Question

What is the colour of ferrous sulphate crystal? How does colour change after heating?

Answer 1

Dear Student,

Ferrous sulphate is green in colour. On heating, the green crystals are converted into a dirty-yellow anhydrous solid as it loses water of crystallization. When further heated, the anhydrous material releases sulphur dioxide and sulphur trioxide leaving a reddish-brown iron oxide.

The chemical reaction that takes place is given as under:

2 FeSO₄ → Fe₂O₃ + SO₂ + SO₃

Regards