Metals

Metals

1. Metal from Rocks

   • Ores = enough metal to make economically worthwhile
     • usually oxides - aluminium ore = bauxite
     • technology improves = extract more = more worth it than past
   • Reduction with Carbon
     • higher than carbon = electrolysis
     • below carbon = reduction - carbon
   • Electrolysis = Splitting up with Electricity
     • copper reduced = impure - not useful for electrical wiring
     • liquid - electrolyte - conduct electricity
       • free ions - conduct
         • electrons pulled off copper atoms - anode(+ve) = Cu²⁺ ions
           • C²⁺ ions gain electrons - cathode(-ve) = copper atoms
             • impurities - anode - sludge pure copper atoms - cathode
             • cathode = thin piece of pure copper
             • anode = impure copper - dissolves
   • Extract copper - Displacement Reaction
     • reactive metal in dissolved compound solution = reactive metal replace less reactive metal
       • bonds more strongly & pushes out less reactive metal
         • scrap iron "kicks out" copper from iron sulfate solution
           • copper sulfate + iron → iron sulfate + copper
   • Copper-rich Ores = Short Supply
     • Bioleaching = bacteria - get energy from copper sulfate bond - seperates copper - leachate contains copper - filtered
     • Phytomining = grow plants in soil with copper - can't use/rid copper = builds up in leaves Harvested, dried & burned - copper collected from ash

2. Impacts of Extracting Metals

   • Recycling Metals = Important
     • energy = fossil fuels
       • running out - conserve - acid rain, global dimming, climate change
         • recycling uses small fraction of energy needed to mine/extract
           • saves money
             • less landfill rubbish - pollutes

3. Properties of Metals

   • Metals = strong & bendy & Conductors
     • bridges & car bodies
     • saucepans
     • electrical wires
   • Different Properties
     • copper - good conductor - hard, strong, can be bent - doesn't react with water
     • aluminium - corrosion-resistant & low density
     • titanium - low density metal - very strong - corrosion-resistant
     • plumbing - bent for pipes - doesn't react with water = copper
     • aeroplane - strong & bent into shape - light = aluminum
     • replacement hips - no corroding - light = titanium

4. Using Limestone

   • Calcium Carbonate
     • Heat = thermal decomposition
       • calcium carbonate → calcium oxide + carbon dioxide CaCO₃ → CaO + CO₂
       • magnesium, copper, zinc & sodium carbonates = decompose - same
     • reacts with acid = calcium salt, CO₂ & H₂O
       • calcium carbonate + sulfuric acid → calcium sulfate + carbon dioxide + water CaCO₃ + H₂SO₄ → CaSO₄ + CO₂ + H₂O
   • calcium oxide + water → calcium hydroxide
     • alkali - neutralise acidic soil - quickly = advantage
     • test for CO₂ = bubble gas through limewater = cloudy if there's CO₂ - calcium carbonate formed
       • calcium hydroxide + carbon dioxide → calcium carbonate + water Ca(OH)₂ + CO₂ → CaCO₃ + H₂O
   • heated in kiln with powdered clay = cement cement + sand & water = mortar - stick bricks cement + sand & aggregate = concrete
   • Quarrying = Scars Landscape
     • huge ugly holes
     • noise and dust
     • destroys habitats
     • transported in lorries
   • Pollution
     • cement factories = dust = breathing problems
     • energy - cement & quicklime - fossil fuels
   • houses, roads & dyes, paints, medicines
   • neutralise acidic soil & lakes - acid rain
   • neutralise sulfur dioxide
   • jobs = local economy money = local improvements
   • landscaping & restoration after quarrying
   • widely available & cheap
   • hard-wearing & attractive
   • concrete - moulds - quick & cheap
     • unattractive
   • doesn't rot - insects can't gnaw & fire-resistant
   • concrete - doesn't corrode
     • low tensile strength unless reinforced with steel

5. Alloys

   • Pure Iron = Too Bendy
     • 96% iron - 4% impurities = carbon
       • cast iron = ornamental railings - brittle
     • regular arrangement - slide over each other - soft & easily shaped = too bendy
   • Steel = Alloy
   • different elements = different size atoms - smaller atoms disrupt layers - alloys = harder
     • BRONZE = COPPER + TIN - harder
     • CUPRONICKEL = COPPER + NICKEL - hard & corrosion resistant
     • GOLD ALLOYS = JEWELLERY - harder
     • ALUMINIUM ALLOYS = AIRCRAFT - low density but alloyed = stronger

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