QUESTION 2 – Organic Preparations
Experiment
1. Preparation of
ethene gas and its
properties
2. Preparation of
ethyne gas and its
properties
3. Soap preparation
4. Steam distillation of
clove oil
5. Preparation of
ethanal and its
properties
6. Preparation of
ethanoic acid and its
properties
7. Paper and thin layer
chromatography
Years
Year
2009
2004
2012
2009
2003
2011?
2010
2006
2002
2011
2008
2005
WHAT:
Liquid evaporated (entered condenser)
Vapour was condensed (changed to liquid)
Returned to flask (6)
HOW:
 Allowed enough time to bring reaction
to completion
 Provide the activation energy
 Heating without loss of reactants by
keeping the reactants together
ANY ONE: (6)
(b)
(i) WHAT:
Clove oil (eugenol) (5)
2011?
2007
(ii) APPEARANCE: cloudy / milky / creamy /
emulsion (6)
2008
(iii) SUB: water (H2O, steam) (3)
(iv) IDEN: feature (3) explanation (3)
QUESTION 2
2011
(a) IDENTIFY:
Preparation of soap or preparation of ethanoic
(acetic) acid (CH3COOH) (6)
DRAW: flask with contents shown or labelled
2010
(a) WRITE: Propane-1,2,3-triol (5)
(b)
WHY:
 To bring reaction to completion.
 To allow time (provide energy) for
reaction to complete.
 To maximise the yield of soap.
 To heat without loss of ethanol. (6)
NAME: Base hydrolysis or saponification (3)
WHAT: Solvent (3)




Anti -bumping granules
Condenser in correct position
Correct flow of water clearly indicated
Labelled or identifiable source of heat
(4 × 3)
(c) (i): DESCRIBE:
 Diagram showing flask with condenser in
position for distillation .
 Thermometer (heat with water bath,
distill at 78°) and heat source.
(2 × 3)
 use tongs or gloves
ANY THREE: (3 x 3)
(d) GIVE: calcium carbide or CaC2 (3)
DESCRIBE: grey solid (3)
[At least one correct label required]
[No diagram – lose 3 marks]
(ii) ISOLATED:
 Reaction mixture added to brine
(saturated sodium chloride solution) (3)
 Precipitated soap got by filtration (3)
(iii) PURIFIED:
Wash with brine or wash with water (6)
DRIED: oven (3)
(d) YIELD
(e) WHAT: double or triple carbon-to-carbon
bond present (3)
TEST:
 Add bromine water the gas in a test
tube, stopper, shake.
 Decolorises (changes from red to
colourless)
or
 Acidified potassium manganate(VII)
soln goes from pink to colourless
(3) +(3)
(f) WHAT: ethene less luminous (smoky, sooty)
(3)
WRITE:
C2H4 + 3O2 → 2CO2 + 2H2O
FORMULAS (3) BALANCING (3)
(g) GIVE:
(i) ethene: manufacture of polythene
ripening fruit (3)
(ii) ethyne: oxyacetylene flame for cutting
metals (3)
2008
(a) DESCRIBE:
Paper chromatography
2009
(a) GIVE: aluminium oxide Al2O3 (3)
WHAT: white (2)
(b) WRITE:
C2H5OH → C2H4 + H2O (3)
TERM: elimination [Accept “dehydration”] (3)
(c) STATE:
 Keep gas from flame
 Air-tight stopper
 Safety screen or glasses (goggles)
 Before heat removed take tube from
water





Apply mixture using capillary tube /
spotting on paper (3)
About 2 cm above eluent (3)
Place in tank with eluent (3)
Elute (solvent moves up) (3)
state or show separation of components
of mixture (3)
Thin-layer chromatography
(c) WHAT: do not mix or do not dissolve in
each other (3)
(d) NAME:
Clove oil (eugenol)
Whole cloves. (3 + 3)
(e) EXPLAIN:
Release of pressure (6)
(f) DESCRIBE: cloudy liquid / milky / white
(creamy) liquid (6)


Apply mixture using capillary tube (3)
About 2 cm above eluent* / just above
eluent* (3)
NAME: solvent extraction / shake with
suitable solvent (cyclohexane, ether, etc.) (3)

Place plate in tank with eluent* (3)
(g)

Elute (solvent moves up) (3)

State or show separation of components
of mixture (3)
Column chromatography
2007
(a) STATE:
 Add in dropwise
 Shake (stir) after each addition and
wait till the reaction subsides
 Cool reaction vessel ANY TWO: (2 × 4)
(b) DESCRIBE:
Orange (3) to green (3)
EXPLAIN: Cr6+ reduced to Cr3+ (3)


Dissolve mixture in eluent. (3)
Add mixture to column. (3)

Continue to add eluent* so that it flows
through column. (3)

Separation occurs and bands can be
seen. (3)

Collect components. (3)
(b) EXPLAIN: because each of the components
have different affinities for
(attraction for) the mobile and
stationary phases (6)
(c) PURPOSE:
To ensure oxidation does not stop at ethanal
(CH3CHO) but goes on to ethanoic acid
(CH3COOH) (3) and 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)
0.139 ethanol ( x 2/3) ≡ 0.09 mol dichromate /
0.1 mol dichromate ( x 3/2) ≡ 0.15 mol ethanol
(3)
(e) DESCRIBE:
Isolated by distillation (6)
(f) DESCRIBE: effervescence / fizzing (3)
WRITE:
Na2CO3 + 2CH3COOH → 2CH3COONa + H2O +
CO2
FORMULAS (3) BALANCING (3)
2006
(a) WHY:
 To speed up the reaction
 To drive reaction to completion
 To maximise (increase) yield (5)
TYPE: base hydrolysis or saponification (3)
(b) COMPLETE AND BALANCE:
3 C17H35COONa + CH2(OH)CH(OH)CH2OH (3)
(c) WHAT: As a solvent (3)
WHY: some soap will be dissolved in the
ethanol (3)
DESCRIBE:
(e) LOCATION:
(i) second product (glycerol); in the brine /
Buchner flask (3)
(ii) excess sodium hydroxide: in the brine /
Buchner flask (3)
(f) OBSERVE:
(i) immediate lather (suds, bubbles) (3)
(ii) scum / no lather (suds, bubbles) does not
easily form lather (3)
2005
(a) WHY: ethanal boils at about 21 °C (room
temp) (5)
(b) TWO FEATURES:
 If excess ethanol (or less dichromate
than is needed) (3) is used the process
stops at ethanol and doesn't go to
ethanoic acid. (3)
 Immediate distillation (removal) (3) of
ethanal prevents further oxidation (3)
 The oxidising agent (dichromate) in
funnel (3) means a small amount of
oxidising agent in flask (3)
Any two of the above.
(c) DESCRIBE:
Orange solution added to colourless liquid
becomes green (2 × 3)
ACCOUNT: Cr(VI) is reduced to Cr(III) (3)
Diagram should show correct labels (6)
d) DESCRIBE:
 Dissolve residue in minimum of boiling
(hot) water
 Pour onto brine (salt water)
 Filter
 Wash with more brine
(6) + (3)
(d) TEST:
Mix equal amounts of Fehling's 1 and Fehling's
2 (3)
Add ethanal and put test tube in hot (boiling)
water (3)
OBSERVE: brick-red (3) precipitate produced
(3)
2004
(a) FUNCTION: keeps ethanol at end of test
tube (5)
IDENTIFY: aluminium oxide Al2O3 (3)
DESCRIBE: white powder (solid) (3)
(b) PRECAUTIONS:
 Keep gas away from flames (3) gas is
flammable (3)
 Air-tight stopper (3) stops ethene
escaping (3)
 Taking tube from water (3) to prevent
suckback (3)
 Tongs (3) prevent burns (3)
Any two of the above
(c) EQUATION:
C2H5OH→ C2H4 + H2O
(d) UNSATURATED: double or triple carbonto-carbon bond present (3)
TEST: add bromine water (solution) (3)
Red (3) to colourless (3)
(e) FLAME: yellow luminous flame (3)
EQUATION:
C2H4 + 3O2 →2CO2 + 2H2O
Formulas (3) Balancing (3)
2003
(a) X = water (4)
Y = calcium carbide CaC2 (4)
(b) Dark grey solid (3)
(c)
CaC2 + 2H2O →C2H2 + Ca(OH)2 (6)
(d) Observation : luminous sooty flame (3)
Equation:
2C2H2 + 5O2→ 4CO2 + 2H2O
FORMULAS (3) BALANCING (3)
(e) Test:
Bromine water (solution) (6)
Shake with a sample of the gas(6)
red to colourless(6)
(f) oxyacetylene flame for cutting metals (6)
2002
CHEM DIFF: animal saturated, vegetable
unsaturated (double bonds) (5)
(b) WHAT ELSE:
anti-bumping agent (6)
WHY REFLUX:
To boil (heat) (3) without losing volatile
material (ethanol) (3)
ETHANOL: solvent for lard (3)
(c) WHY REMOVE: some soap dissolved in
ethanol and yield reduced (6, 3)
(d) MINIMUM: to maximise soap precipitating
out (6)
BRINE: salt solution (water) (3)
(e) DESCRIBE: filter (6)
PRECAUTION: wash with brine (6)