A-LEVEL PAPER 2 PP6 MS

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2.

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3.

	
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4.   (a)     Theoretical mass produced = 180 × 2 / 138 = 2.61 g
Using 1.76 × 100 / 2 is a chemical error (CE), scores 0 / 2
1
Percentage yield = 1.76 × 100 / 2.61 = 67.5%
Correct answer scores M1 and M2.
Accept 67.4%
Do not penalise precision but answers must be to at least two significant figures.
1
(b)     Crystals lost when filtering or washing / some aspirin stays in solution / other reactions occurring
Ignore references to impurities.
1
[3]

5.         Advantage; reaction goes to completion, not reversible or faster
                1
	Disadvantage; reaction vigorous/dangerous
(exothermic must be qualified)
          or HCl(g) evolved/toxic
or CH3COCl expensive
NB     Allow converse answers
     Do not allow reactions with other reagents e.g. water
     or ease of separation
1
 [2]

6.	Test                  silver nitrate (solution) (M1)
Allow an alternative soluble silver salt eg fluoride, sulfate.
Do not allow ‘silver ions’ but can access second mark.
Incorrect formula loses this mark but can access second mark.
Do not allow ‘silver’ or an insoluble silver salt and cannot access second mark.
Ignore references to acidification of the silver nitrate.
If an acid is specified it should be nitric acid, but allow sulfuric acid in this case as there are no metal ions present.
If hydrochloric acid is used, CE = 0 / 2.
Do not allow ‘add water’.
1
Observation      white precipitate (M2)
Ignore ‘cloudy’.
Do not allow ‘white fumes’ or ‘effervescence’.
Do not allow this mark if test reagent is incorrect or missing.
Allow named indicator paper or named indicator solution for M1.
Allow correct colour change for M2.
1
[2]

7.   (a)     (i)      AlCl3 or FeCl3
If wrong no further marks.
1

Correct equation scores 2 - contrast with (b)(iii)
Allow + on C or O in equation.
1
(ii)     Electrophilic substitution
Ignore Friedel crafts.
1
	OR	
•  + must be on C of RCO here
•  M1 arrow from within hexagon to C or to + on C
•  Gap in horseshoe must approximately be centred around
   C1 and not extend towards C1 beyond C2 and C6
•  + not too close to C1
•  M3 arrow into hexagon unless Kekule
•  allow M3 arrow independent of M2 structure, i.e. + on H in
   intermediate loses M2 not M3
•  ignore base removing H for M3
3

(iii)    (CH3CO)2O + C6H6  C6H5COCH3 + CH3COOH
OR

Correct equation scores 1 – contrast with (b)(i)
Not allow molecular formula for ethanoic anhydride or ethanoic acid.
1
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8.              (i)      C8H8O2
1
(ii)     any two from

Allow –CO2–      allow C6H5 
2
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9.         	CO2/CO/CH4 may be produced during H2 manufacture/building the plant/transport/operating the plant
1
[1]
 
10.       4
1
[1]
 
11.  (a)     (i)      2
1
(ii)     0
1
(b)    (i)      K = 
 
Correct answer for k with or without working scores 2.
First mark is for insertion of numbers into a correctly rearranged rate equ , k = etc.
1
  = 5.05      (range allowed 5.03−5.07)
AE (−1) for copying numbers wrongly or swapping two numbers.
1
mol−2 dm+6 s−1
Mark units separately, ie only these units but can be in any order.
1
(ii)     8.3 × 10−6 (mol dm−3 s−1)
Allow 0.83 × 10−5.
Ignore units.
OR if not 8.3 × 10−6, look at their k in part(i) and if not 5.05
Allow ecf for their (incorrect) k × (1.64 × 10−6)
1
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12.		(a)     5
1
			(b)     2
1
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13.	(a)    Heating speeds up (hydrolysis / breaking of peptide bonds)
OR forms non-sweet (amino acids)
1
(b)     (2-)aminobutanedioic acid OR
2 not necessary but penalise other numbers at start
(2-)aminobutane(-1,4-)dioic acid
1,4 not necessary but penalise other numbers and 1,4 must be in correct place (QoL)
1
(c)
allow –CO2–
allow NH2–
1
(d)
allow –CO2–
allow +NH3–
don’t penalize position of + on NH3
1
(e)     (i)     M1    Compounds/molecules with same structural formula
Not just structure
1
M2   But with bonds/atoms/groups arranged differently in space or in 3D
Allow –with different spatial arrangement of atom/bond/group
1
Independent marks
(ii)     (Plane) polarised light
1
Rotated in opposite directions
Not bent or turned or twisted; not different directions (QoL) 
1
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14.    H                                   CH3CN or ethanenitrile
1
S                                   CH3CH2NH2 or ethylamine 1Step 1 KCN
1
                                      aq/alcoholic
1
Step 2                           H2
1
                                      Ni
1
W                                   secondary amine
1
                                      
1
                                      nucleophilic substitution
1
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15.	In each section
•        If wrong or no reagent given, no marks for any observations;
•        Penalise incomplete reagent or incorrect formula – but mark observations
•        Mark each observation independently
•        Allow no reaction for no change / no observable reaction in all three parts, but not none or nothing
•        Q says one test. If two tests are given, score zero
(a)
  	 	K2Cr2O7 / H+	KMnO4 / H+	Lucas test (ZnCl2 / HCl)	
1
 
 	R
Primary alcohol	(Orange) goes green Penalise wrong starting colour	(purple) goes colourless / decolourises allow goes brown	No cloudiness	
1
  	S
Tertiary alcohol	no change / no observable reaction	no change / no observable reaction	Rapid cloudiness	
1
Allow acidified potassium manganate and acidified potassium dichromate without oxidation numbers
(b)
  	 	Na2CO3 / NaHCO3 named carbonate	metal eg Mg	named indicator	
PCl5      PCl3
      SOCl2
Named alcohol + HCl / H2SO4
1
 	T
ester	no change / no observable reaction	no change / no observable reaction	no effect	
no change / no observable reaction
1
  	U
Acid	Effervescence or (CO2) gas formed	Effervescence or (H2) gas formed	acid colour	
Fumes / (HCl) gas formed
Sweet smell
1
(c)
  	 	Fehling’s / Benedict’s	Tollens’ / [Ag(NH3)2]+	 	
K2Cr2O7/ H+	

I2 / NaOH
1
 	V
Ketone	no change / no observable reaction	 	
no change / no observable reaction	

no change / no observable reaction	

Yellow ppt
1
 	W
aldehyde	Red ppt	Silver mirror	 	
(Orange) goes green Penalise wrong starting colour	

no change / no observable reaction
1
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16.   (a)      OH acid (present in acid not in ester)
Allow absorption at 2500–3000 cm–1 in acid.
1
(b)     C=O or (absorption at) 1680–1750 cm–1
(present in acid not in alcohol)
Allow correct distinction between 3230–3550 cm–1 for OH alcohol and 2500–3000 cm–1 for OH acid.
1
(c)     Comparison with known spectrum
1
(Exact) match (with known spectrum)
1
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17.  (a)    M1  Lone pair on N labelled b more available / more able to be donated than lone pair
      on N labelled a
Ignore N(b) more readily accepts protons.
Ignore N(b) is stronger base.
1
M2  lp or electrons or electron density on N labelled a:
      delocalized into_(benzene) ring
QoL
1
M3  lp or electrons or electron density on N labelled b:
      methyl / alkyl groups electron releasing or donating or (positive) inductive
      effect or push electrons or electron density
QoL
1
(b)     C19H24N2
Any order.
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11
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18.	Minimum volume and hot water:
Note that this question is worth a total of 5 marks.
Any two from:
to obtain saturated solution
to increase yield / reduce amount left in solution
enable crystallisation (on cooling)
Do not allow ‘because acid doesn’t dissolve well in cold water’.
Max 2
Filtered hot: to remove insoluble impurities / to prevent crystals forming during filtration
1
Cooled in ice: to increase amount of crystals that are formed
Do not allow ‘to cool quickly’.
1
Washed with cold water: to remove soluble impurities
Allow ‘washing with hot water would dissolve some of the crystals’.
1
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19.	(a)		
	(b)		
	(c)		
	(d)		
	(e)	
	
	(f)		
		
	(g)		
	(h)		
	(i)		
	(j)	
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