Series of Reactivity of Metals

  1. When a metal reacts with oxygen to form a metal oxide, a redox reaction occurs.
    Metal + Oxygen → Metal oxide
  2. In this reaction,
    1. Metal is oxidised to metal ions. The oxidation number of the metal increases.
    2. Oxygen is reduced to the oxide ion. The oxidation number of oxygen decreases from 0 to -2.
    3. Metal acts as a reducing agent while oxygen acts as an oxidising agent.
  3. Different metals burn in oxygen with different rate depending on their differing activeness.
  4. The more reactive metal towards oxygen, the brighter and faster the combustion of the metal.
  5. The arrangement of the metal according to the tendency of reaction with oxygen to form the metal oxide is known as the reactivity series of metals.
  6. Figure above shows the experiment is conduct to build the reactivity series of metal. Table below shows the result of the experiment.
MagnesiumCombust quickly with a bright white shiny flame. A white powder is formed.
ZincA bright flame spread slowly. The powder produced is yellow when hot, and white when it is cold.
IronEmbers spread slowly. A reddish brown powder is formed.
LeadRed hot embers slowly. The powder produced is brown when hot, and yellow when it is cold.
CopperEmbers burn at a very slow rate. A black powder is formed.
    1. Oxygen that is used in combustion of other metals is provides by heating solid potassium manganate(VII), also can be obtained from
      1. heating the mixture potassium chlorate (V) and manganese (IV) oxide (catalyst)
        2KClO3 (s) → 2KCl (s) + 3O2(g)
      2. heating potassium nitrate
2KNO3 (s) → 2KNO2 (s) + O2(g)