Question

Nitric acid is an oxidising agent and reacts with \[\ce{PbO}\] but it does not react with \[\ce{PbO2}\]. Explain why?

Answer 1

\[\ce{PbO}\] is a basic oxide and simple acid base reaction takes place between \[\ce{PbO}\] and \[\ce{HNO3}\]. On the other hand in \[\ce{PbO2}\] lead is in + 4 oxidation state and cannot be oxidised further. Therefore no reaction takes place. Thus, \[\ce{PbO2}\] is passive, only \[\ce{PbO}\] reacts with \[\ce{HNO3}\].

\[\ce{2PbO + 4HNO3 -> 2Pb (NO3)2 + 2H2O}\] (Acid base reaction)