GCE. Chemistry. Mark Scheme for June Advanced GCE 2814/01 Chains, Rings and Spectroscopy. Oxford Cambridge and RSA Examinations

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1 GE hemistry Advanced GE 2814/01 hains, Rings and Spectroscopy Mark Scheme for June 2010 xford ambridge and RSA Examinations

2 R (xford ambridge and RSA) is a leading UK awarding body, providing a wide range of qualifications to meet the needs of pupils of all ages and abilities. R qualifications include AS/A Levels, Diplomas, GSEs, R Nationals, Functional Skills, Key Skills, Entry Level qualifications, NVQs and vocational qualifications in areas such as IT, business, languages, teaching/training, administration and secretarial skills. It is also responsible for developing new specifications to meet national requirements and the needs of students and teachers. R is a not-for-profit organisation; any surplus made is invested back into the establishment to help towards the development of qualifications and support which keep pace with the changing needs of today s society. This mark scheme is published as an aid to teachers and students, to indicate the requirements of the examination. It shows the basis on which marks were awarded by Examiners. It does not indicate the details of the discussions which took place at an Examiners meeting before marking commenced. 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 skills demonstrated. Mark schemes should be read in conjunction with the published question papers and the Report on the Examination. R will not enter into any discussion or correspondence in connection with this mark scheme. R 2010 Any enquiries about publications should be addressed to: R Publications P Box 5050 Annesley NTTINGAM NG15 0DL Telephone: Facsimile: publications@ocr.org.uk

3 1 (a) (i) N S 4 (both acids) conc N (iii) 2 S 4 + N 3 N S 4 / S 4 + N 3 N S 4 1 (iv) N 2 N 2 + N 2 curly arrow from bond to electrophile intermediate curly arrow from bond to bond correct products 4 (v) moles benzene = 3.9 / 78 = actual moles of nitrobenzene formed = 4.9 / 123 = / or theoretical mass nitrobenzene = x 123 = 6.15 (g) % yield = actual / theoretical mass/moles = = 79.67% = 80% 80% without working only scores 1 mark 3 (b) (i) AlBr 3 / Fe / FeBr 3 ALLW All 3 1 bromine decolourised white/cream solid/ppt. 2,4,6-tribromophenol identified by name/structure lone pair from (of ) is delocalised into the ring (or orbital diagram to show) increases the () electron density(around the ring) Br Br more polarised / more attracted ora for benzene 6 QW for correct use of one of the terms electrophile / electrophilic / activation 1 [Total: 20 ] 1

4 2 (a) step 1 N 2 + l / NaN 2 + l below 10 step 2 add to phenol in alkaline conditions / Na (below 10 ) N N N N / / Na ALLW 6 5 not displayed ALLW any substitution position in the dye 5 (b) (i) N=N circled 1 12 carbons 9 hydrogens 2 (iii) S Na D NT ALLW connection errors here 2 N ALLW S 3 2 (c) S (Na N N ALLW just one 1 [Total: 11 ] 2

5 3 (a) (i) mechanism arrow from of N to dipole and curly arrow breaking -bond on = structure of the intermediate curly arrow to of N / 2 / + e.g. 3 3 N N 3 N N N reagents: N + KN / 2 S 4 + KN ALLW Na / N 5 type of reaction: hydrolysis equation: e.g. 3 ()N () + N 3 / 3 ()N () + N 4 2 / N 3 rest of the equation and balancing 3 (b) lactic acid has a chiral centre / optical isomers laboratory sample has both optical isomers / stereoisomers fermentation would contain only one optical isomer AW D NT ALLW just isomers 2 (c) (i) 3 3 ester link rest of structure also correct 2 renewable = made from plants that can be grown AW biodegradable = broken down by bacteria etc AW reason linked to biodegradability e.g. less landfill / less harm to animals / broken down by hydrolysis / no need to burn so no harmful gases etc AW ora reason linked to renewability e.g. does not increase atmospheric 2 AW ora ANY two for 2 (d) 2 3 () as product / 2x lactic acid as reactants rest of the equation correct and balanced ALLW any combination of molecular or structural formulae 2 [Total: 16 ] 3

6 4 (a) (i) N 2 / ringed on structure IGNRE propylamine but con if named as an amide 1 N 2 two N 2 and skeletal rest of the molecule correct 2 N ALLW ecf from non-skeletal 2 (b) (i) + 3 N( N 3 + ) one N 2 protonated both N 2 protonated IGNRE l ALLW N 3 l 2 2 N( N 2 ) IGNRE Na + ALLW Na ALLW ecf from (i) on minor structural errors 1 (c) Pl 5 Pl 3 + l / Sl 2 S 2 + l ( allow Pl 3 3 P 3 for the first two marks ) 3 (d) one peptide linkage correct ALLW N not displayed N 2 ( 2 ) 3 3 N 2 max one mark if N linkage 2 N 3 N one correct dipeptide 2 N ( 2 ) 3 N ALLW ornithine linked by either N 2 group ALLW 3 6 N 2 for the side chain second dipeptide with R groups swapped ALLW ecf for last mark for idea of swapping side chains as long as a peptide is attempted 3 [Total: 12 ] 4

7 5 (a) hex-3-en... al ALLW ene ALLW -1-al 2 (b) 3 2 Br Br 2 NaB 4 / LiAl 4 + ether Br 2 A + 2- / r 2 7 polymerisation addition polymer attempted with two repeats correct side chains 5 (c) ALLW one mark for two correct structures with incorrect labels cis trans ALLW ecf on minor side chain errors 2 [Total: 9 ] 5

8 2814/01 Mark Scheme June (a) To confirm aldehyde or ketone 2,4-dinitrophenylhydrazine / Brady s reagent red / orange / yellow... solid / ppt / crystals To distinguish between aldehyde or ketone warm with ammoniacal silver nitrate / Tollens reagent 2 / acidified r 2 7 silver (mirror) green D NT ALLW recrystallise etc for the 2nd mark ALLW any other suitable tests e.g. Fehlings, Mn 4 5 (b) (i) M written next to the peak at m/e = / 6 5 = 7 = 6 and ALLW ecf on 5 if the peak at 105 labelled 2 (c) (d) D E F No of peaks and areas 3 peaks ratio 3:1:6 4 peaks ratio: 3:2:2:3 2 peaks ratio: 2:3 /4:6 chemical shifts (ppm) splitting AW to describe ( 2) singlet doublet / 1:1 (multiplet) ( 2) singlet 2 x triplet / 1:2: triplet / 1:2:1 (multiplet) quartet 1:3:3:1 9 on D and E, IGNRE any splitting given for the multiplet QW For at least two relevant sentences in which the meaning is clear with correct spelling, punctuation and grammar (ALLW bullet points and note form where appropriate). 1 [Total: 22 ] 6

9 R (xford ambridge and RSA Examinations) 1 ills Road ambridge B1 2EU R ustomer ontact entre Qualifications (General) Telephone: Facsimile: general.qualifications@ocr.org.uk For staff training purposes and as part of our quality assurance programme your call may be recorded or monitored xford ambridge and RSA Examinations is a ompany Limited by Guarantee Registered in England Registered ffice; 1 ills Road, ambridge, B1 2EU Registered ompany Number: R is an exempt harity R (xford ambridge and RSA Examinations) ead office Telephone: Facsimile: R 2010

PMT GCE. Chemistry A. Advanced GCE F324. Mark Scheme for June Oxford Cambridge and RSA Examinations

PMT GCE. Chemistry A. Advanced GCE F324. Mark Scheme for June Oxford Cambridge and RSA Examinations GE hemistry A Advanced GE F324 Mark Scheme for June 200 xford ambridge and RSA Examinations R (xford ambridge and RSA) is a leading UK awarding body, providing a wide range of qualifications to meet the