Question

Crystals of a substance changed their color on heating in a closed test tube but regained it after some time when they were allowed to cool down. Name the substance and write it’s formula and explain the phenomenon involved.

Answer 1

Answer: Hydrated copper sulphate

are the crystals of a substance that changes its colour on heating in a closed test tube but regained its colour when it is cool down after some time.

Formula of hydrated copper sulphate is CuSO4.5H2O.

The phenomenon is the presence of water molecules in the crystals of copper sulphate. When it is heated the water molecule is evaporated and colour is change and when it is allowed to cool down then regained its colour.