- The electrochemical series is a series of arrangement of metals according to the order of the tendency of the metal to lose electrons to form positive ions.
- Elements which placed higher in the electrochemical series
- are more electropositive
- act as strong reducing agent
- can be oxidised easily
- The metal ions are weak oxidising agents because they do not have a tendency to gain electrons.
- In a reaction of displacement of metal, a metal which is placed on the top of the electrochemical series (more electropositive) can displace other metals that lie below it ( less electropositive) from its salt solution.
- there is a transfer of electrons from a more electropositive metal to the ions of a metal which is less electropositive.
- The more electropositive metal acts as a reducing agent. The metal experiences oxidation and is oxidised to a metal ion.
- The metal ion which is less electropositive acts as an oxidising agent. This ion experiences reduction and is reduced to a metal.
The reaction between magnesium and copper(II) sulphate solution
The blue colour of copper(II) sulphate solution turn colourless.
- Magnesium is more electropositive than copper.
- In the reaction, magnesium displaced copper(II) ions from the solution.
- Magnesium is oxidised by releasing 2 electrons.
- Copper(II) ion is reduced by receiving 2 electrons from magnesium.
Oxidising agent: Copper(II) ion
Reducing agent: Magnesium