Chemistry-Changes

• Ore


  A metal compound within a rock that is mined and then purified
• Whether it is worth extracting a particular metal depends on: How easy it is to extract it from its ore, How much metal the ore contains, The changing demands for a particular metal
• Most metals in ores are chemically bonded to other elements in compounds. Many of these metals have been oxidised (have oxygen added) by oxygen in the air to form their oxides
• Extracting metals from their oxides

  The metal oxides must be reduced (have oxygen removed)
• Reactivity series

  • Potassium
  • Sodium
  • Lithium
  • Calcium
  • Magnesium
  • Carbon
  • Zinc
  • Iron
  • Lead
  • Hydrogen
  • Copper
  • Silver
  • Gold
• Reactivity of a metal

  Linked to its tendency to form positive ions
• Gold and silver do not need to be extracted. They occur native (naturally)
• Extracting metals above carbon

  Must be extracted from their ores by using electrolysis
• Extracting metals below carbon


  Can be extracted from their ores by reduction using carbon
• Reduction

  Involves the loss of oxygen
• Displacement reactions

  A more reactive metal can displace a less reactive metal from its compound
• Ionic equation


  Shows only the atoms and ions that change in a reaction
• Half equations


  Show what happens to each reactant
• Oxidation


  Loss of electrons
• Reduction

  Gain of electrons
• Redox reactions

  Reactions involving oxidation and reduction
• Reactions of acids - PART 1

  • Acids and metals
  • Neutralisation of acids
  • Soluble salts
• Acids react with some metals to produce salts and hydrogen
• Reactions between metals and acids only occur if the metal is more reactive than the hydrogen in the acid
• Nitrates

  Salts made when metals react with nitric acid
• Sulfates


  Salts made when metals react with sulfuric acid
• Chlorides

  Salts made when metals react with hydrochloric acid
• Spectator ions

  Ions that do not change in a reaction
• Neutralisation of acids

  Acids are neutralised by alkalis (eg: soluble metal hydroxides) and bases (eg: insoluble metal hydroxides and metal oxides) to produce salts and water, and by metal carbonates to produce salts, water and carbon dioxide
• Soluble salts

  Can be made from acids by reacting them with solid insoluble substances, such as metals, metal oxides, hydroxides or carbonates
• Making soluble salts from acids and alkalis

  Acid + Alkali → Salt + Water
• Making soluble salts from acids and bases

  Acid + Bases → Salt + Water
• Making soluble salts from acids and metal carbonates

  Acid + Metal carbonate → Salt + Water + Carbon dioxide
• Magnesium sulfate

  • MgSO4
• Soluble salts can be made from acids by reacting them with solid insoluble substances, such as metals, metal oxides, hydroxides or carbonates
• Making Soluble Salts

  1. Measure the required volume of acid, add the weighed solid (insoluble metal, oxide, hydroxide or carbonate) in small portions with stirring

  2. Filter the solution to remove the excess solid metal/oxide/carbonate, into an evaporating dish

  3. Hot concentrated solution is left to cool and crystallise

  4. Collect and dry the crystals with a filter paper
• Heating a solution until all the solvent has evaporated is known as heating to dryness
• When acids react with metals, a salt and water are produced
• Redox reaction

  Oxidation and reduction
• When an acid reacts with a carbonate, a salt, water and carbon dioxide are produced
• Salts produced by different acids

  • Hydrochloric acid: Chloride
  • Sulfuric acid: Sulfate
  • Nitric acid: Nitrate
• Making Soluble Salts from acids and insoluble substances

  Solid added to acid until no more reacts; excess solid filtered off
• Crystallisation

  The process of producing solid salts from salt solution
• Magnesium + sulfuric acid → magnesium sulfate + hydrogen
• Sodium hydroxide + hydrochloric acid → sodium chloride + water