Chemical Changes

• pH scale


  Goes from 0 to 14
• pH range


  • 1-6 acidic
  • 7 neutral
  • 8-14 alkaline
• Acid and base neutralisation

  Acid + base -> salt + water
• When an acid neutralises a base, the products are neutral
• Reactions of acids


  1. Acid + metal oxide -> salt + water

  2. Acid + metal hydroxide -> salt + water
• Neutralisation reactions


  Acid + metal oxide -> salt + water

  Acid + metal hydroxide -> salt + water
• Acid + metal carbonate


  Salt + water + carbon dioxide
• Reactivity series

  Order of reactivity of metals

  Determined by how easily they lose electrons - forming positive ions
• Acid + metal--->


  Salt + hydrogen
• Metal + water--->

  Metal hydroxide + hydrogen
• Oxidation


  Addition of oxygen and loss of electrons
• Reduction


  Removal of oxygen and gain of electrons
• OIL RIG


  Oxidation Is Loss, Reduction Is Gain
• Reduction and oxidation happen at the same time, hence redox
• In displacement reactions, the metal iron always gains electrons and is reduced. The metal atom always loses electrons and is oxidised.