Question

Blue crystalsof CuSo4 on heating in a dry test tube become colourless .give reasons

Answer 1

This is because CuSO4 Is chemically  bonded with water to give the crystalline blu colur. On heating, the water evaporated, breaking the bond of CuSO4 and Water, thus giving a white precipitate. The reaction is like this-

                        Heating

CuSO4.H2O-------------> CuSO4 (Water evaporates)