Chemical Reactions and Equations — Question 15

A chemical reaction in which two compounds in their aqueous state react to form an insoluble substance (precipitate) as one of the products is called a precipitation reaction.

Some examples of precipitation reactions are:

1. Take a solution of silver nitrate in a test tube and add dil. hydrochloric acid. A curdy white ppt. of AgCl is formed.
   AgNO₃ (aq) + HCl (l) ⟶ AgCl (s) ↓ + HNO₃ (g)

2. When sodium sulphate reacts with barium chloride, a white ppt. of barium sulphate appears.

Na₂SO₄ (aq) + BaCl₂ (aq) ⟶ BaSO₄ (s) ↓ + 2NaCl (aq)