Take some crystals of copper sulphate (CuSO4.5H2O) in a test tube
Heat these crystals on a burner
Note the change in colour of the copper sulphate crystals during the heating. Does it show a bluish white colour? If yes, keep on heating the crystals for some more time. After some time as temperature reaches around 250 °C, the copper sulphate crystals starts appearing white.
Stop heating when it becomes complete white
Keep the test tube in open atmosphere for some time and allow it to cool. Do you find a change in the colour of copper sulphate crystals
One of the sales turns blue litmus red and the gas turns lime water milky
Sample which turned red litmus blue and lime water milky contains baking powder
Blue crystals of copper sulphate contains water of crystallization. These crystals dehydrate on heating to lose water of crystallisation at a particular temperature and also change their colour.
If the dehydrated copper sulphate solid material is allowed to cool in air, then it regains blue colour after gaining water molecules from the atmosphere.
CuSO4 • 5 H20 (bluish) → CuSO4(anhydrous, white) + 5 H2O