Section A (Answer ALL questions.)
1. A student suggested the following immediate actions to deal with three domestic accidents.
However, these actions are considered inappropriate.
Accident Suggested action
(1) Some drain cleaner, which contains mainly concentrated sodium hydroxide solution, is spilt onto the hand.
(2) During cooking, some oil in a cooking pan catches fire.
Use vinegar to neutralize the sodium hydroxide solution left on the hand.
Use water to put out the fire.
(3) Leakage of town gas occurs in a kitchen Turn on an exhaust fan in the kitchen to remove the town gas.
In each case, explain why the action is inappropriate and suggest a proper action.
(a large quantity of) heat/energy and thus will cause burning of the skin.
(DO NOT accept damage/hurt/corrosion to skin)
(8 marks)
1. (1) The reaction between c. NaOH and vinegar is (highly) exothermic/releases 1
1
Proper treatment: Wash the hand with (large amount of) water/add plenty of water/pour water onto the hand. 1
(2) The oil will continue to burn because oil floats on water/The fire will spread by pouring water.
Proper treatment: cover the pan with a wet blanket/wet cloth/the lid of the pan/fire blanket extinguish the fire with carbon dioxide/foam/dry
1 powder/BCF (type fire) extinguisher/sand (bucket)
(DO NOT accept fire extinguisher alone.)
(3) Turning on the exhaust fan may produce a spark which may cause an explosion/the ignition of the town gas/cause a fire.
Proper treatment: turn off the gas supply/open windows to let out the town gas/inform the Town gas company (police/fire services) via an outside telephone
2. The relative molecular mass of an alkanol X is 60.0. X contains 60% of carbon by mass.
(a) Calculate the number of moles of carbon in one mole of X and hence deduce the molecular formula of X .
1
1
1
1
(b) Draw ONE possible structure of X and give its systematic name.
(Relative atomic mass: C = 12.0)
(5 marks)
2. (a)
1 mole of X contains
12
= 3 moles of C
1
The general formula of alkanol is
C n
H
2 n

1
OH processes an alkyl group and a hydroxy group
(
C n
H
2 n

2
O
)/an alkanol
1
∴ molecular formula of X is
C
3
H
7
OH
(
C
3
H
8
O
)
1
(b)
H
H
C
H
H
C
H
H
C
H
OH
1+1
/ †propan-1-ol/1-propanol
H
H
C
H
C
H
C H
(1+1) or,
H
†correct spelling
OH H
/
( CH ) CHOH
†propan-2-ol/2-propanol
3. 'Fossil fuels' such as petroleum and coal constitute the world's major source of energy.
However, many countries have been developing alternative energy sources.
(a) Why are petroleum and coal called 'fossil fuels'?
(b) Give TWO reasons why it is necessary to develop alternative energy sources.

(c) Nuclear power is used as an alternative to fossil fuels in many countries. Suggest
ONE advantage and ONE disadvantage of using nuclear power.
(d) Suggest ONE energy source, other than nuclear power, that can be used as an alternative to fossil fuels.
(6 marks)
3. (a) Petroleum and coal were formed from the remains (dead/decayed bodies) of living organisms (animals and plants) that lived millions (thousands) of years ago/long time ago/many years ago.
(b) Any TWO of the following:
The reserve of fossil fuel is limited/may be used up/is non-renewable energy source
The price of fossil fuel is controlled by countries which have large reserve of these fuels. For economic and political reasons, countries which do not have reserve of fossil fuels have to develop other energy sources.
Burning of fossil fuels produces a lot of air pollutants
Burning of fossil fuels can cause global warming/greenhouse effect
(c) Advantage: in the long run, nuclear power is cheaper/can produce a large quantity of energy/production of nuclear power produces less air pollutants/nuclear power is a clean energy source.
Disadvantage: Leakage of radioactive source is disastrous (harmful/may cause cancer)/difficult to treat the waste/initial setting up of the plant is expensive. 1
(d) Solar energy/hydroelectric power/geothermal energy/tidal power/wind power/power from biomass. 1
For questions 4 and 5, candidates are required to give paragraph-length answers. 3 of the
1
(1)
(1)
(1)
(1)
1
2 marks for each of these two questions will be awarded for the effective communication of knowledge in Chemistry.
4. Briefly describe an experiment, using the following apparatus and materials, to show that air is necessary for the rusting of iron.
2 test tubes, a test tube holder, a Bunsen burner,
2 clean iron nails, paraffin oil and tap water
(8 marks)
4. Chemical Knowledge (5 marks)
Boil some tap water in a test tube to expel/remove any dissolved oxygen (air)
Place one nail in a test tube containing some tap water (Tube 1) and the other nail in a test tube containing the boiled water (Tube 2)
Add some paraffin oil on top of the boiled water in tube 2 to prevent air to dissolve into the water/to get in contact with the nail
After a few days/some time, rusting occurs/reddish solid can be seen in tube 1/no change in tube 2.
(Award zero marks for the observation, if it is contradictory to the procedure.)
Effective communication (3 marks)
General guidelines for marking effective communication:
(i) The mark for effective communication should relate to the candidate's knowledge in chemistry. A candidates who wrote a paragraph which is totally unrelated to the question should deserve zero mark both in chemical knowledge and in effective communication.
(ii) The table below illustrates the relationship between the mark for chemical knowledge and the maximum mark for effective communication.
1
1
1
1
1 mark for chemical knowledge
4 or above
3 or below maximum mark for effective communication
3
2 points to be considered in paragraph (iii) below
(A), (B) and (C)
(B) and (C)
(iii) The three marks for effective communication are awarded as follows:
(A) the ability to present ideas in a precise manner, including the correct use of chemical terms (this mark should not be awarded to answers which contained a lot of incorrect/superfluous materials);
(B) the ability to present ideas in a systematic manner (i.e., the answer is
1

easy to follow);
(C) the ability to present answer in paragraph form and to express ideas using full sentence.
5. The following statement is found on a pack of cigarettes:
'CIGARETTE SMOKING IS HAZARDOUS TO HEALTH'
Explain the above statement by making reference to the effects on health of the different substances present in cigarette smoke.
(9 marks)
5. Chemical Knowledge (6 marks)
Cigarette smoke contains the following substances
(Any 3 of the substances below + their corresponding hazardous effects) carbon monoxide which is a (deadly) poisonous/toxic gas
3+3
(1+1) or carbon monoxide combines with haemoglobin and thus reduces the oxygen carrying capacity of (red) blood (cell) tar/polycyclic aromatic hydrocarbons (PAHs) which is suspected to be carcinogenic/can cause the death of cilia/inflammation (damage) of bronchial
1
1 tubes/cause damage to lung tissue nicotine can cause people to addict to it/the constriction (shrinking/contraction) of blood vessels and make heart and lungs work harder/stomach ulcers/is toxic/can upset the function of the nervous system
(DO NOT accept nicotine affect the nervous system/has a bad smell) particulates/particles/soot cause damage of the respiratory system/contain substances which are carcinogenic
Effective communication (3 marks)
General guidelines for marking effective communication:
(i) The mark for effective communication should relate to the candidate's knowledge in chemistry. A candidates who wrote a paragraph which is totally unrelated to the question should deserve zero mark both in chemical knowledge and in effective communication.
(ii) The table below illustrates the relationship between the mark for chemical knowledge and the maximum mark for effective communication.
(1+1)
(1+1)
(1+1) mark for chemical knowledge
4 or above
3 or below maximum mark for effective communication
3
2 points to be considered in paragraph (iii) below
(A), (B) and (C)
(B) and (C)
(iii) The three marks for effective communication are awarded as follows:
(A) the ability to present ideas in a precise manner, including the correct use of chemical terms (this mark should not be awarded to answers which contained a lot of incorrect/superfluous materials);
(B) the ability to present ideas in a systematic manner (i.e., the answer is easy to follow);
(C) the ability to present answer in paragraph form and to express ideas using full sentence.
END OF SECTION A
Section B (Answer any THREE questions.)
6. (a) The table below lists the oxidation number of iron in two compounds:
Compound Iron(II) sulphate Iron(III) sulphate
Oxidation number +2 +3
(i) (1) What would be observed when sodium hydroxide solution is added to iron(II) sulphate solution? Write an ionic equation for the reaction involved.
(2) Explain whether this reaction is a redox reaction.
(ii) When iron(II) sulphate solution is mixed with dilute sulphuric acid and a small amount of a purple solution, a reaction occurs and the oxidation number of iron changes from +2 to +3.
(1) Suggest what the purple solution may be.
1
1
1

(2) What would be observed in this reaction? Write an ionic equation for the reaction involved.
(iii) When iron(II) sulphate solution reacts with an element X , the oxidation number of iron changes from +2 to 0.
(1) Suggest what X may be.
(2) What would be observed in this reaction? Explain whether iron(II) sulphate solution acts as a reducing agent or an oxidizing agent in this reaction.
(10 marks)
6. (a) (i) (1) (dirty) green precipitate/solid is formed
Fe
2


2 OH


Fe OH
1
1
(2) No, because the reaction does not involve any change in oxidation no./there is no transfer of electron(s)
(ii) (1) The purple solution is (potassium) permanganate/ manganate(VII)/
MnO
4

ions
(2) The solution changes colour from purple/(pale) green to yellow/brown
(DO NOT accept colourless)
5 Fe
2


MnO
4
 
8 H


5 Fe
3


Mn
2


4 H O
(iii) (1) Magnesium (Mg)/Zinc (Zn)/Aluminium (Al)
(2)
(DO NOT accept K, Na, Ca)
Any TWO of the following:
Mg/Zn/Al/metal dissolves.
Silvery (grey) powder deposits/ colour of solution becomes paler (colourless).
Iron(II) sulphate acts as an oxidizing agent because the oxidation no. of iron changes from +2 to 0/decreases/
Fe
2
 ions accept electrons
1
(b) A , B , C and D are four unlabelled bottles, each containing one of the following reagents:
2 M ammonia solution, 2 M ethanoic acid,
2 M hydrochloric acid, 2 M nitric acid
The following scheme is used to identify the four reagents:
1
2
(1)
(1)
1
1
1
1

Reagent in bottle
C and D
Add a piece of red litmus paper,
Does the red litmus paper turn blue?
yes no
Add copper turnings and warm the mixture,
Reagent in bottle A
Are brown fumes
evolved?
yes Reagent in bottle B no
Reagent in bottle
C and D
(i) What is the reagent in bottle A ? Explain why this reagent turns red litmus paper blue.
(ii) What is the reagent in bottle B ? Write a chemical equation for the reaction between this reagent and copper turnings, and a chemical equation for the formation of the brown fumes.
(iii) (1) Suggest a test to distinguish between the reagents in bottles C and D .
(Smelling the reagents is NOT an acceptable answer.)
(2) State the observable change in this test and explain your answer.
(8 marks)
6. (b) (i)
A is 2 M ammonia/ 2M
NH
3
Ammonia ionizes in water to give OH

which turns red litmus paper blue/ammonia solution is alkaline
(ii)
B is 2 M nitric acid/ 2M
3 Cu

8 HNO or 3
Cu

8 H
3



2
3 (
NO
3

HNO

3 Cu
2 if
NO

O
2

Cu

4 HNO
2
3
NO
2

Cu ( or
Cu

4 H
 
2 NO
3

NO
3

)
Cu
2
2


3
2

2


2
NO

4 H O
NO
2
2

2 NO
NO
2



2
2
4
H
H O
2
H
O
2
O
(iii) (1) Add a piece of pH paper/a few drops of universal indicator to the reagent
(2) HCl will give a lower pH/a deeper red colour because HCl
1
1
1
1
(1)
1
(1)
(1) ionizes to a greater extent than
CH
3
COOH
/HCl is a stronger
1
1
1

acid/HCl has a higher concentration of or (1) Add a piece of Mg ribbon/Zn granules/
CaCO
3
( s )
to the reagent
(2) HCl will give gas bubbles at a faster rate because HCl ionizes to
(1) a greater extent than
CH
3
COOH
/HCl is a stronger acid/HCl
(1)
(1) has a higher concentration of or (1) Add
AgNO
3
( aq )
/
Pb ( CH
3
COO )
2
( aq )
to the reagent
(1)
(2) HCl will give a white precipitate while
CH
3
COOH
not,
(1)
(1) because
AgCl / PbCl
2 is insolube in water or (1) Allow the vapour of the reagent to react with
NH
3
( g ) (1)
(2) HCl will give dense white fume while
CH
3
COOH
not
(1)
(1)
(2) because
NH
3
( )
NH
4
Cl ( s )
is formed when HCl(g) reacts with or (1) Measure the electrical conductivity of the solutions
HCl has a higher conductivity because HCl ionizes to a greater extent than
CH
3
COOH
/HCl is a stronger acid/HCl has a
(1)
(1)
(1)
(2) higher concentration of or (1) Measure the pH of the solutions with a pH meter
HCl has a lower pH because HCl ionizes to a greater extent than
CH
3
COOH
/HCl is a stronger acid/HCl has a higher
(1)
(1)
(1) concentration of or (1) Warm the reagent with ethanol in the presence of a few drops of
(1) c.
H
2
SO
4
(2)
CH
3
COOH
gives a pleasant smell while HCl not because an
(1)
(1) ester is formed when reacts with
(1 mark for a correct test; 1 mark for observation; 1 mark for explanation. Accept any reasonable answer.)
7. (a) The boxes below show some information about two atoms, hydrogen (H) and deuterium (D):
Mass number 1 Mass number 2
H D
Atomic number 1 Atomic number 1
(i) Suggest a term to indicate the relationship between a hydrogen atom and a deuterium atom.
(ii) State the number of neutrons in a deuterium atom.
(iii) Deuterium reacts with oxygen in the same way as hydrogen.
2 D
2
( )

O
2
( )

2
Δ H is negative
The product of the reaction is known as 'heavy water'.
(1) Explain why deuterium reacts with oxygen in the same way as hydrogen.
(2) Draw the electronic structure of 'heavy water', showing electrons in the outermost shells ONLY .
(3) What is meant by ' Δ H is negative'?
(4) What is the formula mass of 'heavy water'?
(5) 100 cm
3
of deuterium and 100 cm
3
of oxygen, both measured at room temperature and pressure, are allowed to react. Calculate the mass of
'heavy water' produced.
(Relative atomic mass: O = 16.0;
Molar volume of gas at room temperature and pressure = 24.0 dm
3
)
(9 marks)

7. (a) (i) isotope
(ii) One/1
(iii) (1) H and D have the same electronic structure (arrangement/ configuration)
(DO NOT aceept H and D have same no. of electrons in their outermost shells)
(2)
D O D
(3) The reaction is exothermic/gives out heat/releases energy
(4) Formula mass = 2 + 2 + 16
(5)
2 D
2
( )

O
2
( )
= 20

2
In the mixture, no. of moles of
D
2 = no. of moles of
O
2

24
O
2 is in excess ∴ no. of moles of produced
Mass of produced

.
24

20
= 0.0833 g (0.083-0.084 g)
(Also accept 0.08 g; deduct 1 mark for wrong/no unit)

24
(b) The flow diagram below shows the three key stages involved in the production of polypropene bottles from crude oil.
1
1
1
1
1
1
1
1
1
(i) What is the process involved in obtaining heavy oil from crude oil in Stage I?
(ii) (1) Draw the structure of monomer A .
(2) What are the TWO main processes involved in the production of monomer A from heavy oil in Stage II?
(iii) What are the TWO main processes involved in the production of polypropene bottles from monomer A in Stage III?
(iv) Suggest ONE reason why the disposal of polypropene wastes can cause pollution problems.
(v) Polypropene wastes can be recycled by melting and remoulding.
(1) What preliminary treatment of the polypropene wastes is required before recycling?
(2) Name ONE plastic which cannot be recycled by melting and remoulding.
(9 marks)
7. (b) (i) fractional distillation of crude oil 1
(ii) (1)
CH
3
H
C C
1
H H
/
CH CH

CH
2
(2) (catalytic) cracking of heavy oil separation/fractional distillation of the mixture to obtain propene
(iii) Monomer A (propene) is polymerised to give polypropene
1
1
1

polypropene is moulded/blow-moulded/injection moulded to give the polypropene bottle
(iv) Polypropene cannot be easily degraded by micro-organisms/the degradation of PP takes a long time/PP is non-biodegradable or, the incineration/burning of PP waste may produce toxic gases/air pollutants
(v) (1) Separating PP from other plastic wastes/cleaning the PP waste
(2)
†Urea-methanal
(accept correct name of any thermosetting plastics e.g. †phenolmethanal, †bakelite)
†correct spelling
(1)
(1)
1
8. (a) The table below lists some information about four nitrogen-containing compounds which may be used as fertilizers.
1
1
Compound Solubility in water at
25 ℃ / moldm

3
Cost per kg of compound / $
Cost per kg of nitrogen in the compound / $
NH
3
31.1 12.0
(
3
NH
4 2
SO
4
( NH ) HPO
4
26.8
5.8
4.4
20.0
15.0
141.0
(i) Explain why nitrogen is essential for the growth of plants.
(ii) Calculate the value of x .
14.6 x
70.7
664.7
(iii) Suggest TWO reasons why farmers do not prefer using ammonia (gas or solution) directly as a fertilizer.
(iv) The growth of some plants such as turnips requires a large amount of nitrogen.
Which of the four compounds is the most suitable for use as a fertilizer for these plants? Explain your answer.
(Relative atomic masses: H = 1.0, N = 14.0, O = 16.0)
(8 marks)
8. (a) (i) Nitrogen is used in the plant to produce amino acids/proteins/cytoplasm/chlorophyll/nucleotide
(ii) formula mass of 3 = 14 × 2 + 1 × 4 + 16 × 3
1
1 fraction by mass of N in
= 80

28
3
80 x

20

80
28
= 57.1 (57.14)
1
1
(iii) Any TWO of the following:
Ammonia is a toxic gas/has irritating/unpleasant/pungent/bad smell
It makes the soil (too) alkaline for plant glowing
It is difficult to transport/handle/stored/can easily vaporize
(DO NOT accept ammonia can be wasted away by water.)
(iv) Ammonium nitrate because apart from ammonia, ammonium nitrate has a low cost per kg of nitrogen/has high solubility in water and hence can easily be absorbed by plants
2
(1)
(1)
(1)
1
1
(b) The diagram below shows a ten dollar coin which is made of two alloys, X and Y .
(i) (1) What is an alloy?
(2) State TWO properties of an alloy that make it suitable as a coinage metal.

(ii) When compared with using only one alloy, using two alloys to make the ten dollar coin has certain advantages and disadvantages. Give ONE advantage and
ONE disadvantage of using two alloys to make the coin.
(iii) When alloy X is heated with concentrated sulphuric acid, a bluish-green solution is formed and a colourless gas is evolved.
(1) Suggest ONE metal that may be present in X . Explain your answer.
(2) What is the colourless gas? Suggest a chemical test for the gas.
(10 marks)
8. (b) (i) (1) An alloy is a (solid) mixture of two or more elements of which at least one is a metal/a (solid) mixture of metals
(2) Any TWO of the following:
It should be soft enough/easy to be minted/stamped (moulded)
It should be corrosion resistant/chemically unreactive/long
1
2
(1) lasting/durable
It should be hard enough to resist it from wearing away
(ii) Advantage: more attractive (beautiful)/prevent forgery/can easily be distinguished from other coins
Disadvantage: difficult to make/more expensive/possibility of X detaching from the coins
(Accept any reasonable answer)
(iii) (1) Copper/Cu/nickel/Ni
Copper(II)/ Cu
2

/nickel(II)/ Ni
2

ions are bluish-green in colour.
(Accept any metal which forms blue/green ions upon reaction with c.
H SO
4 )
(2) sulphur dioxide/
SO
2
It can turn acidified (potassium) dichromate solution from orange to green or it can turn acidified (potassium) permanganate solution from purple to colourless
1
1
1
(1)
(1) or it can turn bromine water from brown (yellow/orange) to colourless.
(DO NOT accept litmus paper test.)
(1)
(1)
9. (a) The diagram below shows a longitudinal section of a fire extinguisher. When the extinguisher is being used, solution X is allowed to mix with the sodium hydrogencarbonate solution and a reaction immediately occurs. A jet of aqueous solution will then be forced out of the extinguisher.
(1)
(1)
1
1
1
1
(i) Suggest what solution X may be.
(ii) (1) Write an ionic equation for the reaction between solution X and the sodium hdyrogencarbonate solution.
(2) Explain why a jet of aqueous solution is forced out of the extinguisher.
(iii) The diagram below shows a 'fire triangle'.

heat fuel Y
(1) Complete the 'fire triangle' by writing a suitable word for ' Y '.
(2) Using the concept of 'fire triangle', give TWO reasons why the fire extinguisher mentioned previously can be used to put out a fire.
(iv) In the Mass Transit Railway, bromochlorodifluoromethane (BCF) fire extinguisher, rather than the type of fire extinguisher shown on the previous page, is used to put out electrical fires.
Suggest ONE advantage and ONE disadvantage of using a BCF fire extinguisher to put out electrical fires.
(8 marks)
9. (a) (i)
(ii)
Sulphuric/hydrochloric acid/
H SO
4 /HCl
(DO NOT accept weak/concentrated acids)
(1)
HCO
3


H

 
2
(2) The carbon dioxide produced builds up a pressure in the extinguisher and force out the jet of aqueous mixture
(iii) (1) oxygen/oxidant/air
(2) The aqueous solution (water) has a cooling effect/can remove the heat
Carbon dioxide/aqueous solution (water) can cut off the supply of air/oxygen
(iv) Advantage: BCF does not conduct electricity
Disadvantage: BCF is toxic (poisonous)/BCF decomposes on heating to give irritating, corrosive fumes/BCF can cause depletion of ozone
(DO NOT accept BCF is harmful)
1
1
(b) A student carried out a copper-plating experiment in the laboratory using the set-up shown below:
1
1
1
1
1
1
(i) Explain why copper(II) sulphate solution can conduct electricity.
(ii) What would be observed at the carbon anode during the experiment? Write a half equation for the reaction involved.
(iii) In the copper-plating industry, a metal is used as the anode instead of carbon.
What is this metal? Explain your answer.
(iv) In a copper-plating factory, the waste water is treated with sodium hydroxide solution to remove the copper(II) ions present before discharge.
(1) Suggest TWO reasons why it is necessary to remove the copper(II) ions from the waste water before discharge.
(2) 20.0 dm
3
of a sample of waste water require 3.5 dm
3
of 8.0 M sodium hydroxide solution for complete removal of the copper(II) ions present.
Calculate the concentrations, in moldm

3
, of copper(II) ions in the sample.
(10 marks)
9. (b) (i) The solution contains mobile ions
(ii) A colourless gas (bubbles) is evolved
4 OH


O
2

2 H
2
O

4 e

1
1
1

(iii) Copper/Cu
During the copper-plating process, the copper in the anode is oxidized/changed/converted to give or,
Cu
 maintained
Cu
2


Concentration of
2 e

Cu
occurs at anode
Cu
2

2

ions
ions in the electrolytic solution can be
(iv) (1) To recover copper metal/To reduce the loss of copper metal
Cu
2

ions can cause water pollution/death of (harmful to) marine lives
(2) 1 mol of Cu
2
 or, Cu
2


2
ions reacts with 2 mol of NaOH
OH


Cu OH
Concentration of Cu
2

ion

20
= 0.7 (M)

1
2
END OF PAPER
1
1
1
1
1
(1)
1
(1)
1