Write the balanced equation with state symbols for the following chemical reactions.
(i) Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.
(ii) Sodium hydroxide solution (in water) with hydrochloric acid solution (in water) to produce sodium chloride solution and water.

Explanation

When a solution of sodium sulphate is added to a solution of barium chloride a white precipitate of barium sulphate will be formed immediately. This precipitate is insoluble in dil-Hydrochloric acid and also insoluble in water. This type of reaction is called precipitation reaction as the `BaSO_4` precipitate thus formed is of white colour.
`Na_2 SO_4 (aq) + BaCl_2 (aq) to BaSO_4(s) + 2NaCl(aq)`
Since, barium sulphate is insoluble in water. So it will precipitate as a solid, whereas the sodium chloride will remain in solution.