Question

Pieces of blue vitriol were heated in a test tube. On cooling, water was added to it.

Write down the changes that will be seen in each instance and explain the reason behind it.

(h)  Pieces of blue vitriol were heated in a test tube. On cooling, water was added to it.

Answer 1

When pieces of blue vitriol are heated in a test tube, then crystal structure of blue vitriol broke down to form a colourless powder and water come out.

This water is called water of crystallization.

When water is added to the same test tube, then white powder turned into blue colour again.

This is due to reversible reaction take place from anhydrous salt to hydrous salt and vice-versa.

All above changes are physical changes.