5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

1/17

Oxford Cambridge and RSA Examinations

GCE

Chemistr B SaltersAdvanced GCE

Unit F334: Chemistry of Materials

Mark Scheme for January 2013

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

2/17

OCR (Oxford Cambridge and RSA) is a leading UK awarding body, providing a wide range ofqualifications to meet the needs of candidates of all ages and abilities. OCR qualificationsinclude AS/A Levels, Diplomas, GCSEs, Cambridge Nationals, Cambridge Technicals,Functional Skills, Key Skills, Entry Level qualifications, NVQs and vocational qualifications inareas such as IT, business, languages, teaching/training, administration and secretarial skills.

It is also responsible for developing new specifications to meet national requirements and theneeds of students and teachers. OCR is a not-for-profit organisation; any surplus made isinvested back into the establishment to help towards the development of qualifications andsupport, which keep pace with the changing needs of todays society.

This mark scheme is published as an aid to teachers and students, to indicate the requirementsof the examination. It shows the basis on which marks were awarded by examiners. It does notindicate the details of the discussions which took place at an examiners meeting before markingcommenced.

All examiners are instructed that alternative correct answers and unexpected approaches in

candidates scripts must be given marks that fairly reflect the relevant knowledge and skillsdemonstrated.

Mark schemes should be read in conjunction with the published question papers and the reporton the examination.

OCR will not enter into any discussion or correspondence in connection with this mark scheme.

OCR 2013

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

3/17

F334 Mark Scheme

1

Annotat ions used in the detailed Mark Scheme (to include abbreviations and subject-specific conventions).

Annotat ion Meaning

/ alternative and acceptable answers for the same marking point

separates marking points

not answers which are not worthy of credit and which will CON a correct answer

ignore statements which are irrelevant and will NOT CON a correct answer

allow answers that can be accepted

( ) words which are not essential to gain credit

__ underlined words must be present in answer to score a mark

ecf error carried forward

AW alternative wording (replaces the old or words to that effect)

ora or reverse argument

Annotat ions used in scoris:

Annotat ion Meaning

correct response

incorrect response

benefit of the doubt

benefit of the doubt notgiven

error carried forward

information omitted

Ignore

Reject

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

4/17

F334 Mark Scheme

2

Question Answer Marks

1 (a) (i)

C

C N

O

H2CO CH2

H2C CH2

H2C CH2

N

H

H

all correct 2 marks amide link only

2 ALLOW

any correc

mixtures o

CONH

Cs and Hs

IGNOREbrackets

(ii) CONH circled 1 ALLOWadjacent

(iii) 1,6-diamino hexane ORhexane -1,6-diamine

2 If butaneALLOWIGNORE commasALLOW 1,6-hexa

(b) (i)

HO

C

CH2

CH2

CH2

CH2

CH2

NH2

O

1 ALLOWany form

ALLOWcyclic am

N

O

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

5/17

F334 Mark Scheme

3

Question Answer Marks

(ii) condensationANDwater is eliminated/formed/lost

IFcyclic amide in 1b(i) THENaddition AND hydrolysis (of ring) /water added

1 addition or additALLOWsmall moany other named s

(c) (i) (polymer) chains/molecules are (highly) ordered/alignedAW 1 ALLOW labelleddchains by using pa

AWmeans other egstacked closely aarranged regularl

(ii)

PPA chainsareclosertogether ORA

so intermolecular bondsin PPA will be strongerORmore hydrogen bonds in PPAORmore intermolecular bonds in PPA ORA

more energy/heatwill be required tobreak the intermolecular bondsORmelt the polymer OR allowchains to move over each other ORA

3 AS ALWAYSintewith intermolecula

NOTmore areas otogether NOTjustNOTEALL 3 mark

ALLOWany nam

NOT higher temp

(iii) cold-drawing 1 NOTco-polymerisIGNOREnecking

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

6/17

F334 Mark Scheme

4

Question Answer Marks

(d) (i) 1. elimination 2. addition 3. addition

3IGNOREnucleop

(ii) can be used in step 3AW 1 NOT step 2

ALLOW can be sol

can be use

can be rec

(e) acidified dichromate 1 IGNORE

metal catio

name of ac

wrong form

oxidation s

ALLOWH2SO4/HDO NOT ALLOW

Total 17

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

7/17

F334 Mark Scheme

5

Question Answer Marks

2 (a)COOH / carboxyl / carboxylic acid group is a proton/H+donor / loses H+

2 correct equation sALLOWgives H+

Mark separately

(b) (i) CH2OHCOOH + NaOH CH2OHCOONa + H2O 1 ALLOW

CH2OHCOONa+

Na+ CH2OHCOO

IGNOREstate symNOTCH2OHNaC

(ii) 1. moles of NaOHused in titration= 16.00/1000 x 0.250= 0.00400

6 There are severalafter point 2, the the concentration

If final answer isticks where the m

2.ALLOWby imp

The marks are awboldORthe correworking (but no mis wrong)

4. Award if 76 use

2. moles of glycolic acid used in titration= answer from 1, scaled by ratio in equation in 2bi

0.00400

CHECK equation in 2(b)(i)

3A. moles of glycolic acid in 250 cm3= (answer from 2)x 10= 0.0400 mol

OR3B. mass of glycolic in 25 cm3

= (answer from 2)x Mrof glycolic acid 0.304 gOR3C. concentration of glycolic acid

= (answer from 2) x 1000/25 0.16 mol dm-3

4. Mrof glycolic acid = 76.(0)

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

8/17

F334 Mark Scheme

6

Question Answer Marks

5A. moles of glycolic acid in 100 cm3

= (answer from 3A) x 100/14 0.286 molOR5Bi. mass of glycolic acid in 250 cm3

= (answer from 3A) x Mrof glycolic acid 3.04 g

OR5Bii.mass of glycolic in 250 cm3

= (answer from 3B) x 10 = 3.04 gOR5C. concentration of undiluted glycolic acid

= (answer from 3C) x 250/142.86 mol dm-3

ALLOWecf for instepALLOW AcnegonALLOWanswers

The following on tcorresponding coof working or lack21.7 scores 61.22 scores 5 (er12.2 scores 5 (er2.17 scores 5 (er3.04 scores 5 (erthese to other sf Omark less

If one of the answnumber of ticks

6. mass of glycolic acid in 100 cm3undiluted= (answer from 5A) x Mrof glycolic acid

OR = (answer from5B)x 100/14

OR = (answer from 5C/10) x Mrof glycolic acid

= 21.7 (3 sf)ANDcorrect comment

(c) (i)

H3C

O

O CH2CH2CH2CH3

butyl ethanoate

ester link correct

2 IGNORE where this includedALLOWadjacent

ALLOWbutyletha

(ii) butan-1-ol

concentrated sulfuric acid/hydrochloric acid

2 MUST HAVEnumDO NOT ALLOWALLOWformula fIGNOREspelling clear

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

9/17

F334 Mark Scheme

7

Question Answer Marks

(iii) ethanoic acid:hydrogen bonding IGNOREpd-pd

compound D:pd-pd hydrogen bonding is CON

instantaneous dipole induced dipole / id-id in both

3 ALLOWpd-pALLOW Van

(d) (i) The answer requires a comment for a carboxylic acid AND analcohol so award ONE mark from each section below:

CARBOXYLIC ACID(strong) peak at 1743 (cm1) shows C=O in ester not acidORno peak 1700 1725 (cm1) shows no C=O in acidORno broad peak at 2500 3200 (cm1) shows no OH in acid

ALCOHOLno peak greater than 3000 / in range 3200 3600 (allow 3640) sono OH in alcohol

2 answers may

to score eachwhich it is fou

ALLOW carboethanoic acid

FOR OHALFOR C=OAL

(ii) peak at m/z73:CH3COOCH2/ C3H5O2positive charge on any formula

species lost:CH2CH2CH3/ C3H7 (NO charge)

3 ALLOW any cfor both answALLOWC4H9

IFC4H9O+giv

THEN specie

(e) (i) nucleophilicaddition 2

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

10/17

F334 Mark Scheme

8

Question Answer Marks

(ii)

H C H

O

-C N

H C H

OH

CN

H C H

O-

CN

H+or H2O or HCN

HCHO with bond polarity correct CNwith lone pair of electrons on C

both curly arrows correct (lower one must be from C of CN) intermediate ion correct gain of H+from water, HCNor directto form the cyanohydrin

5

ALLOW CNALLOWve c

IGNOREany intermediate

Total 28

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

11/17

F334 Mark Scheme

9

Question Answer Marks

3 (a) (i)repeating unit in DNA is a nucleotide

formed from pentose/sugar/deoxyribose, phosphateand a baseAW

2 mark separate

ALLOW

names fof base

a namedIGNOREribosfor two marksmakes up the

(ii) proteins are formed from amino acid(s) 1

(iii) proteins have moreamino acids than the bases/nucleotides inDNA

from which to construct many unique/different/morestructures/arrangements/combinations to carry genetic data AW

2 ALLOWactuaacids in proteDNA

(b)

N N

CH3

O

O

HDNA chain

DNA chaincorrect formula completed for adenineANDboth H bonds betweencorrect atoms correct polarities for one hydrogen bond lone pair for one hydrogen bond

3

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

12/17

F334 Mark Scheme

10

Question Answer Marks

(c) (i)

HN CH C

CH2

HN

O

OH

CCH2C

O

CHN

O

CH

OH

H3C

CH3

ANY TWO of the THREE CORRECT chiral Cs ONLY

1

(ii) arrows as in (d) (i) 1 IGNOREextraends of chainAny other arro

(iii)

H2N C C

H2C

H O

O-

OH

correct amino acid (see opposite)

correct formula of ion

2 IGNOREany ALLOWany cIGNORE spec

and left

IGNORE

added

negati

COO

NO ecfIFanion formeamino acid

(iv) secondary:

folding/twisting of polypeptide/amino acid chains/primary structure

tertiary:further/final folding OR3D shape/structure

2

ALLOW(alphpleated sheet

ALLOWovera

Total 14

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

13/17

F334 Mark Scheme

11

Question Answer Marks

4 (a) (i)

O O SS

O

O

O

O

O

O

2-

x

xx

x x

xx

xx

xx

xx

xx

xx

x

xx

xx

xx

xx

correct inside oval (around peroxy Os) rest correct

2

ALLOWanot

second mark

(ii) (NH4)2S2O8 1 ALLOW

with co

S2O8(N

(b) S2O82(is the stronger oxidising agent) because

S2O82 hasa more positiveEovalue indicates a greatertendency AW to gain/attract/accept electrons/to

be reduced

ORA ie:S2O8

2 (is the stronger oxidising agent) because Cr2O72 hasa less

positive/ more negativeEovalue

indicates a smaller tendency AW to gain/attract/accept electrons/tobe reducedORindicates a greatertendency AW to lose electrons/to beoxidised

2 without refere

only scores 1

NOT higher fboth statemen

(c) (i) S2O82+ 2I 2SO4

2+ I2correct equation balanced

1 IGNOREstate

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

14/17

F334 Mark Scheme

12

Question Answer Marks

(ii)

1. use filter of complementarycolour to iodine/solution

2. zero colorimeter with water

3. measure absorbance readings of standard solutions/solutionsof known concentration (of iodine)

4. plot calibration graph

5. take absorbance readings of the reacting mixture atknown/certain times AW (must refer to time may state unitsof time)

6. convert absorbance readings to iodine concentrations usingthe calibration curve

QWC:In order to gain the mark for point 3, 5 or 6, absorbance must beusedANDspelled correctly at least once

6 Using starchCANNOT gaiALLOW

filter/wabsorp

green/

suitab

orange/yellowNOT solvent

IGNORErefe

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

15/17

F334 Mark Scheme

13

Question Answer Marks

(iii)

t1/2t1/2

suitable graph sketched

construction lines to determine half-lives from graph

constant half-life (means first order)

3 graph should decreasingfrcurve will do)

at least twosshown on gra

dependent on(numbers on s

(d) (i) homogeneous, reactants and catalyst/Fe3+are in the same phase /state

1 MUSTmentioIGNORE'redoNOT'substratALLOW all in

(ii) Fe2+ 1s22s22p6 3s23p63d6Fe3+ 1s22s22p63s23p63d5

correct number of EXTRAelectrons added14(Fe2+) and 13(Fe3+) both fully correct

2 IGNORE 4s0

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

16/17

F334 Mark Scheme

14

Question Answer Marks

(iii) 1. Fe3+reacts with/oxidises IORA

2Fe3+ + 2I 2Fe2+ + I2

explanation:

the EoofFe3+/Fe2+half-cell is more posit ive / less negativethan that of the I/ I2

half-cell ORAAW

2. Fe2+reacts with/reduces S2O82ORA

S2O82

+ 2Fe2+ 2SO4

2 + 2Fe

3+

explanation:the EoofS2O8

2/SO42half-cell is more positivethan that of

the Fe3+/Fe2+half-cell ORAAW

QWC: to gain the explanation mark for either 1or 2, the datahas to be linked correctly to the reaction

6 IGNORE refevariable valen

ALLOWEoof

ALLOWEoof

NOTEIf answer starmark but ecf sget 5 marks

(e) (i) Rate = k x [S2O82

] x [I

] 2 IGNOREstate

(ii) uses one of the 3 sets of results:1. k = 2.0 x 105/ (0.075 x 0.040)2. k = 4.0 x 105/ (0.150 x 0.040)3. k = 1.0 x 105/ (0.075 x 0.020)

k = 0.0067

mol1dm3s1

3 ecf from part eALLOWstandCorrect numefor calculation

NO ecf from f

ALLOWany nNOT 0.006 N

ALLOWunits

(iii) 2.0 x 105mol dm3s1

2 Mark separate

Total 31

5/28/2018 142261 Mark Scheme Unit f334 Chemistry of Materials January

17/17

Oxford Cambridge and RSA Examinationsis a Company Limi ted by GuaranteeRegistered in EnglandRegistered Office; 1 Hills Road, Cambridge, CB1 2EURegistered Company Number: 3484466

OCR is an exempt Charity

OCR (Oxford Cambridge and RSA Examinations)Head off iceTelephone: 01223 552552Facsimile: 01223 552553

OCR 2013

OCR (Oxford Cambridge and RSA Examinations)

1 Hills Road

Cambridge

CB1 2EU

OCR Customer Contact Centre

Education and Learning

Telephone: 01223 553998

Facsimile: 01223 552627

Email: general.qualifications@ocr.org.uk

www.ocr.org.uk

For staff training purposes and as part of our quality assurance

programme your call may be recorded or monitored