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8/7/2019 Chem June 2010 MS
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Mark Scheme (Results)
June 2010
GCE
GCE Chemistry (6CH01/01)
Edexcel Limited. Registered in England and Wales No. 4496750Registered Office: One90 High Holborn, London WC1V 7BH
Click here for 6CH05 MS
Click here for 6CH04 MS
Click here for 6CH08 MS
Click here for 6CH01 MS
Click here for 6CH02 MS
Click here for 6CH07 MS
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Edexcel is one of the leading examining and awarding bodies in the UK and throughout theworld. We provide a wide range of qualifications including academic, vocational,occupational and specific programmes for employers.
Through a network of UK and overseas offices, Edexcel’s centres receive the support theyneed to help them deliver their education and training programmes to learners.
For further information, please call our GCE line on 0844 576 0025, our GCSE team on 0844576 0027, or visit our website at www.edexcel.com.
If you have any subject specific questions about the content of this Mark Scheme thatrequire the help of a subject specialist, you may find our Ask The Expert email servicehelpful.
Ask The Expert can be accessed online at the following link:
http://www.edexcel.com/Aboutus/contact-us/
Alternatively, you can speak directly to a subject specialist at Edexcel on our dedicatedScience telephone line: 0844 576 0037
Summer 2010
Publications Code US023629
All the material in this publication is copyright© Edexcel Ltd 2010
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Section A (multiple choice)
QuestionNumber
Correct Answer Mark
1 (a) B 1
QuestionNumber
Correct Answer Mark
1 (b) D 1
QuestionNumber
Correct Answer Mark
2 D 1
QuestionNumber
Correct Answer Mark
3 A 1
QuestionNumber
Correct Answer Mark
4 (a) B 1
QuestionNumber
Correct Answer Mark
4(b) D 1
QuestionNumber
Correct Answer Mark
4 (c) C 1
QuestionNumber
Correct Answer Mark
4 (d) A 1
QuestionNumber
Correct Answer Mark
5 B 1
QuestionNumber
Correct Answer Mark
6 A 1
QuestionNumber
Correct Answer Mark
7 C 1
QuestionNumber
Correct Answer Mark
8 D 1
Question
Number
Correct Answer Mark
9 C 1
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QuestionNumber
Correct Answer Mark
10 C 1
QuestionNumber
Correct Answer Mark
11 D 1
QuestionNumber
Correct Answer Mark
12 B 1
QuestionNumber
Correct Answer Mark
13 D 1
QuestionNumber
Correct Answer Mark
14 (a) B 1
QuestionNumber
Correct Answer Mark
14 (b) A 1
QuestionNumber
Correct Answer Mark
14 (c) C 1
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Section B
QuestionNumber
Acceptable Answers Reject Mark
15 (a)(i)
electrons (1) charge (1)
square brackets not essential
Mark independently
Ignore (labelling of) nucleus unless incorrect
2
QuestionNumber
Acceptable Answers Reject Mark
15 (a)(ii) 1s22s22p63s23p6
Allow electron number as sub script
Allow orbitals as capital letters
Allow TE from (a) (i) if Ca atom or Ca+ ion
1
QuestionNumber
Acceptable Answers Reject Mark
15 (a)(iii) Smaller
Because it has one less (sub) shell of electrons/ orbital / energy level / less shielding (1)
And the ratio of protons : electrons hasincreased/ more protons than electrons/ greater net force on remaining electrons (soremainder of electrons held more closely)/ greater effective nuclear charge (1)
bigger scoreszero
greater nuclearcharge /positivecharge
2
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QuestionNumber
Acceptable Answers Reject Mark
15 (a)(iv) Any two from:Strong (electrostatic) forces / attractions /bonds (between ions) (1)
(ions) held in giant lattice / many (ionic)attractions / forces / bonds (1)
So large amount of energy needed (to breakapart ions) (1)
Any mention of covalent ormetallic bondsor atoms ormoleculesscores zero
Hightemperature
2
Question
Number
Acceptable Answers Reject Mark
15 (b)(i) Because the ions are free to move (when apotential difference is applied)
Electrons /particles arefree to move
1
QuestionNumber
Acceptable Answers Reject Mark
15 (b)(ii) The cations / barium and calcium (ions) aredifferent sizes
Ignore any discussion of reasons
(could select either the calcium ion because ithas more water molecules associated with itOR the barium ion because it has more shellsof electrons and so larger)
Atoms aredifferent sizes
1
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QuestionNumber
Acceptable Answers Reject Mark
15 (b)(iii) Mass of calcium ions in 1 kg = 0.100 x 40 (= 4.0)(g) (1)
If mass quoted must be correct to score firstmark
Hence 4.0 g per 1000 g of solutionSo ppm = (4.0/1000) x 1000000= 4000 (ppm) (1)
ORMass of calcium ions in 1 kg = 0.100 x 40.1
(= 4.01) (g) (1)
Hence 4.01 g per 1000 g of solutionSo ppm = (4.01/1000) x 1000000= 4010 (ppm) (1)
Correct answer alone = 2 marks
Allow TE for second mark from incorrect mass
2
Question
Number
Acceptable Answers Reject Mark
15 (c) (Sulfur / nitrogen oxides) form when (fossil)fuels are burnt/ when petrol or diesel burn in vehicle engines/ emissions from vehicle (engines)/ volcanoes/ lightning (1)
They (react with water to) form sulfuric /sulfurous acid /nitric acid /acid rain / gases
are acidic (1)
Which reacts with limestone (to form solublecompounds) / limestone and acid take part inneutralisation / dissolves building / corrodesbuilding (1)
Allow correct equation for third mark butIgnore equations if mark already awarded.Ignore comments regarding erosion
from factoriesalone
3
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QuestionNumber
Acceptable Answers Reject Mark
15 (d) EitherYes, as the values match closely (so littledeviation from ionic model)Orno, as the values are (slightly) different so adegree of covalency / not fully ionic
100% ionic
covalent
1
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QuestionNumber
Acceptable Answers Reject Mark
16 (a) Atoms (of an element) with the same numberof protons (1)
But with different number of neutrons (1)
Same atomic number but different massnumber only = (1)
Element(s) with same number of protons butdifferent number of neutrons = (1) max
Ignore comments on electrons unless incorrectin which case award max 1
2
QuestionNumber
Acceptable Answers Reject Mark
16 (b)(i) (Electric field) accelerates ions 1
QuestionNumber
Acceptable Answers Reject Mark
16 (b) (ii) (Magnetic field) deflects / changes direction of / bends the beam of ions
if the term ‘ions’ is missing or an incorrectterm is used e.g. ‘atoms’, penalise only oncein parts b (i) and b (ii)
just bends ions 1
QuestionNumber
Acceptable Answers Reject Mark
16 (c) % abundance = (135 x 9.01 + 136 x 10.81 + 137
x 12.32 + 138 x 67.86) /100 (1)
= 137.4 (1)
ignore units
Allow TE for one slip in transfer of data fromquestion
Correct answer scores (2)
Just 137 as finalanswer137.39137.3903137.390
2
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QuestionNumber
Acceptable Answers Reject Mark
16 (d) three peaks (caused by Br2+ ions) (1)
because ions (79Br-79Br)(+) and (81Br-79Br)(+) / (79Br-81Br)(+) and (81Br-81Br)(+) (1)
Mark independently
2
QuestionNumber
Acceptable Answers Reject Mark
16 (e) Any one
analysis of material from space/ drug testing in sport/ identify breakdown products from drugs inbody/ quality control in pharmaceutical industry/ identify molecules from sample withpotential biological activity/ radioactive dating with context e.gdetermine age of fossils / human remains
The uses above must have a context
/ determining Mr of a molecule/ evidence for structure from fragmentationpattern
1
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QuestionNumber
Acceptable Answers Reject Mark
17 (a)
(1) for around carbon and its hydrogens(1) for around oxygen and its hydrogen
Allow all dots or all crossesIgnore circles around atoms
2
QuestionNumber
Acceptable Answers Reject Mark
17 (b)(i) C(s) / (graphite) + 2H2(g) + 2O2(g)Correct species (1)
Allow oxygen above arrows rather than in box
Balancing and state symbols (1)
Second mark dependent on correct speciesexcept as below with either hydrogen oroxygen or both as atomse.g
C(s) / (graphite) + 4H(g) + 4O(g)
Scores second mark
2
QuestionNumber
Acceptable Answers Reject Mark
17 (b)(ii) Enthalpy / energy / heat(energy) change whenone mole of a substance (1)
Is formed from its elements (in their moststable / standard states) (1)
Under standard conditions of 298K/ 25 ºC / anystated temperature AND 1 atm pressure /101 kPa / 100 kPa (1)
Definitions based on lattice enthalpies mayscore third mark only
heat required /heat given out /heat taken in
3
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QuestionNumber
Acceptable Answers Reject Mark
17 (b)(iii)!H!c = -!H1
! + !H2! (1)
= (2 x "285.8 + "393.5) " ("239.1)= "726 (1)Ignore units
Correct answer alone = 2 marks
+726 = 1
-440.2 = 1 if omit multiply by 2
2
QuestionNumber
Acceptable Answers Reject Mark
17 (c)(i) 20.7 x 200 x 4.18 = 17305(.2) (J)ignore sf except 1 sf i.e. 20000
OR
20.7 x 200 x 0.00418 = 17.305(2) kJignore sf except 1 sf i.e. 20
ignore signsignore mol"1
1
QuestionNumber
Acceptable Answers Reject Mark
17 (c) (ii) 0.848/32 = 0.0265 (mol)
ignore sf except 1 sf i.e. 0.03
1
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QuestionNumber
Acceptable Answers Reject Mark
17 (c)(iii) 17305.2/0.0265 = "653000 (J mol"1 ) (3sf)
OR
"653 (kJ mol"1) (3sf)
Ignore missing units but penalise incorrectunits
Allow TE from (c)(i) & (ii)
1
Question
Number
Acceptable Answers Reject Mark
17 (c)(iv) Any two from
As heat/energy absorbed by apparatus /heat/energy ‘lost’ to surroundings (1)
methanol not completely burnt / incompletecombustion (1)
methanol ‘lost’ by evaporation (1)
cannot ensure all products are at standardconditions at end of reaction / water isproduced as a gas / reaction not carried out inthe standard conditions (1)
justheat/energyloss
just incompletereaction
2
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QuestionNumber
Acceptable Answers Reject Mark
18 (a)(i) Crude oil / petroleum / coal Oil on its own /Natural gas /fossil fuels /any namedfraction of crude oil
1
QuestionNumber
Acceptable Answers Reject Mark
18 (a)(ii) use of high temperatures / heat (in theabsence of air) / thermal decomposition /
catalysts (1)
Either
to break large molecules / to form smallermolecules / to break bonds in large molecules/ to break carbon-carbon bonds (1)
OR
producing alkenes / producing carbon-carbondouble bonds (1)
2
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QuestionNumber
Acceptable Answers Reject Mark
18 (a)(iii) Risks (2) Amendments (2)
Risk Amendment
exposure to harmful /toxic fumes
Set up in fume cupboard
Escape of flammable /harmful / toxicreactants or productsfrom ill fitting bung
Correct fitting of bung
Escape of flammable /harmful /toxic reactantsor products from poorly
positioned delivery tube
Placement of deliverytube below mouth of test tube / use a longer
delivery tubesuck back Attach Bunsen valve /
remove delivery tubefrom water beforestopping heating etc
Mark all 4 points independentlyIf escaping gases linked to 2 amendments but no riskmentioned then allow 1 for risk
Dangerous
collect insyringe
4
QuestionNumber
Acceptable Answers Reject Mark
18 (b)(i) Reagent – Hydrogen/H2 (1) Catalyst –Nickel/Ni/palladium/Pd/platinum/Pt (1)
Mark independently
2
QuestionNumber
Acceptable Answers Reject Mark
18 (b)(ii) 1,2 – dibromoethane (1)
ignore punctuation
H
H H
C C H
Br Br (1)
Mark independentlyAllow CH2BrCH2Br
1,2 - bromoethanedibromoethane
Skeletal formula
C2H4Br2
2
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QuestionNumber
Acceptable Answers Reject Mark
18 (b)(iii) From purple / pink " colourless clear 1
QuestionNumber
Acceptable Answers Reject Mark
18 (c)(i)
arrow from bromide ion can start from any part of thebromide ion and can go towards the C or the + sign onthe intermediate
bromide ion must show negative charge
allow 2 max for addition of Br2 and any otherelectrophilic additions
half headed arrows used throughout penalise only once
#- onbromide
ion forthirdmark
3
QuestionNumber
Acceptable Answers Reject Mark
18 (c)(ii) Bromine / bromide / hydrogen could add toeither carbon (in the double bond)/ bromide / bromine could add to eitherprimary or secondary carbocation/ (propene is unsymmetrical) so could form1-bromopropane and / or 2-bromopropane.
Allow correct structural or displayed formulae.
bromine couldadd to any of the threecarbons
1
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QuestionNumber
Acceptable Answers Reject Mark
18 (d)
C C C
H
H H
C
H H
C6H5 H C6H5
position of hydrogen atoms and phenyl groups(1)
Allow phenyl groups on 2nd and 3rd carbon OR1st and 4th OR 1st and 3rd
carbon carbon single bonds and continuation
bonds (1)
second mark not awarded for incorrectmonomer
(1) max with or without square brackets and nor numbers
Do not penalise H from phenyl groups attachingto carbon chains
Ignore extra square brackets, numbers and ‘n’provided 2 monomer units shown
2
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QuestionNumber
Acceptable Answers Reject Mark
18 (e)(i) Any two
(raw material for) paper cup requires cutting downtrees (1)
polystyrene cup uses less energy (280 kWh ratherthan 980 kWh) to produce so less CO2 released / lessfossil fuels (1)
polystyrene cup releases less sulfur based compoundsinto air so less chance of forming acid rain / lesschance of damaging buildings / acidifying lakes(produces 3.5 kg rather than 11 kg) (1)
polystyrene cup releases no chlorine compoundswhich damages ozone layer / poisonous (produce 0kg rather than 0.4 kg) (1)
2 pieces of data chosen with no explanation allow 1mark
Ignore comments regarding water
2
Question
Number
Acceptable Answers Reject Mark
18 (e)(ii) 2 additional factors
e.g ease of recyclabilitywhether cup is easy to reusespace taken up in landfilltype and amount of gases formed if incinerateduseful heat obtained if incineratedbiodegradeability / how long they take to decomposemanagement of gases produced during
decompositiondurability / how long the cup lastsmethod of disposal
Ignore comments regarding atom economy
Ignore comments regarding acid rain / ozone layer /greenhouse gases unless linked to gases producedduring disposal
2
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Further copies of this publication are available fromEdexcel Publications, Adamsway, Mansfield, Notts, NG18 4FN
Telephone 01623 467467Fax 01623 450481
Email [email protected]
Order Code US023629 Summer 2010
For more information on Edexcel qualifications, please visit www.edexcel.com/quals
Edexcel Limited. Registered in England and Wales no.4496750Registered Office: One90 High Holborn, London, WC1V 7BH
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Mark Scheme (Results)
June 2010
GCE
GCE Chemistry (6CH02/01)
Edexcel Limited. Registered in England and Wales No. 4496750Registered Office: One90 High Holborn, London WC1V 7BH
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Edexcel is one of the leading examining and awarding bodies in the UK and throughout theworld. We provide a wide range of qualifications including academic, vocational,occupational and specific programmes for employers.
Through a network of UK and overseas offices, Edexcel’s centres receive the support theyneed to help them deliver their education and training programmes to learners.
For further information, please call our GCE line on 0844 576 0025, our GCSE team on 0844576 0027, or visit our website at www.edexcel.com.
If you have any subject specific questions about the content of this Mark Scheme thatrequire the help of a subject specialist, you may find our Ask The Expert email servicehelpful.
Ask The Expert can be accessed online at the following link:
http://www.edexcel.com/Aboutus/contact-us/
Alternatively, you can speak directly to a subject specialist at Edexcel on our dedicatedScience telephone line: 0844 576 0037
Summer 2010
Publications Code US023632
All the material in this publication is copyright© Edexcel Ltd 2010
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Section A (multiple choice)
QuestionNumber
Correct Answer Mark
1(a) D 1
QuestionNumber
Correct Answer Mark
1(b) A 1
QuestionNumber
Correct Answer Mark
1(c) B 1
QuestionNumber
Correct Answer Mark
2 D 1
QuestionNumber
Correct Answer Mark
3 C 1
QuestionNumber
Correct Answer Mark
4 C 1
QuestionNumber
Correct Answer Mark
5 B 1
QuestionNumber
Correct Answer Mark
6 D 1
QuestionNumber
Correct Answer Mark
7 D 1
QuestionNumber
Correct Answer Mark
8 B 1
QuestionNumber
Correct Answer Mark
9 C 1
QuestionNumber
Correct Answer Mark
10 A 1
Question
Number
Correct Answer Mark
11 A 1
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QuestionNumber
Correct Answer Mark
12 A 1
QuestionNumber
Correct Answer Mark
13 D 1
QuestionNumber
Correct Answer Mark
14 D 1
QuestionNumber
Correct Answer Mark
15 B 1
QuestionNumber
Correct Answer Mark
16 A 1
QuestionNumber
Correct Answer Mark
17 A 1
QuestionNumber
Correct Answer Mark
18 B 1
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Section B
QuestionNumber
Acceptable Answers Reject Mark
19 (a) Mark independently
From: colourless (1)To: pink / (pale) red (1)
If colour change wrong way round max (1)
From: clearTo: magenta /purple / cerise
2
QuestionNumber
Acceptable Answers Reject Mark
19 (b) (Titres 2, 3 and 4) are concordant / within
0.2 (cm3) / within 0.1 (cm3) / consistentOR Titre 1 is rough / trial / a rangefinder / too farout / overshot
ALLOW Titre 1 is an outlier / is anomalous
Just “very
similar” /within 0.05 /within 0.5
Titre 1 “verydifferent”
Just “notaccurate”
“Titration 1 isa controlexperiment”
1
QuestionNumber
Acceptable Answers Reject Mark
19 (c) 28.00 (cm3) / 28.0 (cm3) / 28 (cm3) 28.14 (cm3) /28.1 (cm3) /28.13 (cm3)
1
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IN (d)(i) to (d)(v), IGNORE UNITS EVEN IF INCORRECT ANDALLOW ANSWER IN EACH CASE WHETHER BY TE OR MARK SCHEME ANSWER, REGARDLESS OF
ANY WORKING SHOWN
QuestionNumber
Acceptable Answers Reject Mark
19 (d)(i) 0.100 x 28.00 = 0.0028 / 2.8 x 10 (mol)-3
1000
ALLOW TE from (c)
IGNORE sf except one sf
1
QuestionNumber
Acceptable Answers Reject Mark
19 (d)(ii) 0.0028 / 2.8 x 10-3
(mol)
OR
Same answer to (d)(i) if TE applied
IGNORE sf except one sf
1
QuestionNumber
Acceptable Answers Reject Mark
19 (d)(iii) 0.0028 = 0.112 (mol dm-3)0.025
OR
Answer to (d)(ii) if TE applied from (d)(ii)0.025
IGNORE sf except one sf
1
QuestionNumber
Acceptable Answers Reject Mark
19 (d)(iv) 10 x 0.112 = 1.12 (mol dm-3)
OR
Answer to (d)(iii) x 10 if TE applied from(d)(iii)
IGNORE sf except one sf
1
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QuestionNumber
Acceptable Answers Reject Mark
19 (d)(v) 1.12 x 60 = 67.2 (g dm-3)
OR Answer to (d)(iv) x 60 if TE applied from(d)(iv)
IGNORE sf except one sf
67.1 1
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QuestionNumber
Acceptable Answers Reject Mark
19 (e) NOTE : answer must refer to making up thediluted solution and not the titration
NOTE : the Reason mark must be correctlylinked to the Improvement
Improvement:Use a pipette / burette to measure acid(solution) (1)
Reason:Pipette / burette more accurate (than ameasuring cylinder) (1)
ALLOW “more precise”
OR Improvement:Shake / invert the volumetric flask (thoroughly) (1)
Reason:To ensure a uniform concentration (1)
OR Improvement: Rinse out measuring cylinder (and transferwashings to the volumetric flask) (1)
Reason: To ensure all the acid is transferred (to the
volumetric flask) (1)
OR Improvement:Use a (teat) pipette to make up to the mark (involumetric flask) (1)
Reason:To ensure volume of solution accuratelymeasured (1)
Use of volumetricflask for initial measurementof volume of vinegarsolution
“morereliable”
swirl (theflask)
to ensure“fullydissolved”
just “rinse outapparatus”
Any suggestedimprovementsrelating to thetitration part
of thisexperiment
2
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QuestionNumber
Acceptable Answers Reject Mark
19 (f)(i) Z / between 27.85 and 28.05 (cm3)
ALLOW 27.95 ±0.10 (cm3)
1
QuestionNumber
Acceptable Answers Reject Mark
19 (f)(ii) Any one of the following / a statementequivalent to:
! overshoots/misses end-point
! water left in burette / pipette! air lock below tap in burette / air in
pipette
! burette not vertical
! alkali not at stated concentration
! leaking tap
! not reading meniscus at eye-level
! funnel left in top of burette
! not reading level against a whitebackground
! not reading meniscus correctly
! washing pipette between titres! washing the flask with the solution that
will go in it
! not swirling flask / mixture
IGNORE “errors in calculation”
“water left inconical flask”
just“measurementsmay beinaccurate”
“there could beuncertaintywith otherequipment”
“contaminationof the vinegar”
1
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QuestionNumber
Acceptable Answers Mark
20 (a)(i)H C
H3C
C H
H
H
Br
H C
H3C
C H
H
H
Br(:)
H
H3C
C H
H
H
C
Br
(1) for both arrows
(1) for carbocation
(1) for arrow
1st mark:
! top arrow must start from the double bond / close to thedouble bond and not from either of the C atoms of theC=C bond
! top arrow can end on, or close to, the H in HBr
! lower arrow must start from the bond and not the Hatom in HBr
REJECT full charges on the HBr
2nd mark:the carbocation must have a full + and not !+
3rd mark:
! the bromide ion must have a full — and not !— ! the lone pair need not be shown on the Br—
! arrow from bromide ion can start anywhere on the Br–— orfrom the minus sign or the lone pair (if shown) on Br— andcan go to the C or the + sign on the intermediate
3rd mark available even if an incorrect intermediate has beendrawn
3
QuestionNumber
Acceptable Answers Reject Mark
20(a)(ii)
H C
H3C
C H
H
H
OR
CH3 CH2 CH2+
1
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QuestionNumber
Acceptable Answers Reject Mark
20(b)(i) B /CH3CH2CH(OH)CH3 /butan-2-ol (1)
Because the C atom bearing the OH is attachedto two other C atoms / C with OH groupattached to one H (atom) (1)
ALLOW Because the C atom bearing the OH isattached to two alkyl groups
These marks are stand alone
Just “OH is onthe second Catom” / “OHis in the chain,not on theend”OR“OH attachedto two methyl / two CH3 groups”
OH- (instead of –OH)
2
QuestionNumber
Acceptable Answers Reject Mark
20(b)(ii) C /(CH3)3COH /(2-)methylpropan-2-ol (1)
Because it is a tertiary (alcohol)/no C-H bondsto break (1)
ACCEPT a description of a tertiary alcohol
These marks are stand alone
“tertiarystructure” /
“tertiarycarbon” /“tertiarycarbocation”
2
QuestionNumber
Acceptable Answers Reject Mark
20(b)(iii) BOTH
B / CH3CH2CH(OH)CH3 / butan-2-ol
AND
H
H H O H
H
HHH
C C C C
BOTH required for the one mark
Structural /skeletalformula
1
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QuestionNumber
Acceptable Answers Reject Mark
20(b)(iv) A / CH3CH2CH2CH2OH / butan-1-oland
D / CH3CH(CH3)CH2OH / (2-)methylpropan-1-ol
BOTH needed for one mark
1
QuestionNumber
Acceptable Answers Reject Mark
20(b)(v) Steamy fumes / misty fumes / white mist White smoke 1
QuestionNumber
Acceptable Answers Reject Mark
20(b)(vi) (C4H9OH + PCl5 !) C4H9Cl + POCl3 + HCl
(1) for HCl(1) for rest of the equation correct
NOTE: Equation must be completely correct forthe second mark.
ACCEPT “PCl3O” instead of POCl3
2
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QuestionNumber
Acceptable Answers Reject Mark
21(a)(i) Mark the two points independently, subjectto the constraint in Reject column
Effect:(Equilibrium) shifts to the right (1)
ALLOW: “favours forward reaction” / “increasethe amount of product” / “increase the yield(of product)”
Reason:Exothermic (in forward direction) (1)
NOTE: Just “(equilibrium) shifts in theexothermic direction” scores (1)
“Equilibriumshifts to left”will score (0)for (a)(i)
2
QuestionNumber
Acceptable Answers Reject Mark
21(a)(ii) First mark:Activation energy for the reaction is too high /(if cooled) molecules would not have enoughenergy to react / few(er) molecules have the
required E a/more molecules have energy "
E
aat higher temperaturesOR not (technologically) feasible to cool the gasesbefore they enter the converter/costly to coolthe gases
(1)
Second mark:(cooling the gases would make) the rate (too)slow /rate is faster if the temperature is high(so the gases are not cooled)
(1)
Cooling thegases
decreases theyield (of products) /anincorrect LeChatelierargument
2
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QuestionNumber
Acceptable Answers Reject Mark
21(a)(iii) Mark the two points independently, subjectto the constraint in Reject column
Effect:(Equilibrium) shifts to the right
ALLOW: “favours forward reaction” / “increasethe amount of product” / “increase the yield of product”
(1)
Reason:Shifts / moves in the direction of fewer (moles
of gas) molecules
ALLOW “shifts in direction of fewer moles (of gas molecules)”
(1)
IGNORE effect on the rate
“Equilibriumshifts to left”will score (0)for (a)(iii)
“.... fewer
atoms”
2
QuestionNumber
Acceptable Answers Reject Mark
21(b)(i) (In NO): +2 / 2+ (1)
(In NO3–): +5 / 5+ (1)
NOTE:
(In NO): Just “2”AND(In NO3
–): Just “5” scores (1)
2
QuestionNumber Acceptable Answers Reject Mark
21(b)(ii) NO3— + 4H+ + 3e— ! NO + 2H2O
ACCEPT multiples
1
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QuestionNumber
Acceptable Answers Reject Mark
21(b)(iii) Ag ! Ag+ + e(—) / Ag – e(—)! Ag+
ACCEPT multiplesIGNORE state symbols, even if incorrect
“Ag + e— ! Ag+”
1
QuestionNumber
Acceptable Answers Reject Mark
21(b)(iv) 3Ag + NO3— + 4H+ ! 3Ag+ + NO + 2H2O
(2)
(1) for multiplication of the silver half-equation
by three or cq multiple from (b)(ii)
(1) for rest of equation correctNOTE: Equation must be completely correct forthe second mark.
IGNORE state symbols, even if incorrect
if any e— areleft in thefinal equation,second markcannot bescored
2
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SECTION C
QuestionNumber
Acceptable Answers Reject Mark
22(a)(i) 2-bromo-2-chloro-1,1,1-trifluoroethane
ALLOW
1-bromo-1-chloro-2,2,2-trifluoroethane
IGNORE incorrect punctuation and incorrectorder of the halogen atoms
“1-bromo-1-chloro-2-trifluoroethane”
1
QuestionNumber
Acceptable Answers Reject Mark
22(a)(ii) London (forces) / instantaneous dipole /induced dipole / dispersion / van der Waals’(forces) (1)
permanent dipole (-permanent dipole) (forces)/ dipole-dipole (forces) / dipole (forces) (1)
IGNORE any references to hydrogen bonding
2
QuestionNumber
Acceptable Answers Reject Mark
22(a)(iii) Any one of the following / a statementequivalent to:
Ethanol is flammable[Note: if any reference to only thehalogenoalkane being flammable scores (0)]ORreference to greater control of heating (e.g.“to control the rate of reaction” / “to preventthe reaction being too vigorous” / “to prevent
the reaction getting out of control”) ALLOW “so that the reaction takes placeslowly”OR“(reaction) mixture is flammable/it isflammable”OR“Bunsen flame too hot / too vigorous”OR“(Bunsen flame) would cause too muchevaporation to occur”OR
“(allows) constant heating”/ “even heating”
Compound X isflammable
Just “toprevent anexplosion”
Just “tominimise therisk”
1
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QuestionNumber
Acceptable Answers Reject Mark
22(a)(iv) Solvent (for both reactants)ORTo dissolve (the reactants)ORTo mix the reactants
ALLOW “To enable the mixture to dissolve”
Just “mixing”
“to acidify thesilver nitrate”
1
QuestionNumber
Acceptable Answers Reject Mark
22(a)(v) Cream / off-white / pale-yellowprecipitate
ALLOW Cream / off-white / pale-yellow solidIGNORE incorrect identification of thisprecipitateNOTE: both colour and state (of the AgBr)needed
Just“Yellow”(precipitate/solid)OR“whiteprecipitate”OR“white-yellowprecipitate”
(0) if
contradictoryobservationgiven, eg“creamprecipitateand fizzing”
1
QuestionNumber
Acceptable Answers Reject Mark
22(a)(vi) Ag+(aq) + Br— (aq) ! AgBr(s)
Must include state symbols ACCEPT multiples
If NO3
—
left oneither side
1
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QuestionNumber
Acceptable Answers Reject Mark
22(b)(i) Mark independently
Name: ethanol (1) ALLOW “ethan-1-ol”
Structural formula: CH3CH2OH or C2H5OH (1) Allow displayed formula ALLOW brackets around the OH
C2H6O
2
QuestionNumber
Acceptable Answers Reject Mark
22(b)(ii) Mark independently
1st mark:Energy of products, labelled, below that of reactants, labelled (1)
Note if the words ‘reactants’ and ‘products’are written, ignore any formulae
Note if the words ‘reactants’ and ‘products’are not written, both formulae of the reactants
and both formulae of the products must begiven. (Na+ ions can be omitted.)
2nd mark:Shape of profile with one ‘hump’ (1)
3rd mark:Activation energy / “E a” correctly shown with asingle-headed arrow to the peak (or close toit) (1)
Maxwell-Boltzmanncurve scores(0) for (b)(ii)
Double-headed arrowshowing E a
3
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QuestionNumber
Acceptable Answers Reject Mark
22(c)(i) Chlorofluorocarbon
Accept ..flouro… spelling
1
QuestionNumber
Acceptable Answers Reject Mark
22(c)(ii) Any one of the following / a statementequivalent to:
aerosol / propellant / spray cansOR (degreasing) solvent
OR fire retardant
ALLOW fire extinguishers / putting out fires ALLOW making expanded polystyrene / makingplastics / making polymers
pesticides /anaesthetics
just“retardant”
anti-freeze
air-conditioning
frying pans
detergents
1
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QuestionNumber
Acceptable Answers Reject Mark
22(c)(iii)QWC
Mark independently
1st mark:
O + O3 " 2O2 IGNORE any state symbols (1)
2nd mark:(chlorine free radical acts as a) catalyst (1)
Last 3 marks:any three from:
! (the chlorine free radical) persists inthe atmosphere / continues to attack /is regenerated / (starts) a chainreaction (1)
NOTE ‘chain reaction’ may be described interms of a chlorine radical breaking down many/ a large number of / a specified number of, eg10,000, O3 (molecules).NOTE: As written, this response also earns the
scoring point relating to ozone depletion.
! less ozone / ozone decreases / causeshole(s) in ozone layer / breakdown of ozone (layer) / damages ozone layer /depletes ozone layer (1)
! UV (reaching Earth’s surface) increases/ less UV absorbed / (more) UV reachesEarth’s surface (1)
! causes (skin) cancer/mutation / DNAdamage occurs (1)
IGNORE any references to “global warming” /“Greenhouse Effect”
If Cl# and / orClO# left inequation
OR
2O3 " 3O2
Just (UV)“harmful”
5
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QuestionNumber
Acceptable Answers Reject Mark
22(d)(i) The C-F bond is (very) strongORC-F bond is (much) harder to break than theC-Cl bond
OR
UV/radiation does not have enough energy/does not have (high) enough frequency
Any mention of electronegativityOR mention of bondpolarity scores(0)
1
Question
Number
Acceptable Answers Reject Mark
22(d)(ii)QWC
(long wavelength) IR /infrared radiation (1)
The molecule is polarOR(the molecule) changes its polarityOR“polar bonds”ORvibrational energy/vibrations of the bonds /
stretching or bending increasesOR(IR causes) bonds to vibrate
(1)
Marks are stand alone
UV /ultraviolet
Just“moleculevibrates” (0)
2
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Further copies of this publication are available fromEdexcel Publications, Adamsway, Mansfield, Notts, NG18 4FN
Telephone 01623 467467Fax 01623 450481
Email [email protected]
Order Code US023632 Summer 2010
For more information on Edexcel qualifications, please visit www.edexcel.com/quals
Edexcel Limited. Registered in England and Wales no.4496750Registered Office: One90 High Holborn, London, WC1V 7BH
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Mark Scheme (Results)June 2010
GCE
GCE Chemistry (6CH07/01)
Edexcel Limited. Registered in England and Wales No. 4496750Registered Office: One90 High Holborn, London WC1V 7BH
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Edexcel is one of the leading examining and awarding bodies in the UK and throughout theworld. We provide a wide range of qualifications including academic, vocational,occupational and specific programmes for employers.
Through a network of UK and overseas offices, Edexcel’s centres receive the support theyneed to help them deliver their education and training programmes to learners.
For further information, please call our GCE line on 0844 576 0025, our GCSE team on 0844576 0027, or visit our website at www.edexcel.com.
If you have any subject specific questions about the content of this Mark Scheme thatrequire the help of a subject specialist, you may find our Ask The Expert email servicehelpful.
Ask The Expert can be accessed online at the following link:
http://www.edexcel.com/Aboutus/contact-us/
Alternatively, you can speak directly to a subject specialist at Edexcel on our dedicatedScience telephone line: 0844 576 0037
Summer 2010
Publications Code US023643
All the material in this publication is copyright© Edexcel Ltd 2010
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Qu ties on Acceptable Answers Re tjecNumber
Mark
1 (a)(i Nichrome wire / platinum wire / ceramic / silicarod (1)
Accept recognisable spelling eg platinium,nickrome
(Co eacid H / solution (1)
Salt (mixed with wire and acid, and) placed in aho l nsenbur r
Titanium,aluminium,
nickel,chromium,cosilicon
Salt plBunsen burnerOR flaaloit
3)
nc ntrated /dilute) hydrochloric/ Cl/HCl(aq)
t/b ue/roaring/non-luminous/Bunsen/Bune flame (1)
pper,
aced in
mene OR burn
QuestionNumber
Acceptable Answers Re tjec Mark
1 (a)(ii) Li+
Accept li+/ Li+ ions/ A is Li+
Ignore (aq), (s), (l), (g)
Li, Li2+ RbCa2+, SLit mlith m
1,Ca, Sr,
r2+, Rb+
hiu /iu ions
QuestionNumber
Acceptable Answers Reject Mark
1 ( Cal u 2 / slaked lime
Accept calcium oxide/CaO / quicklime
Ignore (aq) / solution / (s) / solid
Cal u CO2/CaCO3
1b)(i) ci m hydroxide/Ca(OH) ci m/Ca
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QuestionNu e
Acceptable Answers Re tjecmb r
Mark
1 (b)(i CO /
Ignore separated additional cation
Carbon dioxide gas given off (when thiscarbonate /hydrogencarbonate isheated/decomposed) (1)
Second mark depends on a recognisablecarbonate/hydrogencarbonate ie CO3, CO3
-,carbonate, hydrogencarbonate
Li2CO3, LiHCO3, CaCO3 etc
CO C 3 ,
car nhyd ognateLi2 3 LiHCO3,
CaCO3 etc
2i) 32- HCO3
- (1) 3, O -
bo ate,r encarbo
CO ,
QuestionNumber
Acceptable Answers Reject Mark
1 (c)(i) Oxide / O2- Oxygen, O2, O,O-
calcium oxide/ CaO
1
QuestionNumber
Acceptable Answers Reject Mark
1 (c)(ii) Hydroxide / OH-/(OH-)2
(OH)2
- 1
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Qu ties on Acceptable Answers Re tjecNumber
Mark
1 (c)(i Mark with reference to (ii)
For correct answer to (ii)
Un r er) (1) TuAccept other appropriate indicatorseg (red) litmus (paper) turns blueORAdd a suitable metal ion solution (1) to e[seOR
Wa s (1) Alkalineblu aOROth reg Titrate with hydrochloric acid and suitableind r
If incorrect answer to (ii) but answer as above(1) a If incorrect answer to (ii) with correct test and
correct result for that ion (1) max
2ii)
ive sal indicator (paprns blue/purple/pH12-14 (1)
giv a correct colour of precipitate (1)e User Guide 2 page 17 for some details]
/ heat with ammonium ionrmgas given off/damp red litmus turns
e/ mmonia gas given off (1)
reasonable tests with resultse
icator with correct final colou
m x
QuestionNu e
Acceptable Answers Re tjecmb r
Mark
1 (d) Li2CO3 Accept Li2(CO3)ORLiHCO3
Accept correct formula of any red flame
coloured s block metalca n teeg Rb2CO3, CaCO3, SrCO3
LiCO3
1
rbo ate/hydrogencarbona
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Qu ties on Acceptable Answers Re tjecNumber
Mark
2 (a)(i Silver((I))iodide (solid / precipitate) / AgI / Ag+I-
/AgI(s)
OR Silver((I))iodide (solid / precipitate) and AgI /Ag /
Iodide (alone)
IodineSilver ((I))iodineAgBr and AgICl-/Br-/I-
If both nameand formulaare given andeither is wrongeg Silver((I))Iodine and AgI
1)
+ -I AgI(s)
QuestionNumber
Acceptable Answers Reject Mark
2 (a)(ii) C3H n any order)
Acformu
Any answerwhich does nothave C3H7Isomewhere
17I (i
cept additional information like additionallae
QuestionNumber
Acceptable Answers Reject Mark
2 (a)(iii) H| |
H- C C -H|
H
Accept structural formula CH3CHICH3
Displayed orstructuralformula for 1-iodopropane
1H H|
C – –| |
I H
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QuestionNumber
Acceptable Answers Reject Mark
2 (a)(iv) At first ignore answer to (iii)
Propan-2-ol / 2-propanol / CH3CH(OH)CH3
Accept displayed formula (allow slightlydisplaced bonds C)
|HO
Accept skeletal formula
Allow TE from (a)(iii)eg 1-iodopropane forms propan-1-ol
Propanolprop-1-olC3H7OH
1
QuestionNumber
Acceptable Answers Reject Mark
2 (b)(i) Mark colours independently
From orange (1)
To green/blue (1)
Accept shades of green eg dark green, muddygreen, green-brown
yellow
2
QuestionNumber
Acceptable Answers Reject Mark
2 (b)(ii) Propanone
Accept propan-2-one
Allow propanal/propanoic acid if TE from (a)(iv)
prop((-2-))one 1
QuestionNumber
Acceptable Answers Reject Mark
2 (b)(iii) Oxidation / redox / oxidation and reduction/ oxidation of … (eg alcohol)
ReductionCondensation/substitution/Addition
1
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Qu ties on Acceptable Answers Re tjecNumber
Mark
3 (a)(i (Glass/graduated/volumetric/bulb)pipette (and
pipette filler)
Accept any recognisable spelling of pipetteeg pipet, pipette etc
Burette/
pipette andburette/measuringcylteat pdro ipip t Pipate/pipotte
1)
inder/ipette/
pp nget e
QuestionNumber
Acceptable Answers Rej cte Mark
3 (a)(ii) Starch (solution) (1)
Accept startch
Blue-black/blue/black to colourless (1)
Accept purple/blue-black to colourless
Second mark depends on first
OtherindicaMethy/phenthalein
Colourblue-black/black
2tors egl orangeolph-
less to
blue/
QuestionNu emb r
Acceptable Answers Reject Mark
3 (b)(i 14.5(0), 13.7(0), 13.75All three needed for the mark
1)
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QuestionNumber
Acceptable Answers Reject Mark
3 (b)(i The first result is discarded/ ignored/ not
included/a range finder
OROnly use last two valuesORTh e rd are concordant / firstvalue not within 0.2 cm3
Accept:ThORActual correct average calculation to give
13.73/13.725
1i)
e s cond and thi
is is the average of the second and third runs
QuestionNumber
Acceptable Answers Reject Mark
3 (b)(iii) 13.73 x 0.0200 = 2.746 x 10-4 /0.0002746(mol)1000
Accept 2.7/2.75 x 10-4
Note that 13.725 gives 2.745 x 10-4
Allow TE from different calculated average titre
1 sf 1
QuestionNumber
Acceptable Answers Reject Mark
3 (c) 1.373 x10-4 /0.0001373(mol)
Also 1.35/1.37/1.375 /1.4 x 10-4
Accept answer to (b)(iii)2
1 sf (unlessalreadypenalisedanywhere in
this question)
1
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Qu ties on Acceptable Answers Re tjecNumber
Mark
3 (d) 4.58 x 10-5 /0.0000458(mol)
4.57667/4.577 x 10-5 etc
Als Ac
o 4.583/4.57/4.6(0) x 10-5
cept answer to (c)3
1 sf (unless
alreadypenalisedan h re inthis question)
1
yw e
QuestionNumber
Acceptable Answers Re tjec Mark
3 (e)(i) Vo
(100 cm3)roundbottomedflask/conical flask/measuringcylinder
1lumetric/graduated (flask)
QuestionNumber
Acceptable Answers Reject Mark
3 (e)(i These marks are independent of flask used in (i)
Tra f ings (1)
Ma u Mix g is must be at theend) (
Make sure it isall transferred
3i)
ns er solution and rinsings/wash
ke p to the mark (1)
in / inverting / shaking (th1)
Question
Number
Acceptable Answers Reject Mark
3 (e (i 4.58 x 10 Also 4.57/4.6 x 10-4
Accept Answer to (d) x 10
1 sf (unlesalreadypenalisedanywhere inthis question)
1) ii) -4 /0.000458 (mol) s
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QuestionNumber
Acceptable Answers Reject Mark
3 (e)(i 4.58 x 10 x 214
= 0.098 /0.98012 g
Also 0.097941/0.0979 etc
Accept answer to (e)(iii) x 214Ign e
1 sf (unless
alreadypenalisedanywhere inthis question)
1v) -4
or SF
QuestionNumber
Acceptable Answers Reject Mark
3 (e)(v) 0.098 x 100
0.10= 98 /98.0/98.01/98.012 %
Also 97.941/97.94/97.9 %
Accept answer to(e)(iii) x1000.10
correct answer with no working scores (1) Ignore SF
1 s u
alreadypenalisedanywhere inthis question)
1f ( nless
QuestionNumber
Acceptable Answers Reject Mark
3 (f) Sulfuric acid is corrosive/irritant/irritable/burns(skin)
Sulfuric acid isharmful/hazardous/toxic
1
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Qu ties on Acceptable Answers Re tjecNumber
Mark
4 (a)(i From the equation 1 mol butan-1-ol gives
1 mol of 1-bromobutane / ratio 1:1 OWTTE (1) As 80% yield, 0.125 mol of butan-1-ol gives 0.125x 0.8 mol = 0.1 mol of 1-brombutane (1)
Accep that they appreciatethe proportion calculation and the mole ratio
Examples:
Number of moles of butan-1-ol = 0.1 x 100
)
t any clear indication
/ 0.180 0.8
(= 0.125)
OR Nu e butane
= 80mb r of moles of 1-bromo
x 0.125100
(= 0.1)
In both these examples ‘butan-1-ol’/‘1-bromobutane’ as appropriate, must bepresent to g
The numerical expression alone would gain (1)
OR
As above examples but additionally using molarmasses to calculate masses
2
ain (2)
QuestionNumber
Acceptable Answers Reject Mark
4 (a)(ii) 74 x 0.125 (1) = 9.25 g)
9.
(
25 = 1.4 /11.42/11.420/11.419753 cm (1) 0.81
ie o Accept 11.4 /11.42/11.420/11.419753 cm3 (2) (with no working)
1sf
2
1 3
ign re sf unless only one
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QuestionNumber
Acceptable Answers Reject Mark
4 (a)(iii) 0.125 x 119 = 14.875 /14.87/14.88/14.9/15 (g) 1 s 1f
QuestionNumber
Acceptable Answers Reject Mark
4 (b) Flask in beaker of labelled cold water (1)Water need not be drawn in but…
Condenser with jacket (1)Need not be labelled, can be at any angle solong as it goes upwards
Condenser inlet and outlet with correct waterdirection (1)This mark can be given if no jacket is present
open at top and no leaks(1)This mark is conditional on a condenser
Do not penalise accidental closures in drawingor attempts to draw out perimeter of apparatusmaking the condenser appear closed
If distillation set up is drawn the beaker of coldwater mark can be awarded
heated beaker(of cold water)
stopper in thetop/tap funnelin the top of the condenserunless clearlyopen
4
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Qu ties on Acceptable Answers Re tjecNumber
Mark
4 (c)(i Lower layer as more dense
Lower layer is 1-bromobutane because it isdenser Lower r / butan-1-ol
1)
layer as denser than wate
QuestionNumber
Acceptable Answers Reject Mark
4 (c)(ii) To r mhydrochl acid/H2SO4
(1) by a
2e ove / neutralize / react with remainingoric acid/HCl/acid/sulfuric
re cting to form carbon dioxide (gas) (1)
QuestionNumber
Acceptable Answers Reject Mark
4 (d Distillation /fractional dist /distil/d l
Accept any recognisable spelling
Ignore further description
Allow a description which includes the wordshe n
Dry/filter/an i
1)(i) illation /redistil
isti late
ati g / boiling followed by condensing
oryth ng else
QuestionNumber
Acceptable Answers Reject Mark
4 (d)(ii) Me
compare with Data Book value (101.7 oC)(Pu
ORBoils at boiling temperature of liquid/101.7 o small temperaturerange/ boils at one part ORCollect the product at 101.7 oC/ between 100and 103 oC
1asure boiling temperature of liquid {and
re if it agrees)}
C / boils over a veryicular temperature
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Further copies of this publication are available fromEdexcel Publications, Adamsway, Mansfield, Notts, NG18 4FN
Telephone 01623 467467Fax 01623 450481
Email [email protected]
Order Code US023643 Summer 2010
For more information on Edexcel qualifications, please visit www.edexcel.com/quals
Edexcel Limited. Registered in England and Wales no.4496750Registered Office: One90 High Holborn, London, WC1V 7BH
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Mark Scheme (Results)
June 2010
GCE
GCE Chemistry (6CH04/01)
Edexcel Limited. Registered in England and Wales No. 4496750Registered Office: One90 High Holborn, London WC1V 7BH
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Section A (multiple choice)
QuestionNumber
Correct Answer Mark
1 (a) D 1
QuestionNumber
Correct Answer Mark
1 (b) D 1
QuestionNumber
Correct Answer Mark
1 (c) A 1
QuestionNumber
Correct Answer Mark
2 B 1
QuestionNumber
Correct Answer Mark
3 C 1
QuestionNumber
Correct Answer Mark
4 D 1
Question
Number
Correct Answer Mark
5 B 1
QuestionNumber
Correct Answer Mark
6 A 1
QuestionNumber
Correct Answer Mark
7 (a) C 1
QuestionNumber Correct Answer Mark
7 (b) B 1
QuestionNumber
Correct Answer Mark
7 (c) D 1
QuestionNumber
Correct Answer Mark
8 B 1
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QuestionNumber
Correct Answer Mark
9 D 1
Question
Number
Correct Answer Mark
10 D 1
QuestionNumber
Correct Answer Mark
11 B 1
QuestionNumber
Correct Answer Mark
12 A 1
Question
Number
Correct Answer Mark
13 B 1
QuestionNumber
Correct Answer Mark
14 C 1
QuestionNumber
Correct Answer Mark
15 C 1
QuestionNumber
Correct Answer Mark
16 A 1
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Section B
QuestionNumber
Acceptable Answers Reject Mark
17 (a)(i) 5.7 x 10 –5 /5.71 x 10 –5 /5.714x 10 –5 /0.000057
IGNORE SF except 1 (ie don’t accept 6 x 10 –5)
1
QuestionNumber
Acceptable Answers Reject Mark
17 (a)(ii) C4H9Br: first order / 1 (1)
(going from first to second experiment)rate doubles when concentration / number of
moles doubles (and [OH—
] constant )/ rate andconcentration increase in proportion (1) ALLOW ‘time halves’ instead of ‘rate doubles’
OH— : zero order / 0and(going from second to third expt) as increase inconcentration does not affect rate (and[C4H9Br] constant ) (1)
ALLOW ‘doubling in concentration of OH—
instead of ‘increase in concentration’
ALLOW time increases by the same factor asincrease in hydroxide concentration (5/3)
May refer to experiment number rather thanconcentrations
3
QuestionNumber
Acceptable Answers Reject Mark
17 (a)(iii) Rate = k[C4H9Br]OR Rate = k[C4H9Br]1[OH—]0
ALLOW k in lower or upper case
Rate equation must be consistent with orders in(a)(ii)If no order is given for hydroxide in (ii) markcannot be given
1
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Acceptable Answers Reject Mark
17 (a)(iv) k= 2.9 x 10-5 0.017
= 1.7 x 10-3 / 1.71 x 10-3 / 1.706 x 10-3 s-1
ALLOW k=1.68 x 10-3
(value obtained from experiment 2 or 3)
value of k (1)
units (1) stand alone mark
ALLOW TE from (a)(iii)IGNORE SF except 1
Rate = k[C4H9Br]2 gives k= 0.10036 dm3 mol-1s-1
Rate = k[C4H9Br][OH-] gives k= 1.42 dm3 mol-1s-1
ALLOW k=1.39 dm3 mol-1s-1
(value obtained from experiment 2 or 3)
Rate = k[C4H9Br][OH-]2 gives k= 1184.6dm6 mol-2s-1
Rate = k[C4H9Br]2[OH-] gives k= 83.62dm6 mol-2s-1
2
QuestionNumber
Acceptable Answers Reject Mark
17(b) [OH—] is (in chemical equation but) not in rateequation / not in rate determining step (so is ina step other than rate determining step)
OR
Only C4H9Br is in rate equation / ratedetermining step (so OH— is in a step other thanrate determining step)
1
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QuestionNumber
Acceptable Answers Mark
17 (c)First markChoice of bromoalkane must be consistent with rate equation in(a)(iii).If [OH—] is not in rate equation, secondary/tertiarybromoalkane.If [OH—] is in rate equation, primary/secondary bromoalkane. (1)
Second and third marks
Either SN1 or SN2 mechanism can score 2 marks regardless of choice of bromoalkane.
Lone pairs not required
Curly arrow from C-Br bond to Br (making Br—) (1)
Curly arrow from anywhere on OH— / HO— to C+ in correctintermediate (making alcohol) (1)
OR
Both curly arrows from OH— and from C-Br bond to Br (may bothbe shown at start) (1)
Transition state including minus charge (and product) (1)
Do not penalise if C2H5 shown instead of C3H7.Bonds in transition state can be dotted.Do not penalise the missing H atoms in alkyl groups in
mechanism.
3
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Acceptable Answers Reject Mark
17 (d)QWC
(Primary and tertiary) carbocationintermediates have different stabilities (1)as (inductive effects of) alkyl groups stabilisetertiary carbocation (1)
OR
Steric hindrance differs for attack on primary
and tertiary carbon (in the molecule) / lessspace available for attack by OH— on tertiarycarbon / more space for attack by OH— onprimary carbon (1)as bulky / three alkyl groups obstruct attack(1)
“Tertiarybromoalkanesreact by SN1”withoutfurtherexplanation
carbocationintermediateshave differentreactivity
steric
hindrance incarbocation
2
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Acceptable Answers Reject Mark
18 (a)(i) (Acid) hydrolysis substitution 1
QuestionNumber
Acceptable Answers Reject Mark
18 (a)(ii) K2Cr2O7 / Na2Cr2O7 / Cr2O72—
Potassium dichromate((VI)) / sodiumdichromate((VI)) / dichromate((VI)) ions
ALLOW manganate((VII)) ions, etc
Just“dichromate”
chromates
Correctformula with
wrong nameand vice versa
Incorrectoxidationnumber
1
QuestionNumber
Acceptable Answers Reject Mark
18 (a)(iii) Lithium tetrahydridoaluminate/ lithiumaluminium hydride/ LiAlH4 (in dry ether)
Just [H—] 1
QuestionNumber
Acceptable Answers Reject Mark
18 (a)(iv) Methyl butanoate (1)
CH3CH2CH2COOH + CH3OH ! CH3CH2CH2COOCH3 + H2O (1)
ALLOW ! IGNORE state symbols even if wrong
Methylbutoate
2
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Acceptable Answers Reject Mark
18 (a)(v)CH
3CH
2CH
2C
O
Cl Don’t penalise undisplayed methyl groups ashere.COCl must be displayed as above.
C3H7 forCH3CH2CH2
1
QuestionNumber
Acceptable Answers Reject Mark
18 (b)(i) Nitrogen inert / unreactive / less reactive(than oxygen)
OR
Oxygen might react with chemicals goingthrough column / sample might oxidise
1
QuestionNumber
Acceptable Answers Reject Mark
18 (b)(ii) Solubility (in liquid / stationary phase)
OR
Interaction with liquid / stationary phase
OR
Interaction between mobile and stationaryphase
OR
Attraction for liquid / stationary phase
OR
Strength of (named) intermolecular forces
OR
Adsorption on liquid / stationary phase
OR
Absorption on liquid / stationary phase
Size of molecule /
molar mass
Polarity,unless withexplanation
Boiling point /volatility
Viscosity
Attraction forcarrier gas
Just a namedintermolecularforce
Just ‘retentiontime’
Density
1
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QuestionNumber
Acceptable Answers Reject Mark
18 (c)(i)
O
H
CH3
C CH2
O
C O
H
CH3
C CH2
O
C
OR
CH3
H
CH2
O
C O C
H
CH3
CH2 C
O
OC
Ester link including C=O (1) Rest of polymer with oxygens at end correct (1)
All H atoms must be shown.
PENALISE lack of displayed C=O once only ACCEPT Without brackets around formula but bonds atend should be shownMore than two correct unitsIGNORE n after brackets
2
QuestionNumber
Acceptable Answers Reject Mark
18 (c)(ii) Hydrolysis
OR
Splits / breaks ester link
OR
polymer breaks down to monomers
OR
equation showing hydrolysis
Just ‘breakspolymer down’
1
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QuestionNumber
Acceptable Answers Reject Mark
19 (a)(i) (K p =) pCH3CO2HpCH3OH (x) pCO
Partial pressure symbol can be shown in variousways, eg pp, pCO, (CO)p, etc
ALLOW p in upper or lower case, roundbracketsIGNORE units
[ ]State symbolsgiven as (l)
+ in bottomline
1
QuestionNumber
Acceptable Answers Reject Mark
19 (a)(ii) P CH3OH = 4.9 (atm) (1) P CO = 4.9 (atm) (1)
1 mark for recognition that pressures are equal
IGNORE units
2
QuestionNumber
Acceptable Answers Reject Mark
19 (a)(iii) K p = ((22.2)/(4.9)2)= 0.925 (1)
atm—1 (1) stand alone mark but must matchexpression used in (a)(iii)
OR
9.25 x 104 Pa—1 / 92.5 kPa—1 (2)
ALLOW TE from (a)(i) if inverted and/or (a)(ii)
Answers toother than 3significantfigures
2
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QuestionNumber
Acceptable Answers Reject Mark
19 (b)(i) CH3OH: 3.2CO : 3.2 (1) for both values
CH3CO2H: 46.8 (1)
ALLOW TE for moles of ethanoic acid based onnumbers of methanol and carbon monoxideused, as long as moles of methanol and carbonmonoxide are equal and moles ethanoic acid +moles methanol = 50
2
Question
Number
Acceptable Answers Reject Mark
19 (b)(ii) 46.8 x 32 = 28.2 / 28.1504 (atm)53.2
IGNORE sf except 1
Value = 28.16 if mol fraction rounded
ALLOW TE from (b)(i)
28.1
46.8 x 32 =50
29.95 (atm)
1
QuestionNumber
Acceptable Answers Reject Mark
19 (b)(iii) exothermic as yield / pp of ethanoic acid /conversion of reactants/ Kp is higher at lowertemperature / as equilibrium moves (right) atlower temperature
ALLOW if partial pressure of ethanoic acid < 22.2 atmin (b)(ii), endothermic as yield / pp of ethanoic
acid / conversion of reactants/ Kp is lower atlower temperature
1
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QuestionNumber
Acceptable Answers Reject Mark
19 (c)(i) No effectandother concentrations change to keep Kp constant / Kp is only affected by temperature/as equilibrium moves (right) to keep Kp constant / change in pressure does not changeKp
As Kp is aconstant
1
QuestionNumber
Acceptable Answers Reject Mark
19 (c)(ii) Yield increased to restore fraction / quotient /
partial pressure ratio back to Kp
ALLOW (equilibrium moves) to use up themethanol /answers based on entropy or LeChatelier
Correct prediction in (c)(i) and (c)(ii) withinadequate explanations scores 1 mark in(c)(ii)
Just‘equilibriummoves to theright’
1
QuestionNumber
Acceptable Answers Reject Mark
19 (d) Mark independently
Reaction can occur at lower temperature / haslower activation energy / requires less energy(1)less fuel needed / fewer emissions (from fuels)/ fewer raw materials needed / less naturalresources used (1)
OR
Enables use of an alternative process withhigher atom economy (1) fewer raw materials needed / less naturalresources used (1)
Answer basedon car exhaustemissions
2
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Acceptable Answers Reject Mark
20 (a)(i) Correct answer with or without working scores2 marks
[H+] = (1 .00 x 10—14/ 0.250) = 4 x 10—14 (1)
pH = (13.39794 =) 13.4 (1)
OR
pOH = -log 0.250 = 0.602 (1)
pH = (13.39794 =)13.4 (1)
ALLOW TE in second mark if error in [H+] calculationgives pH more than 73 or more sf IGNORE rounding errors e.g. accept 13.39
2
QuestionNumber
Acceptable Answers Reject Mark
20 (a)(ii) (K a =) [CH3COO—][H+] (1) [CH3COOH]
ALLOW H30
+ instead of H+
[A—][H+] if key to symbols given[HA]
IGNORE state symbols
[H+]2 [CH3COOH]
1
QuestionNumber
Acceptable Answers Reject Mark
20 (a)(iii) Correct answer with or without working scores2 marks
1.7 x 10—5 = [H+]2 (1) 0.125
[H+] = 1.46 x 10—3
pH = 2.84/2.8 (1)
no TE from an incorrect [H+]
2
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QuestionNumber
Acceptable Answers Reject Mark
20 (a)(iv) pH = 4.8 / 4.77 (1)
pH = pK a / [H+] = K a (when acid is half neutralized) (1)
H+ = K a
2
QuestionNumber
Acceptable Answers Reject Mark
20 (a)(v) Sigmoid curve starting between pH 2 and 4(2.8), ending between pH 12 and 14 inclusive(1)
with steep rise (may be vertical or gentlysloping) of between 3 – 7 units between pH 6and 12. Sloping section should not extend overmore than 5cm3. (1)
When 12.5 cm3, NaOH added. (1) ALLOW tolerance for grid
Reverse curves lose first mark
3
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Acceptable Answers Reject Mark
20 (a)(vi) First markThymolphthalein more suitable as it changes(from colourless to blue) in steep region of titration (pH 8.3 to 10.6)/ at the equivalencepoint / at the end pointORthymolphthalein has pH range in steep regionof titration (1)
Second markMethyl yellow changes (from red to yellow atpH 2.9 to 4) before equivalence point / beforethe end point / doesn’t change in steep section
ORMethyl yellow has pH range before / outsidesteep region of titration (1)
ALLOW ‘Thymolphthalein more suitable as itchanges at the equivalence point but methylyellow does not.’ This scores 2 marks
OR
First markpKin ± 1 must lie within vertical region on
titration curve (1)
Second markhence thymolphthalein is suitable and methylyellow is not (1)
2
QuestionNumber
Acceptable Answers Reject Mark
20 (b) Sodium ethanoate/ CH3COONa
Potassium ethanoate / CH3COOK
ALLOW other cations as alternatives to sodium
Use of sodium
hydroxide(because it’sin food)
1
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QuestionNumber
Acceptable Answers Reject Mark
21 (a)(i) "Sosystem = 109.2 + (6x 69.9) – 343 (1)
=(+)185.6(J mol–1 K-1) / (+)186 (J mol–1 K-1)(1)
OR
(+)0.186 (kJ mol–1 K-1) (2)
IGNORE units even if incorrect
correct answer with no working scores 2
Value using 1 for H2O = -163.9 scores 1
Use of value for H2O(g) (188.7) gives898.4 (J mol–1 K-1) (1)
correct value with incorrect sign scores 1
185 2
QuestionNumber
Acceptable Answers Reject Mark
21 (a)(ii) Yes as (solid and) liquid forms (from solid) /number of moles increases
OR
If "Sosystem in (i) is negative the sign is not as
expected as liquid forms from solid / numberof moles increases
Disorderincreases,with no ref toliquid ornumber of moles
1
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Acceptable Answers Reject Mark
21 (a)(iii)First mark
"Sosurroundings = –88.1 x (1000 ) (1)
298
Second mark= -295.6375= -295.6 J mol-1 K-1 (1) correct units must be shown but order notimportant
OR
-0.2956 kJ mol-1 K-1 (1) correct units must be shown but order notimportant
correct answer with or without working andcorrect units scores (2)ignore sf except 1
correct value with positive sign scores 1
2
QuestionNumber
Acceptable Answers Reject Mark
21 (a)(iv) (185.6–295.6)= -110 (J mol-1 K -1 )
OR
-0.110 ( kJ mol-1 K -1)
could use 186 or 296 etc
TE from (a)(i) and (iii)
(+)602.8 (J mol-1 K -1 ) if value for 6H2O(g) wasused in (a) (i)
-459.5 (J mol-1
K -1
)
if value for one H2O wasused in (a) (i)
Answers wherevalues in J areadded to kJ
1
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QuestionNumber
Acceptable Answers Reject Mark
21 (a)(v) Decomposition (at 298 K) will not occur as
"Sototal is negative / Reactions are only
spontaneous if total entropy change is positive/ decomposition not thermodynamicallyfeasible / (hydrated cobalt chloride) isthermodynamically stable
TE if answer to (a)(iv) is positive showingdecomposition (at 298 K) may occur
OR
Positive total entropy change doesn’t indicaterate of reaction
1
QuestionNumber
Acceptable Answers Reject Mark
21 (b)(i) First markThermometer (1)
Second mark (dependent on first)depends on choosing thermometer
as temperature change is small /(%) error in balance smaller than fortemperature reading(%) error in pipette smaller than fortemperature reading(can be shown by calculation) /as scale with greater degree of precisionneeded / scale with more graduations needed(1)IGNORE any references to ‘accuratethermometer’
2
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Acceptable Answers Reject Mark
21 (b)(ii) Use more cobalt chloride / less water (1)
To increase temperature rise (1)
Mark independently
Just ‘use morereactants’
Use morecobaltchloride andmore water
repeat expt
add a lid orextrainsulation to
beaker
use distilledwater
2
QuestionNumber
Acceptable Answers Reject Mark
21 (c)(i)QWC
Radius (of cation) increases (down group)OR any two values of radius:Mg 2+ = 0.072, Ca 2+ = 0.100 / Sr 2+ = 0.113 (nm)data may be shown beside the table (1)
Radius Co2+ = 0.065 nmOR Co2+ radius smaller than other ions (1)
Data on EITHER Co2+ OR data showing increasein radius down Group II required for BOTH of first two marks
Force of attraction between ions decreases (asradius of ions increases) / charge density of ions decreases / negative ion can come closer
to nucleus of positive ion (1) ALLOW “weaker ionic bonds”
Predict lattice energy –2550 to -2900 (kJ mol-1)(1)
IGNORE sign
Atomic radiiunless ionicradii alsogiven
Radius of cobaltchloride
Polarisingpowerdecreases
4
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Acceptable Answers Reject Mark
21 (c)(ii)QWC
First markReference to enthalpy of hydration (may be in
equation "H solution
= -LE + "H hydration
) (1)
Second markSolubility depends on relative size of latticeenergy and enthalpy of hydration (1)
Third markEITHER Solubility more likely if "H solution is negative
OR
(If "H solution is positive,) may / will dissolve if "Stotal is positive
ACCEPT solvation instead of hydration
3
QuestionNumber
Acceptable Answers Reject Mark
21 (d)QWC
First markThird ionization energy high(er) for Mg / Mg =
7733 kJ mol
–1
, (third ionization energy for Co =3232 kJ mol-1) (1)
Second mark(Third ionization energy for Mg is high) becausethe electron is being removed from an innershell / full shell / 2p level / 2p orbital (1)
OR
Not compensated by higher lattice energy for
Mg3+ (and so "H formation of MgCl3 would be highly
endothermic) (1)
2
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OH2
OH2
V
OH2
OH2
H2O
H2O
3+
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–
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Mark Scheme (Results)
June 2010
GCE
GCE Chemistry (6CH08/01)
Edexcel Limited. Registered in England and Wales No. 4496750Registered Office: One90 High Holborn, London WC1V 7BH
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QuestionNumber
Acceptable Answers Reject Mark
1 (f) Pale blue ionsCr2+ / Cr(H2O)n
2+ chromium(II) / Cr(II) (1)
Role of zincReducing agent / Reduces / Reduction /providing electrons (1)
Cu2+2
QuestionNumber
Acceptable Answers Reject Mark
1 (g) Green ionsCr3+/ chromium(III) / Cr(III) (1)
Explanation
The Cr2+
/ chromium(II) / Cr(II) (allow ‘bluespecies’) is oxidized by (oxygen in) the air (1)
Ignore water ligandsAllow oxidized by oxygen
2
6CH08_01 1006 4/14
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QuestionNumber
Acceptable Answers Reject Mark
2 (a)(i) OH / hydroxyl group presentORCompound could be an alcohol / OH or acarboxylic acid / COOH
Hydroxide /OH—
alcohol /carboxylic acidalone
1
QuestionNumber
Acceptable Answers Reject Mark
2 (a)(ii) P is (an alcohol) not a carboxylic acid
Allow P is an alcohol if in (a)(i) P is describedas “an alcohol or a carboxylic acid”Ignore primary and/or secondary
Alcoholwithout threecarbons
1
QuestionNumber
Acceptable Answers RejectMark
2 (a)(iii) P contains the group CH3CH(OH)! / P is a 2-ol
Allow P is propan-2-ol / secondary alcohol
P is amethylketone/ ethanol /methyl alcohol
1
QuestionNumber
Acceptable Answers Reject Mark
2 (a)(iv) P is propan-2-ol / CH3CH(OH)CH3
OH
or
H3C
C
CH3
HO
H
No TE on earlier incorrect answer
Molecularformula only
1
QuestionNumber
Acceptable Answers Reject Mark
2 (a)(v) Peak is caused by (CH3CHOH )+ / C2H5O+ /
CH2CH2OH+ (1) stand alone
(molecular ion (of propan-2-ol) will fragmentby) loss of one CH3 group / CH3
" / CH3 radical(1)Second mark can be awarded only if ion hasrelative mass of 45Allow the molecule fragments (instead of molecular ion)
Allow equations with charge not balanced
Formulawithoutpositivecharge
Breaking C-Cbond on itsown
CH3+
2
6CH08_01 1006 5/14
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QuestionNumber
Acceptable Answers Reject Mark
2 (b)(i) Hydrogen chloride / HCl
Allow hydrochloric acid / HCl(aq)
HCl and POCl3 1
QuestionNumber
Acceptable Answers Reject Mark
2 (b)(ii) Q is a carboxylic acid / COOH /
C
OH
O
Allow CO2H / propanoic acid / carboxylic alone
Carboxylate 1
QuestionNumber
Acceptable Answers Reject Mark
2 (b)(iii) Q is propanoic acid / CH3CH2COOH /CH3CH2CO2H / C2H5COOH
OH
O
H3C
H2C
C
OH
O
1
6CH08_01 1006 6/14
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QuestionNumber
Acceptable Answers Reject Mark
3 (a) Fe + 2H+ ! Fe2+ + H2
Fe + 2H3O+ ! Fe2+ + H2 + H2O
Ignore state symbols and correct sulfateformulae
Non ionicequation
1
QuestionNumber
Acceptable Answers Reject Mark
3 (b) Effervescence / fizzing stopped/no morebubbles of gas given off
Allowno more gas given off
All irondissolved
Steamy fumes(for gas)
1
QuestionNumber
Acceptable Answers Mark
3 (c)(i)
Ignore omission of trailing zeros
Titre /cm3
23.35 23.05 22.70 23.00 22.95 (1)
Titresused(! or
")
" ! " ! ! (1)
2
QuestionNumber
Acceptable Answers Reject Mark
3 (c)(ii) ((23.05 + 23.00 + 22.95) ÷ 3) = 23.00 (cm3)
Allow 23 / 23.0
TE from (c)(i)
1
6CH08_01 1006 7/14
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3 (c)(iii) (A) Moles MnO4– (in titre) = 23.00 x10-3 x .022
= 5.06 x 10-4 (1)
(B) Moles Fe2+ in 250 cm3 = 10 x 5 x Answer in(A) (= 0.0253) (1)
(C) Mass of Fe = Answer in B x 55.8 (= 0.0253 x55.8 =1.41 (g)) (1)
(D) % iron =100 x answer in C ÷ 1.48 (= 95.4 %)(1)
Ignore SF except 1 SFIgnore correct intermediate rounding of
calculated valuesAllow 56 for Ar of iron (95.7 %)Allow TE from (c)(i) and (ii)Correct answers with no working score fullmarks
% > 100 %
4
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3 (d) Iron(II) ions: Pipetteandsulfuric acid: measuring cylinder (1) both needed for the mark
An exact volume of iron(II) ion solution isneeded but only an approximate volume of /excess sulfuric acid (1)The second mark may be awarded if a buretteand measuring cylinder are given
Allow any recognisable spelling of pipette, egpipet
Just pipettemore accuratethanmeasuringcylinder
2
6CH08_01 1006 8/14
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4 (a) Amount of phenylamine = 9/93 / 0.0968 (mol)(1) = amount of ethanoic anhydride
Mass ethanoic anhydride =102 x 9/93 = 9.87 (g)(1)
Ignore SF except 1 SFCorrect answer with no working scores fullmarksMr values reversed scores max 1 only if a molecalculation is clearly shown
2
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4 (b)(i) To ensure that all the phenylamine reacts So ethanoicanhydride is inexcess
To ensurecompletereaction
1
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4 (b)(ii) Reaction is exothermic / produces heat
Allowreaction is vigorousso that the temperature does not increase (toomuch)Ignore references to the reaction being violent,dangerous, explosive etc
1
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4 (b)(iii) Mistake:The condenser water flow is wrong way roundso air may be trapped/jacket will not be full of water (1) Allowcooling not so effective / flammable liquidmight escapeCorrectionReverse the flow of water (1)
Mistake:Flammable liquids are being heated with aBunsen/naked flame (1) Correction
so the Bunsen burner should be replaced by ahot plate (allow water bath) (1) OR Mistake:Heating with a Bunsen too strong (so glass maycrack) (1) CorrectionUse micro-burner/gauze (1)
4
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4 (b)(iv)
Funnel (conical allowed) with grid / line /horizontal filter paper (1)
Side-arm conical flask (with valve orconnection to a pump) (1)
Reduced pressure achieved by:Flow of water through the pump/valve/can beshown in diagram (reduces pressure in theflask) (1)
Allow using a (vacuum / suction) pumpconnected to side-arm (connection may beshown in diagram)(1)
3
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4 (c) Mass of N-phenylethanamide if 100% yield= 135 x 9/93 (1) = 13.06 g
Yield = 100 x 7.49/13.06 = 57.3 % (1)
AlternativelyMoles phenylamine =9/93 = 0.0968Moles N-phenylethanamide = 7.49/135 = 0.0555
(1) Yield = 100 x .0555/.0968 = 57.3 % (1)
Correct answer with no working scores (2)
Ignore sf except 1 sf Yields greater than 100 % score zero
100 x 7.49/9= 83.2 % (0)
2
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4 (d) Some of the N -phenylethanamide will remainon the filter paper/will be deposited on thesides of the glassware/in solution (and will notbe recovered by filtration)
1
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4 (e) The product was not dry / was damp / water(still) present
Ignore reference to impurities present
1
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