When dilute sulphuric acid is added to pieces of iron sulphide, hydrogen sulphide gas is produced and soluble ferrous sulphate is formed. The type of chemical reaction involved is
Dilute sulphuric acid: dil. H2SO4
Iron sulphide: FeS
Hydrogen sulphide: H2S
Ferrous sulphate: FeSO4
The reaction involved can be written as:
FeS + H2SO4→ FeSO4 + H2S
We can see that there is the exchange of SO42- and S2- ions in the reactants. Thus it is a double displacement reaction.