SO3 + H20 H2SO4. Sulphuric Acid, H2SO4 Uses i) Produce fertilizer (Ammonium Sulphate)

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1 Page 1 of 12 Sulphuric Acid, H2SO4 Uses i) Produce fertilizer (Ammonium Sulphate) Manufacturing (Contact Process) 2NH 3 + H 2 SO 4 (NH 4 ) 2 SO 4 ii) Electrolyte in car batteries iii) Manufacture paint pigment iv) Manufacture detergents v) Manufacture artificial fibres Stage 1 : Burn Sulphur in air S + O 2 SO 2 (Sulphur Dioxide) Stage 2 : React with excess O2 SO 2 + O 2 SO 3 (Sulphur Trioxide) Catalyst : Vanadium Oxide, V2O5 Temperature : 450 o c Stage 3 : Dissolve in concentrated H2SO4 SO 3 + H 2 SO 4 H 2 S 2 O 7 (Oleum) Stage 4 : Dilute with water H 2 S 2 O 7 + H 2 O 2H 2 SO 4 (Sulphuric Acid) Sulphur Trioxide cannot dissolve in water directly because the reaction is very vigorous and releases a lot of heat Production of Harmful Substances Fossil fuels like petroleum and manufactured products of sulphuric acid, H2SO4, contain sulphur Formation of Sulphurous Acid Formation of Sulphuric Acid - Burning these products oxidises Sulphur to produce Sulphur Dioxide, SO2 S + O2 SO2 - Sulphur Dioxide then dissolves in rainwater to form sulphurous acid, H2S03 causing acid rain Pollution (SO2) SO2 + H20 H2SO3 Causes : Acid Rain Effects : - Corrodes building and metal structures - Makes soil acidic & not suitable for growth of plants - Makes water acidic & not suitable for aquatic life - Sulphur Trioxide will also form when Sulphur Dioxide reacts with oxygen 2SO2 + O2 2SO3 - When Sulphur Dioxide dissolves in water, sulphuric acid is formed causing acid rain SO3 + H20 H2SO4

2 Page 2 of 12 Ammonia, NH3 Uses i) Produce fertilizer (Ammonium Sulphate) 2NH 3 + H 2 SO 4 (NH 4 ) 2 SO 4 ii) Make nitric acid and explosives iii) Manufacture synthetic fibre Manufacturing (Haber Process) - Nitrogen gas (fractional distillation of air) and Hydrogen gas (Methane Has, CH4) are mixed in the ratio of 1 : 3 N 2 + 3H 2 2NH 3 Temperature : 450 o c Pressure : 200 atm Catalyst : Iron, Fe - The condenser then cools the mixture (- 50 o c) forming ammonia solution, NH3 - The unreacted Nitrogen and Hydrogen is flowed back to the catalyst chamber Additional Information - The Haber Process is named after a German chemist, Fritz Haber ( ) who successfully synthesized ammonia from nitrogen and hydrogen - Iron fillings are used as a catalyst to speed up the chemical reaction - Molybdenum, Mo, or Potassium Hydroxide, KOH, can be used as a promoter to enable the catalyst to work more effectively - Hydrogen is obtained between the reaction of methane and steam CH4 + H20 CO + 3H2

3 Page 3 of 12 Alkaline Properties Colourless & pungent smell (sharp / strong) Reacts with concentrated HCl to form white fumes (test for ammonia gas) Very Soluble in Water The red litmus paper changes to blue Preparation of Ammonium Fertilizers Water level fills the test tube 1. Ammonium Fertilizers are nitrogenous fertilizers that can provide nitrogen to plants 2. Ammonia, NH3, dissolves in water to form ammonia solution, NH3 (aq) 3. Can be acquired through neutralization (excess goes back to catalyst chamber) Ammonia solution + Prosphoric Acid Ammonium Phosphate 3NH3 + H3PO4 (NH4)3PO4 Ammonia solution + Nitric Acid Ammonium Nitrate NH3 + HNO3 NH4NO3 Ammonia solution + Sulphuric Acid Ammonium Sulphate 2NH3 + H2SO4 (NH4)2SO4

4 Page 4 of 12 Alloys Characteristics Pure Metals Alloys Atomic Arrangement Arrangement of atoms - Same size and type of atoms - Orderly arranged - Empty space between atoms When force is applied Properties - Layer of atoms slide over each other easily - Weak and soft - Ductile (can be stretched into a wire) - Malleable (can be knocked or pressed into desired shapes) - Mixture of metal and other elements - Different size of atoms - Not orderly arranged - Layer of atoms cannot slide over each other - Harder and stronger - More resistant to corrosion / rusting - More attractive appearance Examples Alloy Composition Properties Uses Bronze Copper (90%), Tin (10%) Strong, hard and withstands corrosion Make statue, medals, bells Brass Copper (70%), Zinc (30%) Strong and shiny Musical instuments, ornaments, keys Pewter Antimony (1%), Tin (97%), Copper (2%) Smooth, shiny surface and withstands corrosion Ornamental Items (Picture frames and trophies) Copper Nickel Copper (75%), Nickel (25%) Strong and shiny silver colour To make coins Duralumin Aluminium (93%), Copper (3%), Magnesium (3%), Manganese (1%) Strong, light and withstands corrosion To make body of airplanes and racing bicycles Steel Iron (99%), Carbon (1%) Strong, hard and withstands corrosion Bridges, Vehicles, Skeleton and Train Tracks Stainless Steel Iron (74%), Chromium (18%), Carbon (8%) Strong, shiny and withstands corrosion Kitchen Utensils (spoons, forks, knives)

5 Page 5 of 12 Hardness of Pure Metal & Alloy 1. Set up an experiment as shown in the diagram using a constant height of the weight 2. Release the weight so that it falls on the metal ball to form a dent 3. Repeat the experiment three times to obtain an average diameter of dent 4. Repeat steps 1-3 with a bronze block (alloy) 5. Measure diameter of dent produced on the copper block & bronze block and compare 6. Diameter of dent produced on the copper block is bigger than the bronze block 7. Conclusion : bronze is harder Corrosion Rates of Pure Metal and Alloy 1. Use hot agar solution for both test tubes and add a little potassium hexacyanoferrate to test the presence of Fe 2+ ions in the solutions 2. Fill the test tubes with 2 different nails (one of pure metal and one alloy) 3. The test tube containing iron nails (pure metal) will have blue spots formed because there is a presence of Fe 2+ ions in the solution 4. The dark blue spots formed on the test tube containing iron nails shows that iron corrodes faster than steel 5. Conclusion : Alloys are more resistant to corrosion

6 Page 6 of 12 Polymers - Long chains of molecules made up from many small molecules (monomers) combined through a process called polymerization - There are two types of polymers (natural and synthetic) Natural Polymers Polymers that occur naturally and normally made by living organisms Natural Polymer Monomer (small molecules) Rubber Isoprene Cellulose Glucose Starch Glucose Protein Amino Acid Fat Fatty Acids & Glycerol Nucleic Acid Nucleotides

7 Page 7 of 12 Synthetic Polymers (artificial) Man-made polymers produced from chemical compounds through polymerization (either addition or condensation) Addition Polymerization Unsaturated polymers that contain double bonds between two carbon atoms

8 Page 8 of 12 Addition Polymerization

9 Page 9 of 12 Condensation Polymerization Small molecules (H 20 & NH 3) are released during condensation polymerization Monomer Adipic Acid + Hexanediamine 1,4-dicarboxylbenzene + ethane-1,2-diol Polymer Nylon Terylene Uses of Synthetic Polymers Polymer Monomer Uses Polyethene Ethene Buckets, Plastic bags, raincoats, films, bowls, rubbish bins Polyvinyl Chloride (PVC) Chloroethene Water pipes, electric cables, mats, vinyl records, clothes hangers Polypropene Propene Ropes, bottles, chairs, drink cans, carpets Perspex Car windscreens, airplane window panes, spectacle lenses (optical instruments) Nylon Ropes, curtains, stockings, clothes Polystrene Styrene Packaging boxes, buttons, notice boards Terylene Textile items (clothes, cloths) Natural Compounds that have been Replaced by Synthetic Polymers Compounds Advantages Cotton and Silk Stronger, more durable, withstands dirt, does not wrinkle easily Paper Waterproof, does not wrinkle or tear easily Timber Does not rot easily Metal Lighter, does not corrode easily, more easily forged and coloured Glass and Ceramics Does not break easily Marble (rock) Cheaper

10 Page 10 of 12 Disadvantages of Synthetic Polymers Not biodegradable (not decomposed by microorganisms) and careless disposal causes environmental pollution Burning of Synthetic Polymers - Releases pollutants that endanger health - Examples : smoke, smelly, poisonous and corrosive gases (sulphur dioxide, pollutants that cause acid rain and greenhouse effect) Additional Information Careless disposal of Synthetic Polymers - Spoils the beauty of the environment - Causes flash floods during heavy rainfall - Endangers marine life that accidentally eats polymers such as plastic as its food Best way to manage used items made from synthetic polymers is to recycle them and using biodegradable plastic bags Glass - Made from sand with silica & silicon dioxide being the main components - Most common characteristics : o o o o Hard and brittle Chemically inert (inactive) Transparent and not permeable to gas and liquid (fluid) Does not conduct electricity and acts as a heat insulator Type of Glass Method of Production Composition Properties Fused Glass Soda-lime Glass Borosilicate Glass Lead Crystal Glass Silica, SiO 2, is heated until melted at 1700 o c and cooled rapidly Molten Silica, SiO 2, is mixed with Na 2CO 3 and CaCO 3 at 1500 o c and cooled Molten Silica, SiO 2, is mixed with Boron Oxide, B 2O 3 Molten SiO 2, is mixed with PbO and Na 2O SiO 2 - High melting point and not easy to change its shape Na 2SiO 3 and - Does not easily expand or shrink with changes of temperature - Transparent to ultraviolet rays CaSiO 3 substance - Low melting point & cannot withstand heat and chemical SiO 2 and - Easily shaped and broken - Transparent B 2O 3 substances - High melting point & can withstand heat and chemical SiO 2, PbO, Na 2O - Transparent to light and infrared ray but not to ultraviolet rays - Expands and shrinks very little and only when temperature changes - High refractive index and density - Shiny and very transparent

11 Page 11 of 12 Type of Glass Fused Glass Soda-lime Glass Borosilicate Glass Lead Crystal Glass Uses Lenses, spectacles, laboratory glassware, untraviolet column Bottles, glass containers, mirrors, electrical bulbs, glass for windows Bowls, plates, saucers, pots, cookware, laboratory glassware (beakers, test tubes, flasks) Lenses, prisms, glasses, ornamental items (crystals) Fused Glass Soda-lime Glass Borosilicate Glass Lead Crystal Glass Ceramics - Made from clay that has been heated at a very high temperature with its main component being silicate - Cannot be recycled because they are extremely heat resistant Properties of Ceramics - Brittle and extremely hard with a high melting point - Withstands compression but cracks when temperature changes drastically - Chemically inert (withstand corrosion) & good insulators of heat and electricity Uses of Ceramics - Manufacturing computer microchips - Used in the manufacturing of car engines, spacecraft, - Make dentures (enamel) superconductors, and nuclear reactors - Make porcelain, vase and ornamental items - Making of construction materials (bricks, cement, tiles, - Make plates, bowls and pots underground piping, roof tiles) Computer Microchips Dentures (enamel) Vase Bowls

12 Page 12 of 12 Composite Materials - Produced from the combination of two or more different compounds (alloys, metals, glass, polymers, ceramics) - Characteristics of produced material are much more superior than those original components Reinforced Concrete - Mixture of cement, gravel, sand, water, iron/steel to produce nets, rods, or bars - Strong, high tensile strength and cheap - Construction material for buildings, bridges, highways, and dams Fibre Glass - Made from SiO 2, Na 2CO 3, CaCO 3 - Good insulator of heat and electricity - Used to make protective apparel for astronauts and firefighters Photochromic glass - Produced from molten silica mixed with little silver chloride, AgCl - Dark in colour when exposed to bright light (ultraviolet ray) and bright when in dark - Used to make optical lenses and glass windows (windshields) of certain vehicles Plastic Strengthened with glass Fibres - Made of plastic and glass fibres Superconductor - Mixture of niobium and germanium - No electrical resistance - Can function only under extremely low temperatures - Used in transportation, telecommunication, astronomy industries and medical fields Fibre Optics - Made from glass, copper, and aluminum - Enables information to be transmitted at the speed of light - Field of communications : make electrical cables - Field of medicine : observe internal organs without performing surgery Ceramic Glass - Produced by exposing glass that contains certain amount of metals to ultraviolet rays and heating it at high temperatures - Withstand heat & used to make cooking materials and rocket heads - Composite plastics that are very strong, light, easily shaped, and can withstand corrosion - Used to make helmets, body of cars and aeroplanes, rods and other parts of aeroplanes - Fibre Optics : o o Additional Information Thickness of thread is less than 1/20 of a strand of human hair but strong, non-flammable, stretched and corrosive Can transport up to times more information than copper wires (speed of light) - Superconductors can be pushed by a magnetic force field enabling the construction of a floating train like the Yamanashi MLX01 Maglev which can move at very high speed