Question

What do you mean by a precipitation reaction? Explain by giving examples.

Answer 1

A reaction in which an insoluble solid (called precipitate) is formed is called a precipitation reaction. 

For example:
Na₂CO_3(aq)           +           CaCl_2(aq)                      \(→\)   CaCO_3(s)              +              2NaCl_(aq)
(Sodium carbonate)         (Calcium chloride)            (Calcium carbonate )            (Sodium chloride)
In this reaction, calcium carbonate is obtained as a precipitate. Hence, it is a precipitation reaction.

 Another example of precipitation reaction is: 
Na₂SO_4(aq)             +       BaCl_2(aq)              \( →\)        BaSO_4(s)                  +         2NaCl_(aq)
(Sodium sulphate)         (Barium chloride)            (Barium sulphate)           (Sodium Chloride)
In this reaction, barium sulphate is obtained as a precipitate.