Question Answer Mark Guidance (a) monomers join/bond/add/react/form polymer/form chain AND another product/small molecule e.g. 2 /l IGNRE two when referring to monomers, ie (two) monomers... (b) (i) QW must spell AND use monomer(s) correctly throughout ALLW correct structural R displayed R skeletal formula R mixture of the above (as long as unambiguous) ALLW benzene ring for 6 5 End bonds MUST be shown (do not have to be dotted) ester link Note: Any ester link shown must be correct rest of the structure 2 ALLW one or more repeat units but has to have a whole number of repeat units (ie does not have to be two) For ester, D NT ALLW ALLW structure with no at left end and at right end (ii) IGNRE brackets IGNRE n ALLW correct structural R displayed R skeletal formula R mixture of the above (as long as unambiguous) ALLW one or more repeat units but has to have a whole number of repeat units (ie does not have to be two) End bonds MUST be shown (do not have to be dotted) IGNRE brackets IGNRE n
Question Answer Mark Guidance (c) compound ALLW correct structural R displayed R skeletal formula R mixture of the above (as long as unambiguous) ALLW 2 ( 3 ) compound D and compound E ALLW D and E by EF from an incorrect structure of provided that contains a double bond and molecular formulae of D and E is 4 8 3 with 2 added across double bond 3 (d) (i) ALLW correct structural R displayed R skeletal formula R mixture of the above (as long as unambiguous) e.g. ( 3 ) 2 D NT ALLW IGNRE working (ie other structures) provided correct structure of propan-2-ol is shown IGNRE name (even if wrong)
Question er Mark Guidance (d) (ii) ALLW correct structural R displayed R skeletal formula R mixture of the above (as long as unambiguous) R (2-)methylpropanoic acid R acid anhydride: D NT ALLW incorrect name (will N a correct structure) (iii) ALLW acyl chloride: ( 3 ) 2 l IGNRE working provided correct structure of propan-2-ol is shown ANNTATINS MUST BE USED ydrogen bonds form with water Note: an be shown in diagram as dashed line, ie ---- (no label required) D NT N hydrogen bond from an incorrect hydrogen bond in diagram Mandelic acid forms more hydrogen bonds (with water) RA Mandelic acid has an extra R 2 groups R has a group RA 3 ALLW a diagram showing hydrogen bonds with water, dipole and lone pair are not required ALLW a hydrogen bond to =, ie =--- IGNRE bond angles Diagram does not need to show all of mandelic acid (IGNRE if wrong) ALLW any comparison of numbers of hydrogen bonds provided that mandelic acid has more hydrogen bonds D NT ALLW No groups in ester (as there are) D NT ALLW reference to / hydroxide IGNRE reference to carbon chain and van der Waals forces Note: If a response compares Ester with Ester 2 rather than with mandelic acid, maximum of 2 marks: st mark hydrogen bonds 2nd mark Ester 2 has more s/oxygens R Ester 2 forms more hydrogen bonds
Question Answer Mark Guidance (d) (iv) To test for (adverse) side effects R to test toxicity ALLW a stated adverse side effect, eg allergy, carcinogenic, etc R to test for irritation IGNRE references to optical isomers, chirality, etc Total 3 IGNRE vague statements such as harmful to skin, dangerous to skin, corrosive to skin, reacts with skin ALLW company liable to litigation/damages
2 Equations 3 + 4[] 3 2 3 + [] 3 Reduction reagents and observation Methylglyoxal is reduced by NaB 4 ANNTATINS MUST BE USED Throughout question, ALLW correct structural R displayed R skeletal formula D NT ALLW molecular formulae ALLW partial reduction (ie reduction of either = group) [] implies reduct [] implies oxidat reduced AND reagent are both required for the mark ALLW link to equation with [] for reduction ALLW LiAl 4 as alternative for NaB 4 ALLW any recognisable attempt at name IGNRE any reference to acids xidation reagents and observation Methylglyoxal is oxidised by 2 S 4 AND K 2 r 2 7 bservation: turns green R blue oxidised AND reagent are both required for the mark ALLW link to equation with [] for oxidation ALLW Na 2 r 2 7 instead of K 2 r 2 7 ALLW + AND r 2 7 2 R + AND r 4 2 If name given, ALLW dichromate R dichromate(vi) ALLW acidified dichromate ALLW any strong acid If formulae used, formulae must be correct R Methylglyoxal is oxidised by Tollens reagent bservation: Silver (mirror) 2 ALLW AgN 3 in ammonia R ammoniacal AgN 3 ALLW oxidised by manganate bservation: decolourised Note: If one reaction is identified as oxidation, assume the other is reduction (and vice versa) Total 5
Question Expected Answers Marks Additional Guidance 3 a i ALLW for both marks 2 2 2 Ester group must be displayed to get both marks and must contain 4 s ALLW for one mark 6 4 2 2 ALLW for one mark 2 2 ALLW Kekulé structure / ( 2 ) 2 ALLW one mark if end bonds missing ALLW mark if the 2 2 is drawn skeletally ALLW for ALLW mark if repeat unit shows a displayed ester group and contains a benzene ring and two other carbons D NT ALLW 6 4 2 2 ii 2 2 2 2 ALLW Kekulé structure/ ( 2 ) 2 2 for ester groups 6 4 if already penalised in a(i)
Question Expected Answers Marks Additional Guidance b i 7 5 2 ALLW any order of elements ALLW 4 0 4 7 5 2 or 4 0 4 = 7 5 2 ii 2 2 2 ALLW / 2 ALLW Penalise incorrect bond linkage in 2b(ii) only. Do not penalise elsewhere on the paper ALLW ( 2 ) 2 c i - (Na + ) 2 ALLW any of the following for mark + Na - or D NT ALLW any other response - Na + or 2 - Na + ii (PGA is) (bio)degradable R photodegradable R hydrolysed (but hydrocarbon based polymers are nonbiodegradable) ne of (bio)degradable R photodegradable R hydrolysed must be spelt correctly if one spelt correctly and another incorrectly spelt ALLW mark ALLW broken down by bacteria (must be spelt correctly) ALLW degrade as alternative to degradable ALLW undergoes hydrolysis as alternative to hydrolysed IGNRE any additional information if the additional information is correct e.g. biodegradable and doesn t produce toxic gases D NT ALLW any additional information if the additional information is incorrect e.g. biodegradable and can be recycled Total 9
Question Expected Answers Marks Additional Guidance 4 a Alternative approaches Tollens test AND silver precipitate/mirror is the aldehyde react with 2,4-DNP() and orange precipitate must be the ketone 2,4-DNP() AND orange precipitate is either aldehyde R ketone ALLW carbonyl R = Tollens test & silver ppt/mirror is the aldehyde Tollens test AND silver precipitate/mirror is the aldehyde react with carbonate/ hydrogencarbonate/ Na/Mg and fizzes/ bubbles/ effervesces/ gas evolved must be the (carboxylic) acid 2,4-DNP() and no orange precipitate is the (carboxylic) acid Tollens test & silver ppt/mirror is the aldehyde 4 ALLW ammoniacal AgN 3 / Ag + (N 3 ) 2 / Ag + (N 3 ) ALLW acidified dichromate R Fehlings as an alternative to Tollens observation turn green R red precipitate respectively ALLW acidified manganagate(vii) and observation as either brown precipitate/decolourised/pale pink ALLW Brady s (reagent) ALLW orange/red/yellow for colour of the 2,4-DNP() precipitate ALLW solid/crystals in place of precipitate IGNRE any reference to melting points ALLW Pl 5 as a test for the acid observation would be white fumes (of l) ALLW detection of (carboxylic) acid by reacting with an alcohol to make an ester but no mark for the observation. D NT ALLW detection of (carboxylic) acid by p or indicator Please annotate, use ticks to show where marks are awarded b Peak in range 2500 3300 (cm ) or (around) 3000 shows [need wavenumber (or range) and bond] D NT ALLW single peak quoted within range 2500 3300 other than 3000 (cm ) for D NT ALLWrange 3200 3550 (cm ) IGNRE any reference to - or =
Question Expected Answers Marks Additional Guidance c Alternative approaches depending on whether or not the aldehyde is correct ALLW 3-methylbutanal, any correct unambiguous structure ALLW two marks for correct aldehyde with no explanation Doublet indicates adjacent is bonded to only R (relative) peak area indicates 2 x 3 (in the same environment) Doublet indicates adjacent is bonded to only AND (relative) peak area indicates 2 x 3 (in the same environment) ALLW doublet/peak at 0.9ppm due to R ALLW the splitting shows adjacent to /environment that contains /proton ALLW 6 s/ protons in same environment D NT ALLW 6 s in same environment next to d i If aldehyde is correct ( 3 ) 2 2 If aldehyde is correct only need to explain doublet R peak areas If aldehyde identified is incorrect if aldehyde is incorrect must explain both doublet or peak areas e.g. 3 3 ALLW displayed/skeletal formulae would score two marks if the doublet and the peak areas were correctly explained 3 2 2 3 ii ketone 3 There are 4 (different ) environments ALLW 2 s are in same environment/equivalent (therefore) it is ketone 2 / 3 3 3 ALLW 3-methylbutan(-2-)one/ any correct unambiguous structure ALLW 2-methylbutan-3-one 3 ( responsible for peak at = 20 ppm) is =/carbonyl carbon Total 2 ALLW
Question Expected Answers Marks Additional Guidance 5 a i The time (from the injection of the sample) for the component to leave the column ALLW time from injection to detection ALLW time spent in column ALLW time taken to reach detector ii They have similar retention times ALLW both are esters therefore partition/adsorption/retention times will be very similar ALLW EF if they describe R f values in part a(i) ALLW same retention times b iii Butylbutanoate ALLW butyl butanoate ALLW but--yl butanoate i hydrocarbon chain must be correct for one mark ester group and ethyl group must be correct for one mark 2 D NT ALLW butanyl butanoate ALLW any correct unambiguous structure/ 3 ( 2 ) 4 2 3 / 3 ( 2 ) 4 2 5 3 ( 2 ) 4 () 4 2 3 D NT ALLW 5 2 3 etc ALLW 2 for ester l ALLW mark for correct 2,4-decadiene structure e. ALLW mark for correct ethyl oate structure e. or 2 2 5 or 2 5
Question Expected Answers Marks Additional Guidance ii 2 R R 2 R ALLW 2 2 any orientation of the three fatty acids c. react phenylethanal with 2 S 4 /K 2 r 2 7 if either phenylethanoic acid or 2- phenyethanol not prepared automatically lose two marks 2. to get phenylethanoic acid/ 6 5 2 mark 2 can be scored if dichromate is used without being acidified 3. react phenylethanal with NaB 4 4. to get 2-phenylethanol/ 6 5 2 2 mark 3 must be correct to score mark 4 5. react phenylethanoic acid with 2-phenylethanol. If both already correctly named ALLW acid and alcohol 6. 2 S 4 if linked to the reaction of an alcohol and acid 7. reflux in either () or (5) or catalyst used in (5) QW must spell catalyst or reflux correctly 7 ALLW + & r 2 2 7 or 2 S 4 /Na 2 r 2 7 - any other oxidising agent or other named acid please consult with TL ALLW LiAl 4 as alternative to NaB 4 phenylethanoic acid & phenylethanol must be unambiguously identified by either name or formula D NT ALLW or oxidised to form(a carboxylic) acid or reduced to form alcohol for marks 2 and 4 ALLW conc 2 S 4 D NT ALLW dilute or 2 S 4 (aq) D NT ALLW just acid catalyst D NT ALLW l, N 3 Please annotate, use ticks to show where marks are awarded Total 3
Question er Mark Guidance 6 (a) (i) ne mark is for positive carbonyl test (Add) 2,4-dinitrophenylhydrazine AND orange/yellow/red precipitate ALLW errors in spelling ALLW 2,4(-)DNP R 2,4(-)DNP ALLW Brady s reagent or Brady s Test ALLW solid R crystals R ppt as alternatives for precipitate ne mark is for negative aldehyde test EITER (Add) Tollens reagent/tollens test AND no change R no reaction R no silver (mirror) ALLW AgN 3 /N 3 (Formulae must be correct) R ammoniacal silver nitrate ALLW Fehling s solution R Benedict s solution AND no (brick-red) precipitate ALLW any response that implies that nothing happens ie no change R no reaction R no silver (mirror) ALLW the aldehyde/pentanal gives a silver mirror (ii) R (Add) 2 S 4 AND K 2 r 2 7 AND no change R no reaction R no green colour st mark Take melting point of orange crystals/derivative/product from 2,4-DNP 2 ALLW + AND r 2 7 2 (Formulae must be correct) ALLW any response that implies that nothing happens IGNRE responses using NaB 4 (as no observations) NTE: a(ii) is marked completely independently of a(i) 2nd mark ompare melting point with known values R compare melting point with value in database/reference book 2 Mark independently of response for st mark D NT ALLW st or 2nd marks for taking and comparing boiling points R chromatograms
Question er Mark Guidance (b) ( Synthesis 6 NTE: ALL Structures MUST have s shown IGNRE bond angles D NT ALLW more than one repeat unit IGNRE brackets and n Ester linkage must be fully displayed ALLW terminal on right (R = on left), i.e. ALLW end bonds shown as ----- D NT ALLW if structure has no end bonds Synthesis 2 2
Question er Mark Guidance Synthesis 3 Mark each structure independently must be connected correctly on BT structures D NT ALLW more repeat units IGNRE brackets and n ALLW terminal on right (R = on left), i. ALLW end bonds shown as ----- D NT ALLW if structure has no end bonds D NT ALLW EF from wrong structure in previous boxes (b) (i Synthesis : condensation AND Synthesis 2: addition AND Synthesis 3: condensation Total All three correct responses required for the mark