What is a redox reaction? Identify the substance oxidized and the substance reduced in the following reactions.
a. Pb3O4 + 8HCl → 3PbCl2 + Cl2 + 4H2O
b. CuO + H2→ Cu + H2O
The word redox is a combination of two words reduction and oxidation. So a redox reaction is the type of reaction in which reduction as well as oxidation of elements takes place simultaneously.
For the First reaction,
Pb3O4 + 8HCl → 3PbCl2 + Cl2 + 4H2O
In this reaction lead is losing its oxide state to form lead chloride. Hence lead undergoing reduction reaction.
On the other hand chlorine from hydrochloric acid is oxidized as it separated from hydrogen to give off chlorine gas.
For the second reaction,
CuO + H2→ Cu + H2O
In the above copper is getting reduced from its oxidized state to its free elemental state.
Hydrogen is getting oxidized from its free state to water molecule.