Question

On heating green coloured crystals, a gas with a characteristic odour of burning sulphur evolves and the colour of the crystal changes
(i) Identity the green crystals
(ii) Name the gas evolved with its chemical formula
(iii) Write the chemical equations involved. Name the type of chemical reaction taking place​

Answer 1

Answer:

(i) ferrous sulphate hepta hydrate.

(ii) the gases evolved are SO2 and SO3.

(iii) FeSO4.7H2O   →   Fe2O3(s)  +  SO2↑(g)  +  SO3↑(g)

  ferrous sulphate       ferric          sulphur        sulphur

    hepta hydrate        oxide         dioxide         trioxide

this is decomposition reaction.

Explanation:

Answer 2

(i). The green colored crystals are ferrous sulphate heptahydrate (  FeSO$_{4}$.7H$_{2}$O ) .

(ii). The gases evolved are sulphur dioxide and sulphur trioxide . The chemical formula of sulphur dioxide is SO$_{2}$ and the chemical formula of sulphur trioxide is SO$_{3}$  .

(iii). The balanced chemical equations are as follows -

FeSO$_{4}$.7H$_{2}$O  →  FeSO$_{4}$ + 7H$_{2}$O  

2 FeSO$_{4}$  →  Fe$_{2}$O$_{3}$(s)  +  SO$_{2}$ ↑ (g)  +  SO$_{3}$ ↑ (g)

The type of chemical reaction taking place​ is a decomposition reaction .