Question

When a green salt is heated strongly it's colour finally changes to brown and odour of sulphur is given out.

i) Name the iron salt.
ii) Name the type of reaction that takes place during the heating of iron salt.
iii) Write the chemical equation for the reaction involved.

Answer 1

The iron salt that turns from green to brown upon heating and releases a sulfur odor is iron(II) sulfate. The reaction is a thermal decomposition, resulting in iron(III) oxide, sulfur dioxide, and sulfur trioxide, and is typically an exothermic process.

Step-by-step explanation:

When a green salt containing iron is heated strongly and changes color to brown with the odor of sulfur being emitted, the salt is likely iron(II) sulfate, commonly known as green vitriol. Upon heating, the reaction that takes place is a thermal decomposition, where the compound breaks down upon heating to form iron(III) oxide, sulfur dioxide, and sulfur trioxide.

The balanced chemical equation for this reaction is:

2 FeSO4 → Fe2O3 + SO2 + SO3

This chemical reaction is exothermic, meaning it releases heat. The resulting iron sulfide has a dark color and is a new product with different properties from the reactants, indicating that a synthesis reaction has taken place.