Barium sulphate is washed with water containing a little amount of dilute `H_(2)SO_(4)` in gravimetric analysis. Justify.

Explanation

The addition of `H_(2)SO_(4)` to the solution containing the white precipitate of `BaSO_(4)` will suppress the dissociation of the salf in water by furnishing `SO_(4)^(2-)` ions to the solution which act as the common ions.
`BaSO_(4)(s) overset((aq))(hArr) Ba^(2+) (aq) + SO_(4)^(2-) (aq)`
`H_(2)SO_(4) overset((aq))(to) 2H^(+) (aq) +SO_(4)^(2-) (aq)`
This will check the dissociation of `BaSO_(4)` and thus help in its complets precipitation.