Question

Describe an activity to illustrate a decomposition reaction by heating.

Answer 1

1. Take about 2 grams of ferrous sulphate crystals in a dry boiling tube. The ferrous sulphate crystals are green in colour.
2. Heat the boiling tube over a burner (by keeping the mouth of the boiling tube away from yourself and your neighbour working in the laboratory) (see Figure).
3. The green colour of ferrous sulphate crystals first changes to white, then a brown solid forms (ferric oxide).
4. Gas with the smell of burning sulphur comes out of the boiling tube (We should smell the gas by gently turning it towards our nose with a blow of our hand, not by bringing the mouth of the boiling tube under our nose).

Decomposition reaction of ferrous sulphate