PbO and PbO2 react with HCl according to the following chemical equations:
2PbO + 4HCl → 2PbCl2 + 2H2O
PbO2 + 4HCl → PbCl2 + Cl2 + 2H2O
Why do these compounds differ in their reactivity?
In reaction (i), none of the atoms changes. Therefore, it is not a redox reaction. It is an acid-base reaction because PbO is a basic oxide which reacts with HCl acid.
The reaction (ii) is a redox reaction in which PbO2 gets reduced and acts as an oxidizing agent.