Set 5 Marking Scheme :Manufactured Substances in Industry 2010

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1 Set 5 Marking Scheme :Manufactured Substances in Industry 00 PAPER : STRUCTURE NO. Answer Marks (a) Haber Process (b) N + H NH (c) Iron (d) Temperature, 50 o C, Pressure 00 atm (e) Ammonium sulphate (f)(i) (g) NH + CO CO(NH ) + H O RMM urea = 60 % N = () x = 6.6%.Blue precipitate soluble in excess ammonia solution.forming dark blue solution (a)(i) (b)(i) (c)(i) (d)(i) (iii) (e) Contact process Haber Process SO + O SO Vanadium(V) oxide N + H NH Temperature, 50 o C, Pressure 00 atm Ammonium sulphate (NH ) SO RMM ammonium sulphate = % N = () x 00 =. % Manufacture of detergents/ production of fertilizer/ manufacture of artificial fibres/ manufacture of paint / leather tanning/ as electrolyte in car batteries (a) Large molecules made up of many identical repeating sub-units called monomers which are joined together by covalent bonds. (b) Monomer Polymer 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 Cl (e) Natural polymer protein, starch, natural rubber Synthetic polymer polyethene, polychloroethene Chemistry Perfect Module Form 00 Marking Scheme Set 5 8

2 Set 5 Marking Scheme :Manufactured Substances in Industry 00 PAPER : ESSAY No. Answer Marks (a)(i). pure metal atom have similar size and shape. arranged closely and form layers of atoms.when force is applied, layers of atoms slide on each other easily (iii) (b)(i) (iii) 5(a)(i) (b)(i). the atoms of the foreign metal added to pure metal have different size. these atoms distrupts the arrangement of the pure metal atoms. preventing the layers of metal from sliding on one another easily. increase the strength and hardness of metal. prevent corrosion of metal. improve the appearance of metal and make it more attractive.. aluminium is a pure metal. it is soft and not strong / cannot withstand compression. duralumin. an alloy of aluminium that stronger and harder than aluminum.. can withstand compression. yet is light as aluminium. tin and copper.stronger than tin. able to withstand corrosion. shinier surface than tin Large/long/giant/big chain smaller molecules/monomers made from joining of smaller monomers. Synthetic polymers Monomers Uses 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 -methyl propenoate Terylene Hexane-,6-diol Clothing/sails/ropes Nylon,6-diamine hexane Rope/clothing/carpets Name of synthetic polymers marks their are respective monomers marks uses Formed by combining two or more different substances/ materials 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 0 6 Chemistry Perfect Module Form 00 Marking Scheme Set 5 9

3 Set 5 Marking Scheme :Manufactured Substances in Industry 00 Photochromic glass Optical lenses/car windshields/windows in buildings/ information display panels/ lens in cameras/optical switches Names of composites material. Respective use. (c). Sulphur dioxide gas / toxic waste dissolves in rain / water to form acid rain /acid dissolved in water.. Acid rain lowers the ph value of water / soil / air/ increases acidity.. Causing the death of plants.. 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. 8. The air pollution index reading will increase // air quality become worse // causing the air pollution. ( choose any 7 above ) 7 0 PAPER : STRUCTURE No. 6(a) (b) (c) (d) (e) Answer Copper : 0.5 cm Brass : 0.7 Operation definition: if the dent is smaller, the material is harder Manipulated variable Different type of material Responding variable Diameter of the dent Fixed variable Mass and height of the weight, size of the steel ball bearing Bronze is harder than copper Pure metal: iron, copper, aluminium Alloy : bronze, duralumin The way to manipulate variable Repeat the experiment by using brass block to replace copper block. What to observe in the responding variable Observe the different diameter made by the ball bearing on both copper and brass. Way to maintain fixed variable: Use the same mass and height of the weight and size of the ball bearing in each experiment Chemistry Perfect Module Form 00 Marking Scheme Set 5 0

4 Set 5 Marking Scheme :Manufactured Substances in Industry 00 No. 7(a) (b) (c) Answer Concrete is a composite material consisting of small stones and sand bound together by cement. Steel, steel is strong and high tensile stength 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 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 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 : ESSAY 8. (i) KK050 - Problem statement No. [ Able to state the problem statement clearly and accurately] Does iron rust faster than steel? [Able to state the problem statement slightly inaccurate] To study the rusting of iron and steel. [Able to provide an idea of a problem statement] The rusting of iron and steel 8 KK050 Stating all variables [Able to state all the corresponding variables accurately] Manipulated variable Responding variable Fixed variables [Able to state two corresponding variables accurately]. : Iron and steel : Intensity of amount of blue colour : Siza of nails, concentration of solutions used, duration for rusting [Able to state any one corresponding variable correctly]. Chemistry Perfect Module Form 00 Marking Scheme Set 5

5 Set 5 Marking Scheme :Manufactured Substances in Industry 00 8 (iii) KK050 Statement of hypothesis [Able to state the relationship between manipulated variable and responding variable correctly] : Iron rusts faster than steel. [Able to state the relationship between manipulated variable and responding variable but in reverse direction] : Steel rusts faster than iron [Able to state an idea of the hypothesis] : Iron and steel rust. 8. (iv) KK0505 List of materials and apparatus [Able to list all materials and apparatus correctly] Materials Iron nail, steel nail, jelly solution, potassium hexacyanoferrate(iii) solution, Sandpaper, Water. Apparatus :Test tubes [Able to list the basic materials and apparatus required] Iron nail, steel nail, potassium hexacyanoferrate(iii) solution Apparatus : Test tubes [Able to provide an idea of materials and apparatus used] Iron nail, steel nail, jelly solution 8. (v) KK050 Experimental procedure [Able to state all experimental steps correctly]. Rub nails with sandpaper until clean of rust.. Put iron nail in test tube and steel nail in test tube.. Add jelly solution containing potassium hexacyanoferrate(iii) into the test tubes until the nails are completely immersed in it.. Leave the nails for three days. 5. After three days, observe the intensity of the blue colour. [Able to provide steps correctly to carry out the experiment] Steps, and [Able to provide minimum of steps correctly to carry out the experiment] Steps and Chemistry Perfect Module Form 00 Marking Scheme Set 5

6 Set 5 Marking Scheme :Manufactured Substances in Industry (vi) KK Tabulation of data [Able to construct a table correctly containing the following elements] - Columns and rows - Observation for each test tube Test tube No. Intensity of blue colour [Able to construct a tabulation of data containing the following elements] - Rows and columns present - Observation Test tubes Observation [An idea of a tabulation of data ] - Minimum of rows and columns Chemistry Perfect Module Form 00 Marking Scheme Set 5

CHAPTER 9. The Uses of Sulphuric Acid

CHAPTER 9. The Uses of Sulphuric Acid CHAPTER 9 MANUFACTURED SUBSTANCES IN INDUSTRY SULPHURIC ACID The Uses of Sulphuric Acid 175 POLLUTION of Sulphur DIOXIDE Formation of Acid Rain Burning of Sulphur Burning of Sulphur Dioxide 176 Effect