- Take about 2 g ferrous sulphate crystals in a dry boiling tube.
- Note the colour of the ferrous sulphate crystals. (Colour is green).
- Heat the boiling tube over the flame of a burner or spirit lamp as shown in Fig. 1.4.
- Observe the colour of the crystals after heating.
Green colour of ferrous sulphate is changed with characteristic odour of burning sulphur.
When heated, ferrous sulphate (FeSO4. 7H2O) lose water. It then decomposes to ferric oxide (Fe2O3), sulphur dioxide (SO2) and sulphur trioxide (SO3).