Chemical Reactions and Equations

Double Displacement Reaction

Chemical Reaction in which exchange of ions takes place between two compounds is called Double Displacement Reaction.

This type of reaction called Double Displacement because two displacements take place in such reactions. This is also known as Double Replacement Reaction or Metathesis Reaction.

A double displacement reaction can be represented as follows:

Example: 1:

When the solution of barium chloride is added to the solution of sodium sulphate, barium sulphate and sodium chloride are formed.

In this reaction sulphate and chloride ion are get exchanged between sodium sulphate and barium chloride and form barium sulphate and sodium chloride. In this reaction white precipitate of barium sulphate is formed.

As two replacements or displacements take place here, so this type of reaction is called Double Displacement Reaction or Double Replacement Reaction.

Example: 2:

When hydrochloric acid reacts with sodium hydroxide, it gives sodium chloride and water. This reaction takes place by double displacement of ions between reactants.

Here, chloride ion exchanges with hydroxide ion.

Example: 3:

When silver nitrate reacts with sodium chloride it gives silver chloride and sodium nitrate.

In this reaction, nitrate ion of silver nitrate exchanges chloride ion from sodium chloride and produce silver chloride and sodium nitrate.