ERRATUM NOTICE ﬁ Chemistry, Assessment Unit AS3, Module 3 ... · Chemistry, Assessment Unit AS3, Module 3, Practical Examination 1 (ASC31) Monday 12 May, Afternoon Notice to Invigilator

ERRATUM NOTICE

General Certifi cate of Education (Advanced Subsidiary)Chemistry, Assessment Unit AS3, Module 3, Practical Examination 1

(ASC31)

Monday 12 May, Afternoon

Notice to Invigilator

Before the start of the examination the following should be read to candidates.

1. Go to the Question Paper. (Pause)

2. Turn to page 3 of the Question Paper. (Pause)

3. Go to experiment number 5. (Pause)

4. The third line reads “Add 10 drops of Y”. (Pause)

5. This should read “Add 10 drops of B”. (Pause)

Repeat

1. Go to the Question Paper. (Pause)

2. Turn to page 3 of the Question Paper. (Pause)

3. Go to experiment number 5. (Pause)

4. The third line reads “Add 10 drops of Y”. (Pause)

5. This should read “Add 10 drops of B”. (Pause)

Please make this change in your question paper now.

This is the end of the announcement.

For Examiner’s use only

Question Marks

Number

1

2

3

4

TotalMarks

71

Centre Number

Candidate Number

ADVANCED SUBSIDIARY (AS)General Certificate of Education

2008

Chemistry

Assessment Unit AS 3

assessing

Module 3: Practical Examination 1

[ASC31]

MONDAY 12 MAY, AFTERNOON

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 four questions.

Write your answers in the spaces provided.

INFORMATION FOR CANDIDATES

The total mark for this paper is 90.

Questions 1 and 2 are practical exercises each worth 25 marks.

Question 3 is a planning exercise worth 20 marks.

Question 4 is a written question testing aspects of experimental

chemistry worth 20 marks.

You may have access to notes, textbooks and other materials to assist

you.

A Periodic Table of Elements (including some data) is provided.

AS

C31

ASC3S8 3697R

ASC3S8 3697R 2 [Turn over

Experiment Observations Deductions

1 Describe the appearance of A.

2 (a) Add half a spatula-measure

of A to a test tube half-full

of sodium hydroxide

solution and warm gently.

(b) Test the gas evolved with

damp Universal Indicator

paper.

(c) Test the gas evolved by

dipping a glass rod into

concentrated hydrochloric

acid and holding it over the

mouth of the test tube.

3 Dip a nichrome wire loop into

concentrated hydrochloric

acid; touch sample A with the

wire, then hold it in a blue

Bunsen flame.

4 Dissolve half a spatula-

measure of A in about 2cm3

of dilute nitric acid. Add 2cm3

of barium chloride solution.

1 Observation/deduction

Safety goggles must be worn at all times during this practical examination.

Care should be exercised, especially when using sodium hydroxide solution and

concentrated hydrochloric acid.

(a) You are provided with 2 g of a mixture, labelled A, which contains two salts with

a common anion, but different cations. Carry out the following experiments on the

mixture.

Record your observations and deductions in the spaces below and identify the two salts

in A.

Name the two salts present in A ______________________________________________

Name the two salts in X ______________________________________________


Functional group in B ______________________________________________________

Class of compounds ______________________________________________________

Structure of B __________________________________________________ [25]

(b) You are provided with an organic liquid labelled B which has the formula C3H

8O. Carry

out the following experiments. Record your observations and deductions in the spaces

below. Suggest a structure for B. On completion of your experiments, dispose of B in

the container provided.

Experiment Observations Deductions

1 Describe the liquid B.

2 Add 2 cm3 of B to 2 cm3 of

water.

3 Place 5 drops of B on a watch

glass placed on a heatproof

mat and ignite using a splint.

4 Add 1 cm3 of dilute sulphuric

acid to 2 cm3 of potassium

dichromate solution. Add

10 drops of B and warm

gently.

5 Add 1 cm3 of a solution of

iodine in potassium iodide.

Add 10 drops of Y followed

by 1 cm3 of sodium hydroxide

solution. Add 1 cm3 of sodium

hypochlorite solution.


2 Titration

(a) You are provided with:

hydrochloric acid of unknown concentration, but approximately 2 mol dm–3,

sodium carbonate solution of concentration 0.1 mol dm–3,

methyl orange indicator.

You are required to:

(i) dilute the hydrochloric acid using a pipette and a volumetric flask.

(ii) titrate the sodium carbonate solution against the diluted hydrochloric acid using

methyl orange as indicator.

Procedure

(i) Dilution

• Using the pipette and pipette filler, place 25.0 cm3 of the hydrochloric acid in a

250 cm3 volumetric flask.

• Add deionised water to the flask, inverting the flask as the level approaches the

mark. Fill to the mark with deionised water. Stopper and mix well by inversion.

(ii) Titration

• Rinse out the burette with the 0.1 mol dm–3 sodium carbonate solution.

• Fill the burette with 0.1 mol dm–3 sodium carbonate solution.

• Rinse out the pipette with diluted hydrochloric acid solution.

• Using the pipette and a pipette filler, place 25.0 cm3 of the diluted hydrochloric acid

solution in the conical flask.

• Add 2 or 3 drops of the methyl orange indicator to the conical flask and titrate with

the 0.1 mol dm–3 sodium carbonate solution until the end point is reached.

• Record the results of one rough and two accurate titrations in the table.

0.1 mol dm–3 sodium

carbonate solution

diluted hydrochloric acid

and methyl orange

dilute

hydrochloric acid


Examiner Only

Marks Remark

1 –

12.0

1.07

/ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

– 1

2.01

.07/

ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

Results

Initial burettereading/cm3

Final burettereading/cm3 Titre/cm3

Rough

1st accurate

2nd accurate

Average titre ___________ cm3 [15]

(b) State the colour change at the end point.

From __________________ to __________________ [1]

(c) (i) Write an equation for the reaction of hydrochloric acid with

sodium carbonate.

___________________________________________________[2]

(ii) Using the average titre, calculate the number of moles of sodium

carbonate used.

___________________________________________________[1]

(iii) Use the ratio in which the hydrochloric acid reacts with sodium

carbonate to calculate the number of moles of hydrochloric acid

present in 25.0 cm3 of diluted solution.

_____________________________________________________

___________________________________________________[2]


Examiner Only

Marks Remark

1 –

12.0

1.07

/ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

– 1

2.01

.07/

ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

(iv) Calculate the number of moles of hydrochloric acid present in the

250 cm3 volumetric flask.

_____________________________________________________

___________________________________________________[2]

(v) Calculate the concentration, in mol dm–3, of the undiluted

hydrochloric acid.

___________________________________________________[1]

(vi) Calculate the concentration, in g dm–3, of the undiluted

hydrochloric acid.

___________________________________________________[1]


BLANK PAGE

(Questions continue overleaf)


Examiner Only

Marks Remark

1 –

12.0

1.07

/ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

– 1

2.01

.07/

ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

3 Planning

You are required to plan an experiment to find the enthalpy of combustion

of a series of simple alcohols using a simple calorimeter. Apparatus I or II

could be used to carry out the experiment.

(a) (i) State the purpose of the two pieces of apparatus labelled A.

___________________________________________________[1]

(ii) Explain why the piece of apparatus labelled A in apparatus II is

more efficient than that in apparatus I.

___________________________________________________[1]

(iii) Explain why the piece of apparatus labelled B in apparatus II is

more efficient than that in apparatus I.

___________________________________________________[1]

(iv) Explain the purpose of the screens.

___________________________________________________[1]

thermometerthermometer

waterwater

screen

screen

ethanolethanol

I II

A A

B

B


Examiner Only

Marks Remark

1 –

12.0

1.07

/ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

– 1

2.01

.07/

ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

(b) The following results were obtained in an experiment using ethanol:

Initial mass of ethanol = 19.8 g

Final mass of ethanol = 19.6 g

Initial temperature = 22 °C

Final temperature = 33 °C

Mass of water = 0.10 kg

(i) What mass of ethanol was burned?

___________________________________________________[1]

(ii) How many moles of ethanol were burned?

__________________________________________________ [1]

(iii) What was the temperature rise during the experiment?

__________________________________________________ [1]

(iv) Calculate the molar enthalpy of combustion of ethanol.

The specific heat capacity of water = 4.18 � 10 3 J kg–1 K–1 at 293 K.

Heat received by water = mass of water � temperature rise �

specific heat capacity of water.

_____________________________________________________

_____________________________________________________

___________________________________________________[3]

(v) Explain why the theoretical value for the combustion of ethanol is

different from the experimental value.

___________________________________________________[1]


Examiner Only

Marks Remark

1 –

12.0

1.07

/ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

– 1

2.01

.07/

ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

(c) (i) Write the equation for the complete combustion of ethanol.

__________________________________________________ [2]

(ii) Name the gas produced, apart from water vapour, in the complete

combustion of ethanol.

__________________________________________________ [1]

(iii) How would you confirm the identity of this gas using a chemical

test? State what would be observed.

_____________________________________________________

___________________________________________________[2]

(d) When ethanol is used as a fuel in camping stoves, a black deposit

of carbon is formed on the base of the cooking pots. When a small

amount of water is added to the ethanol, and this mixture burned, no

carbon deposit is observed. It has been suggested that the carbon reacts

with steam to produce carbon monoxide together with another gas.

(i) Write an equation for the incomplete combustion of ethanol, in

which carbon is one of the products.

__________________________________________________ [2]

(ii) Suggest an equation for the reaction between carbon and steam.

__________________________________________________ [2]


1 –

12.0

1.07

/ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

– 1

2.01

.07/

ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

BLANK PAGE

(Questions continue overleaf)


Examiner Only

Marks Remark

1 –

12.0

1.07

/ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

– 1

2.01

.07/

ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

4 Structured

The following method can be used to prepare 1-bromobutane:

CH3CH

2CH

2CH

2OH + HBr → CH

3CH

2CH

2CH

2Br + H

2O

Mr = 74 Mr = 137

Place 3 cm3 of butan-1-ol (density = 0.8 g cm–3) in a 25 cm3 flask. Weigh out 4.0 g of sodium bromide and add it and 4.5 cm3 of water to the butan-1-ol. Add 3.5 cm3 of concentrated sulphuric acid to form hydrobromic acid in situ. Add boiling chips, attach a condenser to the flask, and reflux the mixture for 45 minutes. Replace the condenser with a distillation setup, and distil the 1-bromobutane and water at a temperature below 110 °C into a 10 cm3 flask, cooled in an ice-water bath. Add about 1 g of sodium sulphate to the distillate, and swirl the mixture. Transfer the 1-bromobutane to a test tube, add 1.5 cm3 of conc. sulphuric acid. Mix the two layers thoroughly. Place the test tube in an ice-water bath and allow the layers to separate. Draw off the sulphuric acid and discard it into a beaker half-filled with ice. Add about 0.5 g of sodium sulphate to the 1-bromobutane, and after several minutes add 0.5 g of potassium carbonate and mix well. Transfer the 1-bromobutane to a 10 cm3 flask. Set up the distillation apparatus as before and distil. Determine the mass of product.

(a) (i) Write an equation to show how the hydrobromic acid is formed.

__________________________________________________ [2]

(ii) Suggest the meaning of the term in situ.

__________________________________________________ [1]

(b) Why are boiling chips added?

______________________________________________________ [1]

(c) (i) Draw a labelled diagram of the apparatus used to reflux the

mixture.

[3]

Examiner Only

Marks Remark

1 –

12.0

1.07

/ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

– 1

2.01

.07/

ES

2

– 9

.02.

07/R

TS

3 –

2.03

.07/

EA

(ii) State three changes made to the apparatus in order to set it up for

distillation.

_____________________________________________________

_____________________________________________________

___________________________________________________[3]

(d) What is the function of the sodium sulphate?

______________________________________________________ [1]

(e) Why should the receiver flask be clean and dry?

______________________________________________________ [2]

(f) A student following these instructions obtained 3.55 g of

1-bromobutane.

(i) Calculate the number of moles of butan-1-ol used.

___________________________________________________[2]

(ii) Calculate the number of moles of 1-bromobutane formed.

___________________________________________________[1]

(iii) Assuming that the hydrobromic acid was in excess, calculate the

percentage yield of the 1-bromobutane. _____________________________________________________

_____________________________________________________

___________________________________________________[1]

(g) Referring to practical and theoretical considerations, suggest why the

percentage yield is not 100%.

Practical _________________________________________________

_________________________________________________________

Theoretical _______________________________________________

______________________________________________________ [3]

ASC3S8 3697R 13


THIS IS THE END OF THE QUESTION PAPER

S – 6/07 – 528-005-1 [Turn over

ADVANCED SUBSIDIARY (AS)General Certificate of Education

2008

Chemistry

Assessment Unit AS 3assessing

Module 3: Practical Examinations 1 and 2

[ASC31] [ASC32]

MONDAY 12 MAY AND FRIDAY 16 MAY

APPARATUSAND

MATERIALSLIST

ASC3S8/ASC3aS8 3697.02

ASC3S8/ASC3aS8 3697.02 2 [Turn over

Advice for centres

● All chemicals used should be at least laboratory reagent specification and labelled with

appropriate safety symbols, e.g. irritant.

● Apparatus and reagents should be available for the identification tests of the gases listed in

Section 2.10 of the specification, i.e. H2, O

2, Cl

2, CO

2, SO

2, HCl, NH

3.

● 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.


Practical Examination 1

Each candidate must be supplied with safety goggles or glasses.

Question No. 1

Each candidate must be supplied with:

● eight test tubes (125 mm length × 16 mm OD would be suitable);

● a test tube holder;

● a test tube rack;

● a spatula;

● nichrome wire;

● a heat-proof mat;

● a Bunsen burner;

● a wooden splint;

● a glass rod;

● two watch-glasses;

● a wash bottle containing deionised water;

● three droppers with teats;

● about 3.0 g of a mixture of 1.5 g ammonium sulphate and 1.5 g anhydrous sodium sulphate in

a 50/100 cm3 beaker labelled A;

● about 10 cm3 of dilute nitric acid in a reagent bottle/beaker labelled dilute nitric acid and

irritant. This solution should be approximately 2 M;

● about 10 cm3 of barium nitrate solution in a reagent bottle/beaker labelled barium chloride solution. This solution should be approximately 0.1 M (20.8 g dm–3 for BaCl

2);

● about 10 cm3 of concentrated hydrochloric acid in a stoppered reagent bottle labelled

concentrated hydrochloric acid and corrosive/irritant;

● about 10 cm3 of propan-2-ol in a stoppered container labelled B and flammable;


● about 5 cm3 of potassium dichromate(VI) solution in a stoppered reagent bottle labelled

potassium dichromate(VI) solution and irritant. This solution should be about 0.1 M

(29.4 g dm–3);

● about 5 cm3 of dilute sulphuric acid in a reagent bottle labelled dilute sulphuric acid and

irritant. This solution should be approximately 1 mol dm–3;

● Universal indicator paper;

● about 10 cm3 of sodium hydroxide solution in a reagent bottle labelled dilute sodium hydroxide and corrosive/irritant. This solution should be approximately 0.5 mol dm–3;

● about 5 cm3 of a solution of iodine in potassium iodide (3.0 g of potassium iodide and 2.5 g

of iodine in 100 cm3 of water) labelled iodine in potassium iodide;

● about 5 cm3 of sodium hypochlorite solution (1% w/v) labelled sodium hypochlorite solution and corrosive/irritant.

Question No. 2


● one 50 cm3 burette of at least class B quality;

● one 25 cm3 pipette of at least class B quality;

● one 250 cm3 volumetric flask;

● a safety pipette filler;

● three conical flasks of 250 cm3 capacity;

● a funnel for filling the burette (optional);

● a white tile or white paper;

● two beakers of 100 cm3 capacity;

● a wash bottle containing deionised/distilled water;

● a retort stand and clamp;

● 150 cm3 of 0.1 mol dm–3 sodium carbonate solution labelled sodium carbonate solution 0.1 mol dm–3 and corrosive/irritant;

● 150 cm3 of dilute hydrochloric acid labelled hydrochloric acid and irritant. The diluted

acid should be approximately 2 mol dm–3 and can be prepared by the dilution of the

concentrated acid;

● Phenolphthalein indicator.


Practical Examination 2

Each candidate must be supplied with safety goggles or glasses.

Question No. 1


● eight test tubes (125 mm length × 16 mm OD would be suitable);

● a test tube holder;

● a test tube rack;

● a spatula;

● nichrome wire;

● a heat-proof mat;

● a Bunsen burner;

● a wooden splint;

● a glass rod;

● two watch-glasses;

● a wash bottle containing deionised water;

● three droppers with teats;

● about 3.0 g of a mixture of 1.5 g potassium chloride and 1.5 g ammonium chloride in a

50/100 cm3 beaker labelled X;

● about 10 cm3 of silver nitrate solution in a reagent bottle/beaker labelled silver nitrate solution. This solution should be approximately 0.1 M (17.0 g dm–3);

● about 10 cm3 of dilute nitric acid in a reagent bottle/beaker labelled dilute nitric acid and irritant. This solution should be approximately 2 M;

● about 10 cm3 of concentrated hydrochloric acid in a stoppered reagent bottle labelled

concentrated hydrochloric acid and corrosive/irritant;

● about 10 cm3 of propan-1-ol in a stoppered container labelled B and flammable;

● about 5 cm3 of potassium dichromate(VI) solution in a stoppered reagent bottle labelled

potassium dichromate(VI) solution and irritant. This solution should be about 0.1 M

(29.4 g dm–3);


● about 5 cm3 of dilute sulphuric acid in a reagent bottle labelled dilute sulphuric acid and

irritant. This solution should be approximately 1 mol dm–3;

● Universal indicator paper;

● about 10 cm3 of sodium hydroxide solution in a reagent bottle labelled dilute sodium hydroxide and corrosive/irritant. This solution should be approximately 0.5 mol dm–3;

● about 5 cm3 of a solution of iodine in potassium iodide (3.0 g of potassium iodide and 2.5 g

of iodine in 100 cm3 of water) labelled iodine in potassium iodide;

● about 5 cm3 of sodium hypochlorite solution (1% w/v) labelled sodium hypochlorite solution and corrosive/irritant.

Question No. 2


● one 50 cm3 burette of at least class B quality;

● one 25 cm3 pipette of at least class B quality;

● one 250 cm3 volumetric flask;

● a safety pipette filler;

● three conical flasks of 250 cm3 capacity;

● a funnel for filling the burette (optional);

● a white tile or white paper;

● two beakers of 100 cm3 capacity;

● a wash bottle containing deionised/distilled water;

● a retort stand and clamp;

● 150 cm3 of 0.1 mol dm–3 sodium hydroxide solution labelled sodium hydroxide solution 0.1 mol dm–3 and corrosive/irritant;

● 150 cm3 of dilute sulphuric acid labelled sulphuric acid and irritant. The diluted acid should be approximately 0.5 mol dm–3 and can be prepared by the dilution of the concentrated acid;

● Methyl orange indicator.

S – 1/08 – 528-023-1 [Turn over

Documents

ERRATUM NOTICE ﬁ Chemistry, Assessment Unit AS3, Module 3 ... · Chemistry, Assessment Unit AS3, Module 3, Practical Examination 1 (ASC31) Monday 12 May, Afternoon Notice to Invigilator