2002 Question 2
(a)
(b)
(c)
CHEM DIFF: animal saturated (all single bonds) / vegetable unsaturated (double bonds)
WHAT ELSE: anti-bumping granules
WHY REFLUX: because reaction is slow or to complete reaction (6)
to boil (heat) (3) // without losing volatile material (ethanol) (3)
ETHANOL: solvent for lard
WHY REMOVE: easier to isolate soap OR avoid waste of ethanol / /
maximize yield (6, 3)
(d)
(e)
MINIMUM: to maximise soap precipitating out
BRINE: salt solution
DESCRIBE: filter
PRECAUTION: wash with icecold water
2003 Question 2
(a) X = water OR H
2
O Cancelling, including name with formula if either incorrect
Y = calcium dicarbide [CaC
2
] *Cancelling does not apply if name is correct but formula, though incorrect, has Ca and C only.
(b) grey lumpy solid
(c) CaC
2
+ 2H
2
O = C
2
H
2
+ Ca(OH)
2
(d) Observation : luminous sooty flame
Equation: C
2
H
2
+ 2½O
2
→
2CO
2
+ H
2
O FORMULAS (3) BALANCING (3)
(e) Test: reagent Br
2
(6) procedure shake with (6) observation decolourised (6)
Question not on syllabus so above answer taken – if answered as asked equation (3) name of organic product (3) C
2
H
2
+ Br
2
= C
2
H
2
Br
2
(3) dibromoethene (3) C
2
H
2
+ 2Br
2
=
(f)
C
2
H
2
Br
4
(3) tetrabromoethane (3) oxyacetylene flame (torch
– but not blowtorch)
2003 Question 9
(a) Aldehyde: CH
3
CH
2
CHO / C
2
H
5
CHO
(In expanded structure, correct bonds must be shown but Hs can be omitted.)
IUPAC: propanal [Accept propan-1-al]
Other:
Name:
CH
3
COCH
3
propanone / acetone [Accept propan-2-one]
Use: removing nail varnish OR solvent for paint
Which: propanal.
Acid: propanoic acid
(b) (i) Prevents explosions
Allow (3) for ‘safety’.
(ii) What: mixture of clove oil and water
Describe: cloudy* / milky (not ‘creamy’) / white / emulsion
*Allow only (3) if ‘cloudy’ given with anything other than ‘milky’, ‘white’ or ‘emulsion’
(iii) flavouring OR Local anaesthetic
.
2004 Question 2
(a) FUNCTION: keeps ethanol at end of test tube
IDENTIFY: aluminium oxide [Al
2
O
3
]
DESCRIBE: white powder
(b) PRECAUTIONS: Must be matched first precaution (3) explanation (3); second precaution (3) explanation (3) keep gas away from flames (3) risk of explosion (3) safety screen (glasses) (3) risk of explosion (3) disconnecting tube (3) to prevent suckback (3) tongs (heat resistant gloves) (3) prevent burns (can be inferred here) (3)
(c) Al
2
O
3
EQUATION: C
2
H
5
OH = C
2
H
4
+ H
2
O
(6)
(4)
(4)
(3)
(3)
(6)
(3)
(3)
(6)
(3) +(3)
(6)
(6)
(5)
(3)
(3)
(12)
(6)
(5)
(6)
(12)
(3)
(9)
(6)
(3)
(6)
(6)
(4)
(4)
(3)
(6)
(3)
(6)
(18)

(d) UNSATD: double or triple bond present
TEST: add bromine water (3) // red [Accept ‘red-brown’ but not ‘brown’ ] (3) // to colourless OR decolourises ( not ‘goes clear’
) (3)
(e) FLAME: yellow OR luminous
EQUATION: C
2
H
4
+ 3O
2
→ 2CO
2
+ 2H
2
O Formulas (3) Balancing (3)
2004 Question 3.
(a) (i) so that crystals will form on cooling OR to maximise yield
(ii) insoluble : filtration of hot solution (3) remained on filter paper (3) soluble : filtration of recrystallised benzoic acid OR second filtration (3) passed through filter paper (funnel) (3)
(iii) let solution cool in ice-water [Accept check if melting point is sharp]
(iv) leave in warm place
(v) 90 % 2.25
× 100 = 90 (3)
(b)
2.5
(i) correct diagram with instrument for measuring temperature + one valid label
[e.g. melting point apparatus with thermometer or theile tube containing liquid + thermometer] // detail of setting up e.g. [ sample in melting point tube for melting point apparatus and thiele tube -
Stated or labelled in diagram ] // method of heating *
[electrical in melting point apparatus - Can be shown on diagram
– even if unlabelled
] //
heat slowly (gently)* // * Accept only two from these three points observe (note) the substance as it is heated* // note temperature (range) at which it melts // FOUR POINTS: (6 + 3 x 3)
(ii) lower (3) melting over wider range of temperatures (3)
(iii) preservative (E2- -) OR disinfectant
2005 Question 2
(a) WHY: ethanal volatile
(b) TWO FEATURES: first feature (3) explanation (3); second feature (3) explanation (3) excess ethanol (3) stops at ethanal OR doesn't go to ethanoic acid immediate distillation (removal) (3) prevents further oxidation (3) dichromate in funnel (3) small amount of oxidising agent in flask (3)
(c) DESCRIBE: orange solution added to colourless liquid // becomes green
(2 × 3)
ACCOUNT: Cr(VI) / Cr
2
O
7
2is reduced to Cr(III) / Cr 3+ (3)
(d) TEST: mix equal amounts of Fehling's 1 and 2 (3) add ethanal and warm (3)
OBSERVE: brickred (accept orange/brown) (3) precipitate produced (3)
(e) MASS: 2.97 g [Accept 2.948

3.000 g]
8.94 g sodium dichromate 0.03 mol (3)
0.03 mol dichromate ≡ 0.09 mol ethanal (3)
0.09 mol ethanal 0.09 x 44 * 
3.96 g ethanal
[* addition must be shown for error to be treated as slip ]
75 % yield = 3.96 x 75 = 2.97 g (3) (3)
100
2006 Question 2
(a) WHY: to speed up the reaction OR to maximise yield
[Allow ‘ to prevent loss of vapour (ethanol, solvent) ]
TYPE: base hydrolysis / saponification [Accept substitution ]
(b)
(c)
COMPLETE: C
17
H
35
COONa + CH
2
(OH)CH(OH)CH
2
OH (3)
[ Accept without brackets ]
BALANCE: 3 C
17
H
35
COONa + CH
2
(OH)CH(OH)CH
2
OH (3)
WHAT: solvent (3)
WHY: easier to isolate (extract) soap OR to avoid waste of ethanol (3)
DESCRIBE: diagram showing any two from the box and one correct label
(3)
(3)
(3)
(15)
(3)
(9)
(3)
(6)
(5)
(12)
(6)
(3)
(5)
(12)
(3)
(12)
(12)
(5)
(3)
(6)
(6)
(6)

Bunsen or hot plate & thermometer (positioned correctly) / gentle heat (water bath,) // still head / distilling flask // condenser (sloping down, showing inlet & outlet for water) // collection in vessel (adaptor not required)
[Diagram with any two from the box and no correct label (3)]
[If no marks got for diagram, (3) may be given for ‘heat gently until 20 to 25cm 3 ethanol collected
’.
To get this (3) there must be a diagram of some sort.]
DESCRIBE: dissolve residue in minimum of boiling water /water // (3) pour onto brine // filter // wash with a little ice-water
POUR INTO BRINE (6) ONE OTHER POINT (3)
(12)
(e) (i) LOCATION: second product : in the filtrate OR Buchner flask
(ii) LOCATION: excess sodium hydroxide : in the filtrate OR Buchner flask
(f) (i) OBSERVE: immediate lather
(ii) OBSERVE scum OR no lather
2007 Question 2
(3)
(3)
(3)
(3)
(a) STATE: add slowly // stir after each addition / wait till reaction ceases // cool reaction vessel
ANY TWO: (2 × 4)
(b) DESCRIBE: orange (3) // to green (3)
EXPLAIN: dichromate (Cr
2
O
7
2
–
) reduced to chromium(III) (Cr 3+ ) (3)
(c) PURPOSE: to speed up reaction (oxidation) // to ensure complete oxidation to ethanoic acid //to heat without loss of vapour (product) ANY TWO: (2 × 3)
(d) SHOW: mass of ethanol = 8.0 x 0.80 = 6.4 g (3) moles of ethanol = 6.4 ÷ 46* =
0.139 (0.14) mol (3) moles dichromate = 29.8 ÷ 298* = 0.1 mol (3) [* addition must be shown for error to be treated as slip.
]
0.139 ethanol (x 2/3) ≡ 0.09 mol dichromate OR 0.1 mol dichromate ( x 3/2) ≡ 0.15 mol ethanol (3)
(8)
(9)
(6)
(12)
(e) DESCRIBE: isolated by distillation (or distillation diagram) (6)
(f) DESCRIBE: fizzing OR bubbling (3) (6)
WRITE: Na
2
CO
3
+ 2CH
3
COOH
→
2CH
3
COONa + H
2
O + CO
2
FORMULAS (3) BALANCING (3)
2008 Question 2
(a) DESCRIBE: Paper chromatography [Lid not required in diagram.] spotting on paper (3) [Some description of application required.] just [2 cm] above solvent [eluent] (3) place in suitable container with eluent (3) solvent moves up (3) state or show separation of components of mixture (3)
(15)
(b)
(c)
(d)
(e)
(f)
(g)
EXPLAIN: diff. adsorbance on mobile and stationary phases
WHAT: do not mix
NAME: name // plant material clove oil // cloves [Correct order not required.]
EXPLAIN: avoids explosion
[allow 3 marks for ‘safety’ ]
DESCRIBE: white (creamy) liquid [Allow 3 marks for “ emulsion”.]
NAME: solvent extraction (cyclohexane, ether, etc.) [Allow 3 marks for mention of ‘cyclohexane’ etc. without qualification]
CALCULATE: 1.25 % 0.25/20 (3) ×100 = 1.25 (2)
2009 Question 2
(a)
(b)
(c)
GIVE: aluminium oxide / alumina / Al
2
O
3
(3)
WHAT: white (2)
WRITE: C
2
H
5
OH = C
2
H
4
+ H
2
O (3)
TERM: elimination
[Accept “dehydration”] [Cancel with second (incorrect) reaction type]
(3)
STATE: keep gas from flame / air-tight stopper / secure assembly / don’t use first gas jar // safety screen / glasses (goggles) / protective clothing / tie hair back //
(6)
(3)
(2 x 3)
(6)
(6)
(3)
(5)
(5)
(6)
(9)

(d)
(e)
(f)
(g) before heat removed take tube from water / disconnect tube / dismantle apparatus // use tongs / gloves // avoid inhaling glass wool / wear mask ANY THREE: (3 x 3)
GIVE: calcium (II) dicarbide / calcium carbide / carbide / CaC
2
(3)
DESCRIBE: black / dark / grey / off-white / grey black / brown-grey / dirty solid (3)
[“Give” & “Describe” not linked]
WHAT: double (triple, multiple) carbon-to-carbon bond present / undergoes addition (3)
TEST: add bromine water / bromine soln. / Br2 / acidified KMnO4 soln (3) decolourises / changes to colourless
(not ‘clear’) (3)
[The two (3)s are not linked]
WHAT: ethene less (ethyne more) luminous (smoky, sooty) (3)
[Allow “ethene has yellow flame whereas ethyne’s is sooty (smoky)”]
[Accept ‘ethyne produces soot’; otherwise comparing ethyne with ethene is required and cannot be assumed.]
WRITE: C
2
H
4
+ 3O
2
= 2CO
2
+ 2H
2
O or C
2
H
2
+ 2 ½ O
2
= 2CO
2
+ H
2
O or
2C
2
H
2
+ 5O
2
= 4CO
2
+ 2H
2
O FORMULAS (3) BALANCING (3)
GIVE: (i) ethene : manufacture of polythene {poly(ethene), plastic, polymer)} / make ethane-1,2diol (ethylene glycol, antifreeze) / make polyester (terylene) / make chloroethene (vinyl chloride) / make PVC {polyvinylchloride, poly(chloroethene)} / make ethanol / make phenylethene (styrene) / make poly(phenylethene) {polystyrene} / ripening fruit (3)
[Allow “growth hormone”, “growth promoter”]
(ii) ethyne : oxyacetylene flame (torch – not blowtorch) / cutting metals / welding metals / make ethanal (propanone, propan-2-ol, polymers, plastics, pesticides) / fuel for lamps [ not
‘fuel’ on its own ] (3)
[
Do not accept general terms e.g. “medicine”, agriculture”,” industry”, in both above answers, but do not cancel them with an acceptable use.
]
(6)
(6)
(9)
(9)

2010

2011