Question

On heating green coloured crystals, a gas with a characteristics odour of burning sulphur evolves and the colour of the crystals changes.
(a) Name the gas evolved with its chemical formula.
(b) Identify the green crystals.
(c) Name the type of chemical reaction taking place.

Answer 1

a) Sulphur dioxide, SO₂ and sulphur trioxide, SO₃ are evolved giving smell of burning sulphur.
b) Green crystals are of Ferrous sulphate.
c) It is a decomposition reaction.
2 FeSO₄ → Fe₂O₃ + SO₂ + SO₃