AS-LEVEL PAPER 2 PP9 MS

1.      (a)     (i)      Hexan-1-ol1
ONLY
1
(ii)     Homologous (series)
ONLY
1
(iii)     Displayed formula for butan-2-ol

All bonds must be drawn out including the O–H bond
Ignore bond angles
1
(iv)    CH3CH2CH2CH2OH + [O]  CH3CH2CH2CHO + H2O
Require this whole equation as written or formulae drawn out
Penalise “sticks”
1
(v)     Displayed formula for butanone
(credit possible enols, ethers and cyclic structures for C4H8O)

All bonds must be drawn out
Ignore bond angles
1
(b)     M1    q = m c ΔT OR calculation 175 × 4.18 × 8
M2    = 5852 (J) OR 5.85 (kJ) OR 5.9 (kJ) (This also scores M1)
M3    0.005 mol, therefore ΔH = –1170 (kJ mol–1)
                          OR ΔH = –1170.4 (kJ mol–1)
                         OR ΔH = –1200 (kJ mol–1)
Award full marks for correct answer
In M1, do not penalise incorrect cases in the formula
Ignore incorrect units in M2
Penalise M3 ONLY if correct answer but sign is incorrect OR value is in J mol–1
If m = 5 × 10–3 OR if ΔT = 281, CE and only allow one mark for correct mathematical formula for M1
If c = 4.81 (leads to 6734) penalise M2 ONLY and mark on for M3 = –1350 (–1347)
3

(c)     (i)      M1    The enthalpy change (or heat change at constant pressure)
when 1 mol of a compound/substance/alcohol
M2    is burned completely in oxygen
OR burned in excess oxygen
M3    with all reactants and products/all substances in
standard states
OR
all reactants and products/all substances in normal states
under standard conditions OR 100 kPa/1 bar and a
specified T/298 K
For M3
Ignore reference to 1 atmosphere
3
(ii)     M1    (could be scored by a correct mathematical
expression)
M1    ΔH = ΣΔHf (products) – .ΣΔHf (reactants)
OR a correct cycle of balanced equations
M2    = 4(–394) + 5(–286) – (–327)
          (This also scores M1)
M3    = – 2679 (kJ mol–1) OR –2680 (kJ mol–1)
Award 1 mark ONLY for (+) 2679 OR (+) 2680
Correct answer to calculation gains full credit
Credit 1 mark if + 2679 (kJ mol–1)
For other incorrect or incomplete answers, proceed as follows
•    check for an arithmetic error (AE), which is either a
     transposition error or an incorrect multiplication; this
     would score 2 marks (M1 and M2)
•    If no AE, check for correct method; this requires either
     a correct cycle with 4CO2 and 5H2O OR a clear
     statement of M1 which could be in words and scores
     only M1
3

(d)     (i)      M1    This is about the change in formula up the series
          Each alcohol in the series (compared with the previous one)
          increases by/has an extra CH2
OR
          has one more C-C and two more C-H

M2    This is about the reaction and bond breaking/making
          Combustion of each alcohol in the series breaks one
          more C-C and two more C-H compared with the previous one
AND forms one more mol CO2 and one more mol H2O
OR
          A statement in which there is the idea that the extra OR
additional OR difference in number of bonds broken
and formed (as the series increases) is the same OR has
the same difference in energy
N.B. If the first statement here for M2 is given, both marks score
2
(ii)     For the two marks M1 and M2
heat loss or heat absorbed by the apparatus
OR
incomplete combustion/not completely burned
OR
The idea that the water may end up in the gaseous state
(rather than liquid) OR reactants and/or products may
not be in standard states.
2
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2.      (a)     minimum energy
1
to start a reaction/ for a reaction to occur/ for a successful collision
1
(b)     activation energy is high / few molecules/particles have sufficient
energy to react/few molecules/particles have the required
activation energy
(or breaking bonds needs much energy)
1
(c)     molecules are closer together/ more particles in a given volume
1
therefore collide more often
1
(d)     many
1
more molecules have energy greater than activation energy (QoL)
1
(e)     speeds up a reaction but is chemically unchanged at the end
1
(f)      increases the surface area
1
[9]

3.    (a)    (If any factor is changed which affects an equilibrium), the (position of) equilibrium will shift / move so as to oppose / counteract the change.
Must refer to equilibrium
Ignore reference to “system” alone
A variety of wording will be seen here and the key part is the last phrase
OR
(When a system / reaction in equilibrium is disturbed), the (position of) equilibrium shifts / moves in a direction which tends to reduce the disturbance
An alternative to shift / move would be the idea of changing / altering the position of equilibrium
1
(b)    (i)      M1 
A substance that speeds up the reaction / alters the rate but is chemically unchanged at the end / not used up
Both ideas needed for M1
Credit can score for M1, M2  and M3 from anywhere within the answer
M2 
Catalysts provide an alternative route / alternative pathway / different mechanism
M3 
that has a lower activation energy / Ea
OR
lowers the activation energy / Ea
3
(ii)     (Time is) less / shorter / decreases / reduces
Credit “faster”, “speeds up”, “quicker” or words to this effect
1
(iii)    None
1
(c)     (i)      R
1
(ii)     T
1
(iii)    R
1
(iv)    P
1
(v)     Q
1
[11]

4.         (a)     Saturated − single bonds only / no double bonds
1
Hydrocarbon − contains carbon and hydrogen (atoms) only
1
(b)     C16H34 + 16.5O2  16CO + 17H2O
Allow multiples
1
(c)     (On combustion) SO2 produced
Allow equation to produce SO2. Ignore sulfur oxides.
1
Which causes acid rain
If formula shown it must be correct
M2 is dependent on M1. But if M1 is sulfur oxides, allow M2.
For M2 allow consequence of acid rain or SO2.
Ignore greenhouse effect and toxic
1

(d)     (i)      C16H34  C8H18 + C2H4 + 2C3H6
Allow multiples
1
(ii)     polypropene / propan(-1 or 2-)ol / propane(-1,2-)diol / isopropanol / propanone / propanal
Accept alternative names
Ignore plastic and polymer
1
(iii)    

1
(e)     

Allow any unambiguous representation
1
(f)     2,4-dichloro-2,4-dimethylhexane
Only but ignore punctuation
1
[10]

5.      (a)     (i)      M1 pentan-3-one only
1
M2 CH3CH2CH2COCH3
(insist on C=O being drawn out)
(penalise use of C3H7)
1
(ii)     aldehyde         (CH3)2CHCH2CHO
1
ketone             (CH3)2CHCOCH3
1
(insist on a clear structure for the C=O of the functional groups, but do not be too harsh on the vertical bonds between carbon atom son this occasion)
(If both structures correct, but wrong way around, award one mark)
(ignore names)
(b)     (i)      CH3CH2CH2CH2CHO + [O] → CH3CH2CH2CH2COOH
(accept C4H9CHO going to C4H9COOH)
(insist on a balanced equation – for example do not credit [O] over the arrow alone)
1
(ii)     pentanoic acid
(credit pentan–1–oic acid)
1

(c)     (i)      CH3CH2CH2CH2CH2OH OR pentan–1–ol
(If both a structure and a formula are given, credit either correct one of these provided the other is a good, if imperfect, attempt)
1
(ii)     Primary
(credit 1o or 1)
1
[8]
 
6.      (a)     (i)      Electrophilic addition
(Both words required)
1
(ii)     M1 the reaction to form 1-bromopropane goes via the primary
carbocation OR 1o carbocation
         OR via 
M2 primary carbocations are less stable than secondary carbocations
(Credit converse arguments for M1 and M2 i.e. the reaction to form 2-bromopropane goes via the secondary carbocation , M1, and secondary carbocations are more stable than primary carbocations, M2)
(Accept the use of “carbonium ions” as an alternative to carbocation)
1
(b)     M1 NaOH OR KOH OR correct name
1
M2 aqueous or solution in water (ignore heat, reflux etc.)
(Penalise M1 for hydroxide ion alone, but mark on and credit M2)
(Credit M2 ONLY for H2O as reagent and heat / warm / T=50 to 100oC)
(NaOH(aq) scores M1 and M2 provided it is not contradicted)
(Penalise M2 if NaOH(aq) followed by concentrated or ethanol)
(Penalise M1 and M2 if followed by acid)
1
(c)     Ethanolic OR alcoholic OR CH3CH2OH / CH3OH solvent OR
aqueous ethanol/alcohol
OR higher temperature (must be comparative)
(Ignore heat or heat under reflux)
(Credit part (c) independently from part (b))
(Penalise “ethanoic”)
1

(d)     (i)      Secondary OR 2o
1
(ii)     
         M1 arrow from double bond to H of H – O bond
M2 arrow from bond to oxygen atom to show H – O bond breakage
M4 arrow from lone pair of electrons to carbon atom of carbocation
(Penalise M1 if arrow goes to H2SO4 or to formal positive charge on H, but ignore partial charges on sulphuric acid unless wrong)
(Credit M2 for H+ ion)
(For M4, accept negative charge anywhere on the ion)
4
(iii)     Catalyst ONLY
(Ignore homogeneous, heterogeneous)
1
[12]
 
7.	Measure volume of gas / mass loss
If ‘measure concentration’ must explain how to score mark
1
At (regular) time intervals
Ignore references to temperature
Accept ‘against time’
Do not accept ‘with time’ or ‘over time’ on its own
1
[2]

8.      Acidified potassium dichromate(VI)
1
Turns green with propan-2-ol and propanal
1
No reaction with hexene and 1-bromopropane
1
Tollens with propan-2-ol and propanal
1
only propanal gives silver mirror
1
Bromine water
1
Decolourised by hexane
1
No reaction with 1-bromopropane
1
Warm NaOH followed by acidified AgNO3
1
White ppt with 1-bromopropane
1
[10]