014
8813.01F
MARKSCHEME
ChemistryAssessment Unit A2 3
Internal AssessmentPractical Examination 2
[AC232]
FRIDAY 16 MAY, MORNING
8813.01F 22 [Turn over
AVAILABLEMARKS
Annotation
1. Please do all marking in red ink.
2. All scripts should be checked for mathematical errors. Please adopt a system of one tick () equals 1 mark, e.g. if you have awarded 4 marks for part of a question then 4 ticks () should be on this candidate’s answer.
3. The total mark for each question should be recorded in a circle placed opposite the question number in the teacher mark column.
4. As candidates have access to scripts please do not write any inappropriate comments on their scripts.
General points
• All calculations are marked according to the number of errors made.
• Errors can be carried through. If the wrong calculation is carried out then the incorrect answer can be carried through. One mistake at the start of a question does not always mean that all marks are lost.
• Any number of decimal places may be used provided the ‘rounding’ is correct.
• Listing is when more than one answer is given for a question that only requires one answer, e.g. the precipitate from a chloride with silver nitrate is a white solid; if the candidate states a white or a cream solid, one answer is correct and one answer is wrong. Hence they cancel out.
• Although names might be in the mark scheme it is generally accepted that formulae can replace them. Formulae and names are often interchangeable in chemistry.
• The marking of colours is defined in the ‘CCEA GCE Chemistry Acceptable Colours’ document.
MARKING GUIDELINES
Interpretation of the Mark Scheme
• Carry error through This is where mistakes/wrong answers are penalised when made, but if carried
into further steps of the question, then no further penalty is applied. This pertains to calculations and observational/deduction exercises. Please annotate candidates’ answers by writing the letters c.e.t. on the appropriate place in the candidates’ answers.
• Oblique/forward slash This indicates an acceptable alternative answer(s).
• Brackets Where an answer is given in the mark scheme and is followed by a word/words in
brackets, this indicates that the information within the brackets is non-essential for awarding the mark(s).
8813.01F 3 3
AVAILABLEMARKS
1 (a) (i) Mass between given values Mass to 2 decimal places Units Error [–1] [2]
(ii) Correct RFM for ammonium iron(II) sulfate (392) Correct calculation of moles Correct calculation of concentration Error [–1] [3] (b) Table [3] Significant figures [2] Calculation of average titre [2] Titration consistency [1] [8]
Table
Titration Initial burettereading/cm3
Final burette reading/cm3
Volumeadded/cm3
1
2
3 Average titre = cm3
Table [3] The Table should be drawn as a table. It should be labelled with the following: initial burette reading, final burette reading and the titre. It is not necessary to use exactly these words but there should be appropriate
columns and rows [1]. Units, i.e. cm3, should be stated [1]. The rough titration value should not be the same as the accurate values [1].
Significant figures [2] All accurate titration readings recorded to one decimal place (including initial burette reading at 0.0 if used). Accept, however, 0.00 and 0.05 but penalise by [–1] if other readings are given to two or more decimal places. The use of 0 is penalised by [–1] if used (only penalise once). Average titre [2] Accurate titrations only should be used. The use of a rough value is [–1].
The average value can be calculated to two decimal places or more, e.g. 25.17 and 25.18 average to 25.175.
If three accurate titres are recorded, then the average titre must be calculated using all three accurate titres.
Any error is [–1]. This might be an incorrect calculation or the omission of units. If the average titre is included in the table then the units indicated on the table apply.
Titration consistency
Difference Mark ±0.1 [1] >0.1 [0]
8813.01F 44 [Turn over
AVAILABLEMARKS
(c) (i) add solution from burette slowly/dropwise at end point [1] swirl the flask/wash down the sides with deionised water etc. [1] [2]
(ii) colourless to pink [1]
(d) (i) MnO4– + 8H+ + 5e– → Mn2+ + 4H2O [2]
(ii) Fe2+ → Fe3+ + e– [1]
(iii) 5Fe2+ + 8H+ + MnO4– → 5Fe3+ + 4H2O + Mn2+ [2]
(iv) for a concentration of 0.09 mol dm–3 Fe2+ and a titration value of 20.1 cm3
25/1000 × 0.09 mol in 25 cm3 of Fe2+ solution = 2.25 × 10–3 mol
2.25 × 10–3/5 mol KMnO4 in 20.1 cm3 = 4.5 × 10–4 mol in 20.1 cm3
KMnO4 = 158; 4.5 × 10–4 mol = 158 × 4.5 × 10–4 g = 0.0711 g
0.0711 g in 20.1 cm3 = 0.0711/20.1 × 103 = 3.537 g = 3.54 g [4] 25
8813.01F 5 5
AVAILABLEMARKS
2 Observation/deduction
Safety glasses must be worn at all times and care should be exercised during this practical examination.
(a) (i) You are provided with a solid, labelled X. Carry out the following tests. Record your observations in the spaces below.
Test Observations
1 Describe the appearance of X. Blue solid/crystals/powder[1]
2 Dissolve two spatula measures of X in approximately 50 cm3 of water.
Keep this solution for use in further tests.Blue (solution)
[1]
3 Place 4 cm3 of the solution from test 2 in a test tube. Add an equal volume of concentrated hydrochloric acid. Yellow-green/Green solution
[1]4 Place 4 cm3 of the solution from test 2
in a test tube. Add an equal volume of 1,2-diaminoethane solution. Darker blue solution/
blue-violet/blue-purple[1]
5 (a) Place 4 cm3 of the solution from test 2 in a test tube. Slowly add an equal volume of sodium hydroxide solution.
(b) Add a further 5 cm3 of sodium hydroxide solution.
Blue precipitate
Precipitate remains[2]
6 Place 4 cm3 of the solution from test 2 in a test tube. In a fume cupboard, add an equal volume of concentrated ammonia solution.
Deep blue solution forms[1]
7 Place 4 cm3 of the solution from test 2 in a test tube. Add 1 cm3 of barium chloride solution dropwise. White precipitate
[1]
(ii) hydrated [1] copper(II) sulfate [1] [2]
(iii) [Cu(H2O)6]2+ [1]
(iv) [CuCl4]2– [1]
(v) [Cu(H2O)6]2+ + 3 en [Cu(en)3]2+ + 6 H2O [2]
(vi) [Cu(H2O)6]2+ + 4 NH3 [Cu(NH3)4 (H2O)2]2+ + 4 H2O [2]
8813.01F 66 [Turn over
AVAILABLEMARKS
(b) (i) You are provided with an aqueous solution of an organic compound B. Carry out the following tests. Record your observations in the spaces below.
Test Observations
1 Describe the solution. Include a description of its smell.
ColourlessVinegar smell/sharp/irritating
[1]
2 Place 4 cm3 of the solution in a test tube. Add an equal volume of potassium dichromate solution and acidify with 1 cm3 of dilute sulfuric acid. Heat in a water bath for five minutes.
Solution remains orange [1]
3 Place 4 cm3 of the solution in a test tube. Add half a spatula measure of sodium hydrogencarbonate.
Solid dissolvesbubbles/effervescence/fizzing
[2]
(ii) –COOH [1]
(iii) strong C O absorption [1] strong O H absorption [1] [2]
(iv) position of molecular ion gives RMM [1] uniqueness of fragmentation [1] [2] 25
8813.01F 7 7
AVAILABLEMARKS
3 Planning Exercise
(a) (i) C6H5COOC2H5 + HNO3 → C6H4NO2COOC2H5 + H2O [1] (ii) Theoretical yield = 9.75 g or 0.05 mole [1] Min mass of ethyl benzoate 7.5 g [1] [2]
(b) Place concentrated sulfuric and concentrated nitric acid in a flask [1] Add slowly to ethyl benzoate [1] temperature kept below 15 °C [1] pour reaction mixture onto crushed ice [1] filter [1] [5]
Quality of written communication [2] (c) (i) To remove impurities [1] dissolve in minimum amount of hot ethanol/methanol [1] filter while hot allow (filtrate) to cool/crystals to form [1] vacuum filtration for crystals [1] [4]
(ii) between filter papers/cool oven/desiccator [1]
(iii) sharp m. pt [1] compare to 42°C [1] [2] (d)
quartet and triplet [1] triplet closer to TMS [1] integration (2:3) [1] [3] 20 Total 70
1 02345
ppm
6789
TIME1 hour 15 minutes.
INSTRUCTIONS TO CANDIDATESWrite your Centre Number and Candidate Number in the spaces provided at the top of this page.Answer both questions.Write your answers in the spaces provided.
INFORMATION FOR CANDIDATESThe total mark for this paper is 20.Question 1 is a practical exercise worth 8 marks.Question 2 is a practical exercise worth 12 marks.Figures in brackets printed down the right-hand side of pages indicate the marks awarded to each question or part question.A Periodic Table of Elements (including some data) is provided.You may not have access to notes, textbooks and other material to assist you.
9568
Question Number
Marks
Examiner Mark Remark
12
TotalMarks
Centre Number
Candidate Number
Chemistry
Assessment Unit A2 3assessing
Module 3: Practical ExaminationPractical Booklet A
[AC233]TUESDAY 5 MAY, MORNING
ADVANCEDGeneral Certificate of Education
2015
*AC233*
AC
233
BLANK PAGE
9568 2
9568 3 [Turn over
Examiner Mark Remark
Practical Booklet A
Safety glasses must be worn at all times and care should be exercised during the practical examination.
1 Titration exercise
You are required to titrate standard sodium thiosulfate solution against iodine liberated by the reaction of a solution of potassium iodate(V) with acidified potassium iodide solution.
You are provided with the following: a solution of potassium iodate(V) four 20 cm3 portions of sulfuric acid potassium iodide solution sodium thiosulfate solution of concentration 0.10 mol dm−3
starch indicator
1. Rinse and fill the burette with the appropriate solution. 2. Use a measuring cylinder to pour 10 cm3 of potassium iodide solution
into a 250 cm3 conical flask. 3. Add 20 cm3 of dilute sulfuric acid to the solution in the conical flask. 4. Use a measuring cylinder to add 5 cm3 of potassium iodate(V) solution
to the acidified potassium iodide solution. 5. Titrate 0.10 mol dm−3 sodium thiosulfate solution against the iodine
formed.
Present your results in a suitable table and calculate the average titre.
Results table
[8]
Examiner Mark Remark
9568 4
2 Observation exercise
(a) You are provided with a salt, labelled X. Carry out the following tests on X and record your observations in the table below.
Test Observations
1 Describe the appearance of X. [1]
2 Add 3 spatula measures of X to 20 cm3 of water and stir until there is no further change. Use this solution for tests 3, 4 and 5. [1]
3 (a) In a fume cupboard add 5 drops of concentrated ammonia solution to 2 cm3 of the solution of X in a test tube.
(b) Add a further 5 cm3 of concentrated ammonia solution to the test tube. [2]
4 (a) Add 5 drops of sodium hydroxide solution to 2 cm3 of the solution of X in a test tube.
(b) Add a further 5 cm3 of sodium hydroxide solution to the test tube. [2]
5 Add 2 cm3 of barium chloride solution to a test tube containing 2 cm3 of the solution of X. [1]
6 Place a half spatula measure of X onto a watch glass in a fume cupboard. Wearing gloves, slowly add 10 drops of concentrated sulfuric acid to X. [1]
7 Place a spatula measure of X in a dry boiling tube. Heat the boiling tube gently.
[2]
Examiner Mark Remark
9568 5
(b) You are provided with an organic liquid labelled Y. Carry out the following tests and record your observations in the table below.
N.B. Water bath filled using hot water from a kettle.
Test Observations1 Add 10 drops of Y to 2 cm3 of
acidified potassium dichromate solution in a test tube. Place the test tube in a hot water bath for 5 minutes. [1]
2 Add 1 cm3 of Y to 2 cm3 of Fehling’s solution in a test tube. Place the test tube in a hot water bath for 5 minutes. [1]
THIS IS THE END OF THE QUESTION PAPER
200372
Permission to reproduce all copyright material has been applied for.In some cases, efforts to contact copyright holders may have been unsuccessful and CCEAwill be happy to rectify any omissions of acknowledgement in future if notified.
ADVANCEDGeneral Certificate of Education
2015
Chemistry
Assessment Unit A2 3assessing
Module 3: Practical ExaminationPractical Booklet A
[AC233]
TUESDAY 5 MAY, MORNING
9568.02
APPARATUSAND
MATERIALSLIST
*AC233*
AC
233
9568.02 22 [Turn over
Advice for centres
• All chemicals used should be at least laboratory reagent specification and labelled with appropriate safety symbols, e.g. irritant.
• For centres running multiple sessions – candidates for the later session should be supplied with clean, dry glassware. If it is not feasible then glassware from the first session should be thoroughly washed, rinsed with deionised water and allowed to drain.
• Ensure all chemicals are in date otherwise expected observations may not be seen.
9568.02 3 3
Practical Examination
Each candidate must be supplied with safety goggles or glasses.
Question 1
Each candidate must be supplied with:
• one 50 cm3 burette of at least class B quality;
• a funnel for filling the burette;
• a retort stand and clamp;
• a beaker of 100 cm3 capacity;
• two 10 cm3 measuring cylinders;
• a plastic dropper;
• three conical flasks of 250 cm3 capacity;
• a white tile or white paper;
• a wash bottle containing deionised water;
• 150 cm3 of 0.10 mol dm–3 sodium thiosulfate solution labelled sodium thiosulfate solution 0.10 mol dm–3;
• sulfuric acid 4 × 20 cm3 portions of approximately 2 mol dm–3 sulfuric acid solution labelled sulfuric acid, corrosive and irritant;
• 4 × 10 cm3 portions of 1M potassium iodide solution, labelled potassium iodide solution;
• 150 cm3 of approximately 0.10 mol dm–3 potassium iodate(V) solution labelled potassium iodate(V) solution and oxidising;
• starch indicator 2% (w/v) with dropper. Add 2 g of starch to a small amount of water, make into a paste. Make up to 100 cm3 in boiling water. Labelled starch indicator.
Appropriate amounts should be prepared for the total number of candidates taking theexamination.
9568.02 44 [Turn over
Question 2
Candidates should have access to a fume cupboard.
Each candidate must be supplied with:
• small beaker (100 cm3);
• six test tubes;
• one boiling tube;
• a test tube rack;
• a spatula;
• a heatproof mat;
• a Bunsen burner;
• several plastic droppers;
• one 250 cm3 beaker;
• one pair of gloves;
• tongs;
• a watch glass;
• about 3.0 g of hydrated iron(II) sulfate, labelled X;
• about 10 cm3 of barium chloride solution in a reagent bottle/beaker labelled barium chloride solution. This solution should be approximately 0.1 M (20.8 g/dm3 for BaCl2 or 24.4 g/dm3 for BaCl2.2H2O);
• about 10 cm3 of sodium hydroxide solution in a reagent bottle/beaker labelled sodium hydroxide solution and corrosive. This solution should be approximately 2 mol dm–3;
• a reagent bottle containing concentrated ammonia solution labelled concentrated ammonia solution and irritant (Placed in fume cupboard);
• a reagent bottle containing concentrated sulfuric acid labelled concentrated sulfuric acid and corrosive (Placed in fume cupboard);
• about 10 cm3 of ethanal in a stoppered container labelled Y, flammable and harmful;
• 10 cm3 of Fehling’s solution (a mix of equal volumes of Fehling’s No 1 and Fehlings No 2) labelled Fehling’s solution and corrosive;
• about 5 cm3 of potassium dichromate(VI) solution in a stoppered reagent bottle labelled acidified potassium dichromate solution and irritant. This solution should be about 0.1 mol dm–3, made by dissolving 30 g of potassium dichromate(VI) in 100 cm3 of
1 mol dm–3 sulfuric acid and made up to 1 dm3 with deionised water;
• access to a kettle.
9568.02 5 5
Risk Assessment
The risk assessment below applies both to the preparation of the materials for the practical examination as well as the conducting of the examination.
Care should be taken when handling glassware, and breakages should be removed immediately and disposed of safely.
Candidates should only conduct the tasks as described in the practical exam.
Under no circumstances should ethanal be heated with a naked flame; a water bath must be used. If hot water is obtained from a kettle, the kettle should be PAT tested and be labelled as such.
Question 1
Sodium thiosulfate is low hazard, if contact is made with eyes or mouth wash with water.EMERGENCY ACTION
• In the eye. Flood the eye with gently-running tap water for 10 minutes. See a doctor if pain persists.
• Swallowed. Do no more than wash out the mouth with water. Do not induce vomiting. Sips of water may help cool the throat and help keep the airway open. See a doctor.
• Spilt on the skin or clothing. Brush solid off contaminated clothing. Rinse clothing or the skin as necessary.
• Spilt on the floor, bench, etc. Brush up solid spills, trying to avoid raising dust, then wipe with a damp cloth. Wipe up solution spills with a cloth and rinse it well.
Sulfuric acid (2.0 M) is corrosive and can cause severe burns, care should be taken to avoid contact with skin and eyes. If handling larger quantities gloves should be worn.EMERGENCY ACTION
• In the eye. Flood the eye with gently-running tap water for 10 minutes. See a doctor.
• Swallowed. Do no more than wash out the mouth with water. Do not induce vomiting. Sips of water may help cool the throat and help keep the airway open. See a doctor.
• Spilt on the skin or clothing. Remove contaminated clothing. Especially with concentrated acid, quickly use a dry cloth or paper towel to wipe as much liquid as possible off the skin. Then drench the skin with plenty of water. If a large area is affected or blistering occurs, see a doctor.
• Spilt on the floor, bench etc. Wipe up small amounts with a damp cloth and rinse it well. For larger amounts and especially for (moderately) concentrated acid, cover with mineral absorbent (e.g. cat litter) and scoop into a bucket. Neutralise with sodium carbonate. Rinse with plenty of water.
9568.02 66 [Turn over
Potassium iodide is low hazard, if contact is made with eyes or mouth wash with water.EMERGENCY ACTION
• In the eye. Flood the eye with gently-running tap water for 10 minutes. See a doctor if pain persists.
• Swallowed. Do no more than wash out the mouth with water. Do not induce vomiting. Sips of water may help cool the throat and help keep the airway open. See a doctor.
• Spilt on the skin or clothing. Brush solid off contaminated clothing. Rinse clothing or the skin as necessary.
• Spilt on the floor, bench etc. Brush up solid spills, trying to avoid raising dust, then wipe with a damp cloth. Wipe up solution spills with a cloth and rinse it well.
Potassium iodate is an oxidising agent and may also cause irritation to the skin and eyes, care should be taken to avoid contact with the skin.EMERGENCY ACTION
• In the eye. Flood the eye with gently-running tap water for 10 minutes. See a doctor if pain persists.
• Swallowed. Do no more than wash out the mouth with water. Do not induce vomiting. Sips of water may help cool the throat and help keep the airway open. See a doctor.
• Spilt on the skin or clothing. Brush solid off contaminated clothing. Rinse clothing or the skin as necessary.
• Spilt on the floor, bench, etc. Brush up solid spills, trying to avoid raising dust, then wipe with a damp cloth. Wipe up solution spills with a cloth and rinse it well.
• Disposal. 50 g should be dissolved in 1 litre of water before pouring down a drain.
Starch solution may be an irritant to the skin and eyes.If contact is made with skin or eyes it should be flushed with copious amounts of water and medical advice sought if necessary.
9568.02 7
Question 2
Iron sulfate is harmful if swallowed.EMERGENCY ACTION
• In the eye. Flood the eye with gently-running tap water for at least 10 minutes. See a doctor.
• Swallowed. Do no more than wash out the mouth with water. Do not induce vomiting. Sips of water may help cool the throat and help keep the airway open. See a doctor.
• Dust breathed in. Remove the casualty to fresh air. See a doctor if breathing is difficult.
• Spilt on the skin or clothing. Remove contaminated clothing and rinse it. Wash off the skin with plenty of water.
• Spilt on the floor, bench, etc. Scoop up solid (take care not to raise dust). Wipe up small solution spills or any traces of solid with cloth. For larger spills use mineral absorbent (e.g. cat litter).
• Disposal. Dilute to below 0.2 M and pour down a drain.
Barium chloride is toxic if swallowed, harmful by inhalation and irritating to the eyes, skin and lungs. Wash hands after handling barium compounds.EMERGENCY ACTION
• In the eye. Flood the eye with gently-running tap water for at least 20 minutes. See a doctor. If a visit to hospital is necessary, continue washing the eye during the journey in an ambulance.
• Swallowed. Do no more than wash out the mouth with water. Do not induce vomiting. Sips of water may help cool the throat and help keep the airway open. See a doctor.
• Spilt on the skin or clothing. Remove contaminated clothing. Drench the skin with plenty of water. If a large area is affected or blistering occurs, see a doctor.
• Spilt on the floor, bench, etc. Wipe up small amounts with a damp cloth and rinse it well. For larger amounts, and especially for (moderately) concentrated solutions, cover with mineral absorbent (e.g. cat litter) and scoop into a bucket. Rinse with plenty of water.
• Disposal. Dilute to below 0.05 M and pour down a drain.
Sodium hydroxide. It causes severe burns; it is particularly dangerous to the eyes. Small amounts should be used. Gloves should be worn if larger amounts are used.EMERGENCY ACTION
• In the eye. Flood the eye with gently-running tap water for at least 20 minutes. See a doctor. If a visit to hospital is necessary, continue washing the eye during the journey in an ambulance.
• Swallowed. Do no more than wash out the mouth with water. Do not induce vomiting. Sips of water may help cool the throat and help keep the airway open. See a doctor.
• Spilt on the skin or clothing. Remove contaminated clothing. Drench the skin with plenty of water. If a large area is affected or blistering occurs, see a doctor.
• Spilt on the floor, bench, etc. Wipe up small amounts with a damp cloth and rinse it well. For larger amounts and especially for (moderately) concentrated solutions, cover with mineral absorbent (e.g. cat litter) and scoop into a bucket. Neutralise with citric acid. Rinse with plenty of water.
Ammonia solution is corrosive and causes burns and is dangerous to the eyes, goggles should be worn, and ammonia causes severe internal damage if swallowed.EMERGENCY ACTION
• In the eye. Flood the eye with gently-running tap water for at least 20 minutes (for alkalis). See a doctor. If it is necessary to go to hospital continue washing the eye during the journey in an ambulance.
• Vapour breathed in. Remove the casualty to fresh air. Call a doctor if breathing is difficult.
• Swallowed. Do no more than wash out the mouth with water. Do not induce vomiting. Sips of water may help cool the throat and help keep the airway open. See a doctor.
• Spilt on the skin or clothing. Remove contaminated clothing. Drench the skin with plenty of water. If a large area is affected or blistering occurs, see a doctor.
• Spilt on the floor, bench etc. Consider the need to evacuate the laboratory and open windows if large amounts
are spilt and especially for (moderately) concentrated solutions. Cover with mineral absorbent (e.g. cat litter) and scoop into a bucket. Neutralise with citric acid. Rinse with plenty of water. Wipe up small amounts with a damp cloth and rinse it well.
9568.02 8
9568.02 9 9
Sulfuric acid is corrosive, causing severe burns and reacts violently with water. Ifhandling larger amounts, gloves could be worn.EMERGENCY ACTION
• In the eye. Flood the eye with gently-running tap water for 10 minutes. See a doctor.
• Swallowed. Do no more than wash out the mouth with water. Do not induce vomiting. Sips of water may help cool the throat and help keep the airway open. See a doctor.
• Spilt on the skin or clothing. Remove contaminated clothing. Especially with concentrated acid, quickly use a dry cloth or paper towel to wipe as much liquid as possible off the skin. Then drench the skin with plenty of water. If a large area is affected or blistering occurs, see a doctor.
• Spilt on the floor, bench, etc. Wipe up small amounts with a damp cloth and rinse it well. For larger amounts, and especially for (moderately) concentrated acid, cover with mineral absorbent (e.g. cat litter) and scoop into a bucket. Neutralise with sodium carbonate. Rinse with plenty of water.
Ethanal is extremely flammable and can be irritating to the eyes and respiratory system. Ethanal may boil spontaneously and should be cooled before use.EMERGENCY ACTION
• In the eye. Immediately rinse the eye with gently-running water for 10 minutes. See a doctor.
• Vapour breathed in. Remove the casualty to fresh air. Keep him/her warm. See a doctor if breathing is difficult.
• Swallowed. Do no more than wash out the mouth with water. Do not induce vomiting. Sips of water may help cool the throat and help keep the airway open. See a doctor.
• Spilt on the skin or clothing. Remove contaminated clothing. Wash the affected area and clothing with plenty of water.
• Spilt on the floor, bench etc. Put out all Bunsen burner flames. Wipe up small amounts with a cloth and rinse it well. For larger amounts, open all windows, cover with mineral absorbent (e.g. cat litter), and scoop into a bucket and add water.
Fehling’s solution contains concentrated sodium hydroxide solution (see entry for sodium hydroxide above) as well as copper(II) sulfate which is low hazard.EMERGENCY ACTION (see sodium hydroxide above)
9568.02 1010 [Turn over
Potassium dichromate is toxic by inhalation and if swallowed may cause ulcers. Potassium dichromate is also oxidising and may be carcinogenic by inhalation, however inhalation is unlikely in school use.
EMERGENCY ACTION
• In the eye. Flood the eye with gently-running tap water for at least 10 minutes See a doctor.
• Swallowed. Do no more than wash out the mouth with water. Do not induce vomiting. Sips of water may help cool the throat and help keep the airway open. See a doctor.
• Spilt on the skin or clothing. Remove contaminated clothing and rinse it until no colour remains. Wash off the skin with plenty of water. If skin contamination is more than small, see a doctor.
• Spilt on the floor, bench, etc. Wear eye protection and gloves. Scoop up the solid. Rinse the area with water and wipe up, rinsing repeatedly until no colour remains. Rinse the mop or cloth thoroughly.
9568.02 [Turn over
9568.06 [Turn over
ADVANCEDGeneral Certificate of Education
2015
Chemistry
Assessment Unit A2 3Practical Assessment
Practical Booklet A
[AC233]
TUESDAY 5 MAY
Confidential Instructionsto the Supervisor
of the Practical Examination
9568.06 [Turn over
INSTRUCTIONS TO THE SUPERVISOR OF THE PRACTICAL EXAMINATION
General
1. The instructions contained in this document are for the use of the Supervisor and are strictly confidential. Under no circumstances may information concerning apparatus or materials be given before the examination to a candidate or other unauthorised person.
2. In a centre with a large number of candidates it may be necessary for two or more examination sessions to be organised. It is the responsibility of the schools to ensure
that there should be no contact between candidates taking each session.
3. A suitable laboratory must be reserved for the examination and kept locked throughout the period of preparation. Unauthorised persons not involved in the preparation for the examination must not be allowed to enter. Candidates must not be admitted until the specified time for commencement of the examination.
4. The Supervisor must ensure that the solutions provided for the candidates are of the nature and concentrations specified in the Apparatus and Materials List.
5. The Supervisor is to be granted access to the Teacher’s Copy of Practical Booklet A on Wednesday 29 April 2015. The Supervisor is asked to check, at the earliest
opportunity, that the experiments and tests in the question paper may be completed satisfactorily using the apparatus, materials and solutions that have been assembled. This question paper must then be returned to safe custody at the earliest possible moment after the Supervisor has ensured that all is in order. No access to the question paper should be allowed before 29 April 2015.
6. Centres may need to carry out multiple sessions to accommodate all their candidates sitting Practical Booklet A in a laboratory. Supervision must take place from 30 minutes after the scheduled starting time of the examination, as set out in the timetable, until the time when the candidate(s) begin(s) their examination(s). This is in order to ensure that there is no contact with other candidates. The centre must appoint a member of staff from the centre to supervise the candidate at all times while he/she is on the premises.
7. Pipettes and burettes should be checked before the examination, and there should be an adequate supply of spare apparatus in case of breakages. The Apparatus and Materials List should be regarded as a minimum and there should be no objection to candidates being supplied with more than the minimum amount of apparatus and materials.
8. Candidates may not use text books and laboratory notes for reference during the examination, and must be informed of this beforehand.
9568.06 [Turn over
9. Clear instructions must be given by the Supervisor to all candidates at the beginning of the examination concerning appropriate safety procedures and precautions. Supervisors are also advised to remind candidates that all substances in the examination must be treated with caution. Only those tests specified in the question paper should be attempted. Candidates must not attempt any additional confirmatory tests. Anything
spilled on the skin should be washed off immediately with plenty of water. The use of appropriate eye protection is essential.
10. Supervisors are reminded that they may not assist candidates during the examination. However, if in the opinion of the Supervisor, a candidate is about to do something which may endanger him/herself or others, the Supervisor should intervene. A full written report must be sent to CCEA at once.
11. Upon request, a candidate may be given additional quantities of materials (answer paper, reagents and unknowns) without penalty. No notification need be sent to CCEA.
12. The examination room must be cleared of candidates immediately after the examination.
13. No materials will be supplied by CCEA.
9568.06 [Turn over
Northern Ireland Council for the Curriculum, Examinations andAssessment
General Certificate of Education
Advanced
Chemistry
Practical Booklet A
Tuesday 5 May 2015
This report must be completed by the Supervisor during the examination.The complete report should include all candidates taking this PracticalExamination. This Supervisor’s Report should be copied and attached toEach Advice Note bundle and returned to CCEA in the normal way.
Comments:
Supervisor’s Signature . . . . . . . . . . . . . . . . . . . Date . . . . . . . . . . .
71
Centre Number
Candidate Number
9568.06 [Turn over
9568.01 F
ChemistryAssessment Unit A2 3
assessing
Module 3: Practical ExaminationPractical Booklet A
[AC233]
TUESDAY 5 MAY, MORNING
MARKSCHEME
ADVANCEDGeneral Certificate of Education
2015
9568.01 F 2 [Turn over
AVAILABLEMARKS
Annotation
1. Please do all marking in red ink.
2. All scripts should be checked for mathematical errors. Please adopt a system of one tick () equals 1 mark, e.g. if you have awarded 4 marks for part of a question then 4 ticks () should be on this candidate’s answer.
3. The total mark for each question should be recorded in a circle placed opposite the question number in the teacher mark column.
4. As candidates have access to scripts please do not write any inappropriate comments on their scripts.
General points
• All calculations are marked according to the number of errors made.
• Errors can be carried through. If the wrong calculation is carried out then the incorrect answer can be carried through. One mistake at the start of a question does not always mean that all marks are lost.
• Any number of decimal places may be used provided the ‘rounding’ is correct.
• Listing is when more than one answer is given for a question that only requires one answer, e.g. the precipitate from a chloride with silver nitrate is a white solid; if the candidate states a white or a cream solid, one answer is correct and one answer is wrong. Hence they cancel out.
• Although names might be in the mark scheme it is generally accepted that formulae can replace them. Formulae and names are often interchangeable in chemistry.
• The marking of colours is defined in the ‘CCEA GCE Chemistry Acceptable Colours’ document.
MARKING GUIDELINES
Interpretation of the Mark Scheme
• Carry error through This is where mistakes/wrong answers are penalised when made, but if carried
into further steps of the question, then no further penalty is applied. This pertains to calculations and observational/deduction exercises. Please annotate candidates’ answers by writing the letters c.e.t. on the appropriate place in the candidates’ answers.
• Oblique/forward slash This indicates an acceptable alternative answer(s).
• Brackets Where an answer is given in the mark scheme and is followed by a word/words in
brackets, this indicates that the information within the brackets is non-essential for awarding the mark(s).
9568.01 F 3
AVAILABLEMARKS
9568.01 F 3 [Turn over
Titration Exercise
1 Table [3]
The Table should be drawn as a boxed table. It should be labelled with the following:
initial burette reading, final burette reading and the titre. It is not necessary to use exactly these words but there should be appropriate columns and rows. The recorded readings should be checked for mathematical accuracy [1].
The rough titration value should be greater than the accurate values (no more than 2 cm3) [1]. If rough less than accurate [–1].
Units, i.e. cm3, should be stated in each column/row [1].
Use of decimal places [2] All burette readings should be to at least one decimal place – each mistake is penalised by one mark. (However initial burette readings of 0 are penalised once only.) If used, the second decimal place position should be 0 or 5 only – other values will be penalised by 1 mark for each.
Average titre [2] Accurate titrations only should be used. All accurate titration values should be
used. The use of a rough value is [–1].
The average value can be calculated to two decimal places or more, e.g. 25.15 and 25.20 would average to 25.175. If three (or more) accurate titres are recorded, then the average titre must be calculated using all three (or more) accurate titres. Any error is [–1]. This might be an incorrect calculation or the omission of units. If the average titre is included in the table then the units indicated on the table apply.
Titration consistency [1] This is the difference within the accurate titrations. If three (or more) accurate
values are given then the difference between highest and lowest is used.
Difference Mark 0.3 [1] >0.3 [0] This value of 0.1 might need to be raised in the light of candidate response. [8] 8
9568.01 F 4 [Turn over
AVAILABLEMARKS
2 (a) Test Observations
1 Describe the appearance of X. (Pale) green (crystals) [1]
2 Add 3 spatula measures of X to 20 cm3 of water and stir until there is no further change. Use this solution for tests 3, 4 and 5.
Yellow/green solution
[1]
3 (a) In a fume cupboard add 5 drops of concentrated ammonia solution to 2 cm3 of the solution of X in a test tube.
(b) Add a further 5 cm3 of concentrated ammonia solution to the test tube.
Green precipitate [1]
Precipitate colour darkens/remains [1]
4 (a) Add 5 drops of sodium hydroxide solution to 2 cm3 of the solution of X in a test tube.
(b) Add a further 5 cm3 of sodium hydroxide solution to the test tube.
Green precipitate [1]
Precipitate remains [1]
5 Add 2 cm3 of barium chloride solution to a test tube containing 2 cm3 of the solution of X.
White precipitate [1]
6 Place a half spatula measure of X onto a watch glass in a fume cupboard. In the fume cupboard and wearing gloves, slowly add 10 drops of concentrated sulfuric acid.
White solid [1] – not crystals
7 Place a spatula measure of X in a dry boiling tube. Heat the boiling tube gently.
White solid [1] – not crystals
Colourless liquid forms on walls of tube [1]
(b) Water bath filled using hot water from a kettle.
Test Observations
1 Add 10 drops of Y to 2 cm3 of acidified potassium dichromate solution in a test tube. Place the test tube in a hot water bath for 5 minutes.
(Orange to) green [1]
2 Add 1 cm3 of Y to 2 cm3 of Fehling's solution in a test tube. Place the test tube in a hot water bath for 5 minutes.
Red precipitate [1]
12
Total 20
MARKSCHEME
Standardising Meeting Version
9569.01 F
ADVANCEDGeneral Certificate of Education
2015
ChemistryAssessment Unit A2 3
assessing
Module 3: Practical ExaminationPractical Booklet B
[AC234]
MONDAY 11 MAY, MORNING
29569.01 F
Annotation
1. Please do all marking in red ink.
2. All scripts should be checked for mathematical errors. Please adopt a system of one tick () equals 1 mark, e.g. if you have awarded 4 marks for part of a question then 4 ticks () should be on this candidate’s answer.
3. The total mark for each question should be recorded in a circle placed opposite the question number in the teacher mark column.
4. As candidates have access to scripts please do not write any inappropriate comments on their scripts.
General points
• All calculations are marked according to the number of errors made.
• Errors can be carried through. If the wrong calculation is carried out then the incorrect answer can be carried through. One mistake at the start of a question does not always mean that all marks are lost.
• Any number of decimal places may be used provided the ‘rounding’ is correct.
• Listing is when more than one answer is given for a question that only requires one answer, e.g. the precipitate from a chloride with silver nitrate is a white solid; if the candidate states a white or a cream solid, one answer is correct and one answer is wrong. Hence they cancel out.
• Although names might be in the mark scheme it is generally accepted that formulae can replace them. Formulae and names are often interchangeable in chemistry.
• The marking of colours is defined in the ‘CCEA GCE Chemistry Acceptable Colours’ document.
MARKING GUIDELINES
Interpretation of the Mark Scheme
• Carry error through This is where mistakes/wrong answers are penalised when made, but if carried into further steps of the question, then no further penalty is applied. This pertains to calculations and observational/deduction exercises. Please annotate candidates’ answers by writing the letters c.e.t. on the appropriate place in the candidates’ answers.
• Oblique/forward slash This indicates an acceptable alternative answer(s).
• Brackets Where an answer is given in the mark scheme and is followed by a word/words in brackets, this indicates that the information within the brackets is non-essential for awarding the mark(s).
3
AVAILABLE MARKS
9569.01 F
1 (a) (i) 5Fe2+ + MnO4– + 8H+ → 4H2O + 5Fe3+ + Mn2+ [2]
(ii) pink [1]
(iii) MnO4– [1]
(iv) Performing a rough titration [1] adding dropwise before the endpoint [1] repeat for values within 0.1 cm3 [1] Any 2 from 3 [2] (b) Weigh (6.0g of) tablets on a balance In a beaker add (50 cm3) of deionised water to the tablets _`
a
Stir to dissolve Transfer with washings into a 250 cm3 volumetric flask _
`a Make up to the mark with deionised water/bottom of meniscus on line
(Stopper) and invert max [4]
(c) 22.4/1000 × 0.02 = 0.000448 Moles Fe2+ = 0.000448 × 5 = 0.00224 in 25 cm3
= 0.0224 in 250 cm3
RFM FeSO4.6H2O = 260 Mass FeSO4 = 0.0224 × 260 = 5.824g % = 5.824/6.00 × 100 = 97.07% [4]
(d) (i) blood red (solution) [1]
(ii) [Fe(H2O)6]3+ + SCN– → [Fe(H2O)5(SCN)]2+ + H2O [2] 17
4
AVAILABLE MARKS
9569.01 F
2 (a) (i) Based on the following observations, make deductions for salt A.
Test Deductions
1 Dissolve A in 20 cm3 of water
2 Add a few drops of concentrated ammonia solution to 2 cm3 of the solution of A in a test tube.
Confirms Fe3+/iron(III) hydroxide formed [1]/Fe(III)
3 Add 1 cm3 of barium chloride solution to 2 cm3 of the solution of A in a test tube, allow the mixture to settle.
Sulfate (ions) present [1]
(ii) Fe2(SO4)3 [1]
5
AVAILABLE MARKS
9569.01 F
(b) (i) Interpret the following data and identify the structural formula of the organic compound B, which has the empirical formula C2H4O.
Test Observations Deductions
1 Describe the appearance of B.
Colourless liquid.
Pungent smell
2 Add 2 cm3 of deionised water to 2 cm3 of B in a test tube
One layer forms. B is miscible with water/completely soluble/–OH group present/can hydrogen bond (with water). [1]
3 Add 10 drops of B to 2 cm3 of acidifi ed potassium
dichromate solution in a test tube. Place the test tube in a hot water bath.
Solution stays orange.
Not an aldehyde or primary or secondary alcohol/ Possibly a tertiary alcohol/ketone/ carboxylic acid. [1]
4 Place 2 cm3 of B into a test tube. In a fume cupboard cautiously add a very small spatula measure of phosphorus(V) chloride to the test tube.
Fizzing.
Solid dissolves.
White fumes.
–OH present. –COOH present.
[1]
5 Place 5 cm3 of B in a boiling tube. Add 5 cm3 of ethanol, and then 1 cm3 of concentrated sulfuric acid. Heat the boiling tube in a water bath. Cautiously smell the contents of the boiling tube.
Sweet smell Ester (produced).–COOH present.
[1]
6 Add a spatula measure of sodium carbonate to 2 cm3 of B in a test tube.
Fizzing.
Solid dissolves.
CO2 released.
B is a carboxylic acid. [2]
(ii) Carboxylic acid(s) [1]
(iii)
CC
H H
C
H
H H
O
H O H
H
C
or
CH
H H
C
O
O H
H
C
C HH
H
[2]
(iv) +CH2COOH/CH2COOH+/C2H3O2+ [1] 13
6
AVAILABLE MARKS
9569.01 F
3 (a) Ammonia is a nucleophile [1]
(b) (i) Repeated boiling and condensing of a reaction mixture. [1]
(ii)Thermometer
Distillate/nitrobenzene
Heat
Condenser
Round-bottomed flask
Reaction mixture
no heat source [–1] no double jacket on condenser [–1] distillation fl ask open at top [–1] thermometer missing [–1], bulb not opposite side arm [–1] no labels [–1] If water in and out IS shown [–1] sealed apparatus [–1] continuous connection to and from condenser [–1] – penalise once [4]
(c) moles nitrobenzene = 7/123 = 0.057 moles (90%) 100% = 0.063 moles Moles benzene = 0.063 Mass benzene = 0.063 × 78 = 4.91 g Vol = mass/density = 4.91/0.88 = 5.58 cm3 [4]
(d) Place in separating funnel [1] Add sodium carbonate/hydrogencarbonate solution [1] Stopper, invert (and shake) Open tap (to release pressure) [1] Run off (lower) layer [1] [4]
Quality of written communication [2] (e) (i)
[2]
(ii) potassium iodide, aqueous [1] allow to warm up/heat/reflux [1] [2] 20
Total 50
+N N
6
MARKSCHEME
Standardising Meeting Version
9569.01 F
ADVANCEDGeneral Certificate of Education
2015
ChemistryAssessment Unit A2 3
assessing
Module 3: Practical ExaminationPractical Booklet B
[AC234]
MONDAY 11 MAY, MORNING
29569.01 F
Annotation
1. Please do all marking in red ink.
2. All scripts should be checked for mathematical errors. Please adopt a system of one tick () equals 1 mark, e.g. if you have awarded 4 marks for part of a question then 4 ticks () should be on this candidate’s answer.
3. The total mark for each question should be recorded in a circle placed opposite the question number in the teacher mark column.
4. As candidates have access to scripts please do not write any inappropriate comments on their scripts.
General points
• All calculations are marked according to the number of errors made.
• Errors can be carried through. If the wrong calculation is carried out then the incorrect answer can be carried through. One mistake at the start of a question does not always mean that all marks are lost.
• Any number of decimal places may be used provided the ‘rounding’ is correct.
• Listing is when more than one answer is given for a question that only requires one answer, e.g. the precipitate from a chloride with silver nitrate is a white solid; if the candidate states a white or a cream solid, one answer is correct and one answer is wrong. Hence they cancel out.
• Although names might be in the mark scheme it is generally accepted that formulae can replace them. Formulae and names are often interchangeable in chemistry.
• The marking of colours is defined in the ‘CCEA GCE Chemistry Acceptable Colours’ document.
MARKING GUIDELINES
Interpretation of the Mark Scheme
• Carry error through This is where mistakes/wrong answers are penalised when made, but if carried into further steps of the question, then no further penalty is applied. This pertains to calculations and observational/deduction exercises. Please annotate candidates’ answers by writing the letters c.e.t. on the appropriate place in the candidates’ answers.
• Oblique/forward slash This indicates an acceptable alternative answer(s).
• Brackets Where an answer is given in the mark scheme and is followed by a word/words in brackets, this indicates that the information within the brackets is non-essential for awarding the mark(s).
3
AVAILABLE MARKS
9569.01 F
1 (a) (i) 5Fe2+ + MnO4– + 8H+ → 4H2O + 5Fe3+ + Mn2+ [2]
(ii) pink [1]
(iii) MnO4– [1]
(iv) Performing a rough titration [1] adding dropwise before the endpoint [1] repeat for values within 0.1 cm3 [1] Any 2 from 3 [2] (b) Weigh (6.0g of) tablets on a balance In a beaker add (50 cm3) of deionised water to the tablets _`
a
Stir to dissolve Transfer with washings into a 250 cm3 volumetric flask _
`a Make up to the mark with deionised water/bottom of meniscus on line
(Stopper) and invert max [4]
(c) 22.4/1000 × 0.02 = 0.000448 Moles Fe2+ = 0.000448 × 5 = 0.00224 in 25 cm3
= 0.0224 in 250 cm3
RFM FeSO4.6H2O = 260 Mass FeSO4 = 0.0224 × 260 = 5.824g % = 5.824/6.00 × 100 = 97.07% [4]
(d) (i) blood red (solution) [1]
(ii) [Fe(H2O)6]3+ + SCN– → [Fe(H2O)5(SCN)]2+ + H2O [2] 17
4
AVAILABLE MARKS
9569.01 F
2 (a) (i) Based on the following observations, make deductions for salt A.
Test Deductions
1 Dissolve A in 20 cm3 of water
2 Add a few drops of concentrated ammonia solution to 2 cm3 of the solution of A in a test tube.
Confirms Fe3+/iron(III) hydroxide formed [1]/Fe(III)
3 Add 1 cm3 of barium chloride solution to 2 cm3 of the solution of A in a test tube, allow the mixture to settle.
Sulfate (ions) present [1]
(ii) Fe2(SO4)3 [1]
5
AVAILABLE MARKS
9569.01 F
(b) (i) Interpret the following data and identify the structural formula of the organic compound B, which has the empirical formula C2H4O.
Test Observations Deductions
1 Describe the appearance of B.
Colourless liquid.
Pungent smell
2 Add 2 cm3 of deionised water to 2 cm3 of B in a test tube
One layer forms. B is miscible with water/completely soluble/–OH group present/can hydrogen bond (with water). [1]
3 Add 10 drops of B to 2 cm3 of acidifi ed potassium
dichromate solution in a test tube. Place the test tube in a hot water bath.
Solution stays orange.
Not an aldehyde or primary or secondary alcohol/ Possibly a tertiary alcohol/ketone/ carboxylic acid. [1]
4 Place 2 cm3 of B into a test tube. In a fume cupboard cautiously add a very small spatula measure of phosphorus(V) chloride to the test tube.
Fizzing.
Solid dissolves.
White fumes.
–OH present. –COOH present.
[1]
5 Place 5 cm3 of B in a boiling tube. Add 5 cm3 of ethanol, and then 1 cm3 of concentrated sulfuric acid. Heat the boiling tube in a water bath. Cautiously smell the contents of the boiling tube.
Sweet smell Ester (produced).–COOH present.
[1]
6 Add a spatula measure of sodium carbonate to 2 cm3 of B in a test tube.
Fizzing.
Solid dissolves.
CO2 released.
B is a carboxylic acid. [2]
(ii) Carboxylic acid(s) [1]
(iii)
CC
H H
C
H
H H
O
H O H
H
C
or
CH
H H
C
O
O H
H
C
C HH
H
[2]
(iv) +CH2COOH/CH2COOH+/C2H3O2+ [1] 13
6
AVAILABLE MARKS
9569.01 F
3 (a) Ammonia is a nucleophile [1]
(b) (i) Repeated boiling and condensing of a reaction mixture. [1]
(ii)Thermometer
Distillate/nitrobenzene
Heat
Condenser
Round-bottomed flask
Reaction mixture
no heat source [–1] no double jacket on condenser [–1] distillation fl ask open at top [–1] thermometer missing [–1], bulb not opposite side arm [–1] no labels [–1] If water in and out IS shown [–1] sealed apparatus [–1] continuous connection to and from condenser [–1] – penalise once [4]
(c) moles nitrobenzene = 7/123 = 0.057 moles (90%) 100% = 0.063 moles Moles benzene = 0.063 Mass benzene = 0.063 × 78 = 4.91 g Vol = mass/density = 4.91/0.88 = 5.58 cm3 [4]
(d) Place in separating funnel [1] Add sodium carbonate/hydrogencarbonate solution [1] Stopper, invert (and shake) Open tap (to release pressure) [1] Run off (lower) layer [1] [4]
Quality of written communication [2] (e) (i)
[2]
(ii) potassium iodide, aqueous [1] allow to warm up/heat/reflux [1] [2] 20
Total 50
+N N
6