Question

Why wash precipitate with distilled water?

Answer 1

the precipitate is a solid. it might have traces of solution around it. distilled water is used to wash the precipitate for the following reasons: 
(i) it washes away the traces of solution around the precipitate 
(ii) distilled water is not an impurity, so it does not spoil the precipitate 
(iii) distilled water is relatively fluid and volatile, making it easy to dry by using filter paper or by evaporation

Answer 2

distlled water is related fluid and it's have no impurities and it's a homogeneous mixture. hopes it's help u. ......!