C15

• Rusting is the corrosion of iron
• Rust is a form of iron (III) oxide called hydrate iron oxide
• Both air and water must be present for rusting to occur
• Bronze is an alloy copper+tin
• Brass is an alloy of 60% copper and 34% zinc
• alloys of iron are called steels
• cast iron is iron from a blast furnace and is alloy of 96% iron, carbon, phosphorus, silicon, sulfur impurities
• stainless steel is alloy of chronium and nickel
• bronze is used to make statues and ship propellers due to its toughness and resistance to corrosion
• Brass is used to make musical instruments, door fittings and taps
• Aluminium is strong but lightweight and is used to build aircrafts
• pure gold is 24k
• 75% gold is 18k
• gold can be made harder by alloying it with other elementsd
• stainless steels are used for cutlery
• Composites contain a matrix/binder of 1 material surrounding and binding togehter fibres or fragments of the other material - a process called reinforcement
• Fibreglass is a composite of glass with polymers as the binding material.
• fibreglass forms tough, flexble waterproof material with low density
• concrete is very hard strong composite
• Thermosoftening polymers have weak intermolecular forces between the chains so when heated they break apart. when they cool down, the intermolecular forces bring the chains back together
• Thermosetting polymers have strong covalent bonds that form cross-links between chains when cooling down
• High density polyethene (HDPE) is made from ethene using a catalyst at 50ºC & a slight raised pressure
• HDPE has a higher softening temp & is strong than LDPE due to its high force of attraction because chains are closer together
• HABER PROCESS EQUATION: N2(g) + 3H2(g) ⇌ 2NH3(g)
• IN HABER PROCESS, increasing pressure will increase yield of ammonia
• IN HABER PROCESS, a pressure of 200 atmospheres is used
• Ethene forms LDPE when using very high pressures and a trace of oxygen
• In lab, ammonia solution is reacted with nitric acid to form ammonia
• In haber process, the forward reaction is exothermic
• in haber process, lowering temp increases yield of ammonia but the reaction rate decreases
• in haber compromise temperature is 450ºC
• in haber process, an iron catalyst is used, which speeds up both reactions so doesn't affect yield of ammonia but decreases reaction time
• Nitrogen is obtained from air
• Hydrogen is obtained from natural gas
• NPK fertilizers contain nitrogen, phosphorus and potassium
• Nitrogen promotes healthy leaves
• Potassium promotes growth, healthy fruit and flowers
• Phosphorus promotes healthy roots
• The source of nitrogen in fertilisers is ammonia produced in Haber process. Ammonia is reacted with acids to make fertilizers in ammonium nitrate
• Phosphate rock treated with nitric acid to produce phosphoric acid and calcium nitrate. Phosphoric acid is the neutralized with ammonia to produce ammonium phosphate.