chem 2e edexcel igcse

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dawandw iwjdoijw

Cards (8)

  • metals are found in the crust of the earth. usually they are extracted from ores, but unreactive metals are usually found as the uncombined element.
  • metals are often extracted through reduction of carbon, unless theyre more reactive than carbon, in which case they are extracted through electrolysis- though, this is expensive because it needs a lot of energy. so if carbon extraction is possible, it is usually done instead
  • extraction of iron is done by carbon reduction. it is usually carried out at high temperatures in a blast furnace.
  • aluminium is extracted through electrolysis. the electrolyte is made up of aluminium oxide and cryolite, which is used to reduce the melting point so less energy has to be used.
  • alternate methods of metal extraction include:
    • phytoextraction, which is burning plants to obtain the metal compounds they absorb through their roots.
    • bacterial extraction, which is producing solutions called leachates which contain bacteria which absorb metals
  • the uses of metals:
    • aluminium is low density and corrosion resistant. its uses include aircraft, saucepans and cooking foil.
    • copper is easily bent, doesnt react with water and conducts electricity. its uses include electrical wire and plumbing.
    • iron is often converted to steel or soft iron because it is too soft or brittle for most uses.
  • the uses of metals:
    • low carbon steel: its made up of 0.25% carbon and is malleable, often used for car body panels.
    • high carbon steel: its made up of 2.5% carbon and is hard, often used for cutting tools.
    • stainless steel: its made up of chromium and nickel and is resistant to corrosion, often used for cutlery and sinks.
  • an alloy is a mixture of a metal and other elements, usually other metals or carbon. alloys are used in most everyday metals because pure metal is often too soft. this is because the layers in the metal are made of ions that are the same size and in a regular arrangement, so they slide over eachother easily. in alloys, differently sized ions prevent this.