1. Set 5 Marking Scheme :Manufactured Substances in Industry 2010
PAPER 2 : STRUCTURE
NO. Answer Marks
1(a) Haber Process 1
(b) N2 + 3H2 → 2NH3 1
(c) Iron 1
(d) Temperature, 450oC , Pressure 200 atm 1
(e) Ammonium sulphate 1
(f)(i) NH3 + CO2 → CO(NH2)2 + H2O 1
(ii) RMM urea = 60
% N = 2(14) x 100 1
60 1
= 46.6%
(g) 1.Blue precipitate soluble in excess ammonia solution 2
2.Forming dark blue solution
2(a)(i) Contact process 1
(ii) Haber Process 1
(b)(i) 2SO2 + O2 → 2 SO3 1
(ii) Vanadium(V) oxide 1
(c)(i) N2 + 3H2 → 2NH3 1
(ii) Temperature, 450oC , Pressure 200 atm 1
(d)(i) Ammonium sulphate 1
(ii) (NH4 )2SO4
(iii) RMM ammonium sulphate = 132
% N = 2(14) x 100 = 21.2 % 2
132
(e) Manufacture of detergents/ production of fertilizer/ manufacture of artificial fibres/ 1
manufacture of paint / leather tanning/ as electrolyte in car batteries
3(a) Large molecules made up of many identical repeating sub-units called monomers which 1
are joined together by covalent bonds.
(b) Monomer Polymer 4
Amino acid Protein
Glucose Starch
Ethene Polyethene
Isoprene Natural rubber
(c)
H H
| |
── C ── C ──
| |
H H n
(d)(i) PVC does not rust, iron will rust
(ii)
Cl
(e) Natural polymer – protein, starch, natural rubber
Synthetic polymer – polyethene, polychloroethene
Chemistry Perfect Score Module Form 4 2010 Marking Scheme Set 5 38

2. Set 5 Marking Scheme :Manufactured Substances in Industry 2010
PAPER 2: ESSAY
No. Answer Marks
4(a)(i) 1. pure metal atom have similar size and shape
2. arranged closely and form layers of atoms
3.when force is applied, layers of atoms slide on each other easily 3
(ii) 1. the atoms of the foreign metal added to pure metal have different size
2. these atoms distrupts the arrangement of the pure metal atoms
3. preventing the layers of metal from sliding on one another easily 3
(iii) 1. increase the strength and hardness of metal
2. prevent corrosion of metal
3. improve the appearance of metal and make it more attractive. 3
(b)(i) 1. aluminium is a pure metal
2. it is soft and not strong / cannot withstand compression 2
(ii) 1. duralumin
2. an alloy of aluminium that stronger and harder than aluminum. 4
3. can withstand compression
4. yet is light as aluminium
(iii) 1. tin and copper
2.stronger than tin 4
3. able to withstand corrosion
4. shinier surface than tin
20
5(a)(i) Large/long/giant/big chain smaller molecules/monomers made from joining of smaller 1
monomers.
Synthetic Monomers Uses
(ii) polymers
Polythene Ethene Plastic bags/ containers/ electrical
wiring
Polypropene Propene Piping / bottle crates/ carpets / car
batteries/ ropes
Polyvinyl Chloroethene/vinyl chloride Artificial leather/water pipes
Chloride
Perspex Methylmethacrylate/methyl Safety glass/reflectors/lens
2-methyl propenoate 6
Terylene Hexane-1,6-diol Clothing/sails/ropes
Nylon 1,6-diamine hexane Rope/clothing/carpets
Name of 2 synthetic polymers 2 marks
their are respective monomers 2 marks
2 uses
(b)(i) Formed by combining two or more different substances/ materials 2
That is better/stronger/superior /durable than the original component.
Composites material Uses
Reinforced Concrete Buildings / bridges/ oil platforms
Superconductors Magnetic energy-storage systems/ generators/
transformers/ computer parts
Fibre optic Telephone lines/ mobile phones/video cameras/
LAN
Fibre glass Household products: water storage tanks/
badminton rackets/small boats/skis/helmets
Chemistry Perfect Score Module Form 4 2010 Marking Scheme Set 5 39

3. Set 5 Marking Scheme :Manufactured Substances in Industry 2010
Photochromic glass Optical lenses/car windshields/windows in
buildings/ information display panels/ lens in 4
cameras/optical switches
Names of 2 composites material.
Respective use.
(c) 1. Sulphur dioxide gas / toxic waste dissolves in
rain / water to form acid rain /acid dissolved in
water.
2. Acid rain lowers the pH value of water / soil / air/
increases acidity.
3. Causing the death of plants.
4. Causing the death of aquatic creatures/fish
5. Causing damage to buildings / vehicles.
6. Decay of aquatic creatures by bacteria causing
7. The oxygen content in water to become less// (BOD)
increases. 7
8. The air pollution index reading will increase // air
quality become worse // causing the air pollution.
( choose any 7 above )
20
PAPER 3: STRUCTURE
No. Answer
6(a) Copper : 0.53 cm
Brass : 0.27
(b) Operation definition: if the dent is smaller, the material is harder
(c)
Manipulated variable The way to manipulate variable
Different type of material Repeat the experiment by using brass block to
replace copper block.
Responding variable What to observe in the responding variable
Diameter of the dent Observe the different diameter made by the
ball bearing on both copper and brass.
Fixed variable Way to maintain fixed variable:
Mass and height of the weight, size of the Use the same mass and height of the weight
steel ball bearing and size of the ball bearing in each experiment
(d) Bronze is harder than copper
Pure metal: iron, copper, aluminium
(e) Alloy : bronze, duralumin
Chemistry Perfect Score Module Form 4 2010 Marking Scheme Set 5 40

4. Set 5 Marking Scheme :Manufactured Substances in Industry 2010
No. Answer
7(a) Concrete is a composite material consisting of small stones and sand bound together by cement.
(b) Steel , steel is strong and high tensile stength
(c) Make pillars of high rise buildings
Make pillars of bridges
Make pillars of oil rig platform
(d) Is reinforced concrete stronger than concrete ?
(e)(i) Concrete and reinforce concrete
(ii) Hardness of the material
(iii) Height dropped of the weight, mass of the weight, size of the reinforced concrete
(f) The strength of the composite material is the ability of the material to withstand an impact (force).
The stronger the material, the heavier the weight required to break the material.
(g)(i) To make sun glasses / window panes / camera lenses
(ii) Silver nitrate solution is added to sodium chloride solution in a beaker and stirred.
The mixture is filtered and the precipitate rinsed with distilled water.
The precipitate is dried in an oven
PAPER 3 : ESSAY
8. (i) KK051201 - Problem statement
No. Rubric
[ Able to state the problem statement clearly and accurately]
Suggested answer
3
Does iron rust faster than steel?
[Able to state the problem statement slightly inaccurate]
Suggested answer
2
To study the rusting of iron and steel.
[Able to provide an idea of a problem statement]
1 Suggested answer
The rusting of iron and steel
8 (ii) KK051202 – Stating all variables
Score Rubric
[Able to state all the corresponding variables accurately]
Suggested answer
Manipulated variable : Iron and steel
3 Responding variable : Intensity of amount of blue colour
Fixed variables : Siza of nails, concentration of solutions
used, duration for rusting
2 [Able to state two corresponding variables accurately].
1 [Able to state any one corresponding variable correctly].
Chemistry Perfect Score Module Form 4 2010 Marking Scheme Set 5 41

5. Set 5 Marking Scheme :Manufactured Substances in Industry 2010
8 (iii) KK051202 – Statement of hypothesis
Score Rubric
[Able to state the relationship between manipulated variable and responding variable correctly]
Suggested answer:
3
Iron rusts faster than steel.
[Able to state the relationship between manipulated variable and responding variable but in
reverse direction]
2
Suggested answer:
Steel rusts faster than iron
[Able to state an idea of the hypothesis]
1 Suggested answer:
Iron and steel rust.
8. (iv) KK051205 – List of materials and apparatus
Score Rubric
[Able to list all materials and apparatus correctly]
Suggested answer
Materials
3 Iron nail, steel nail, jelly solution, potassium hexacyanoferrate(III) solution, Sandpaper,
Water.
Apparatus :Test tubes
[Able to list the basic materials and apparatus required]
Suggested answer
2 Iron nail, steel nail, potassium hexacyanoferrate(III) solution
Apparatus : Test tubes
[Able to provide an idea of materials and apparatus used]
1 Suggested answer
Iron nail, steel nail, jelly solution
8. (v) KK051204 – Experimental procedure
Score Rubric
[Able to state all experimental steps correctly]
Suggested answer
1. Rub nails with sandpaper until clean of rust.
2. Put iron nail in test tube 1 and steel nail in test tube 2.
3 3. Add jelly solution containing potassium hexacyanoferrate(III) into the test tubes until the
nails are completely immersed in it.
4. Leave the nails for three days.
5. After three days, observe the intensity of the blue colour.
[Able to provide 3 steps correctly to carry out the experiment]
2
Steps 2, 3 and 4
[Able to provide minimum of 2 steps correctly to carry out the experiment]
1
Steps 2 and 3
Chemistry Perfect Score Module Form 4 2010 Marking Scheme Set 5 42

6. Set 5 Marking Scheme :Manufactured Substances in Industry 2010
8. (vi) KK 0501-05 – Tabulation of data
Score Rubric
[Able to construct a table correctly containing the following elements]
- Columns and rows
- Observation for each test tube
Suggested answer
3
Test tube No. Intensity of blue colour
1
2
[Able to construct a tabulation of data containing the following elements]
- Rows and columns present
- Observation
Suggested answer
2
Test tubes Observation
[An idea of a tabulation of data ]
1
- Minimum of 2 rows and columns
Chemistry Perfect Score Module Form 4 2010 Marking Scheme Set 5 43