Why do the following reactions proceed differently? Pb3O4+ 8HCl----->3PbCl2+ Cl2+ 4H2O and Pb3O4+ 4HNO3---->2Pb (NO3)2+ PbO2+ 2H2O
Why do the following reactions proceed differently?
Pb3O4+ 8HCl----->3PbCl2+ Cl2+ 4H2O and
Pb3O4+ 4HNO3---->2Pb (NO3)2+ PbO2+ 2H2O
1 Answers
Pb3O4 is actually a stoichiometric mixture of 2 mol of PbO and 1 mol of PbO2. In PbO2, lead is present in +4 oxidation state , whereas the stable oxidation state of lead in PbO is +2. PbO2 thus can act as an oxidant (oxidizing agent) and, therefore, can oxidiseCl– ion
ofHCl into chlorine ,.AsPbO is a basic oxide. So, the reaction
Pb3O4+ 8HCl ------>3PbCl2+ Cl2+ 4H2O
can be splitted into two reactions namely:
2PbO + 4HCl------> 2PbCl2+ 2H2O
PbO2+ 4HCl--> PbCl2+ Cl2+2H2O
Since HNO3 itself is an oxidizing agent therefore, it is unlikely that the reaction mayoccur between PbO2 and HNO3. However, the acid-base reaction occurs between PbO and HNO3 as:
2PbO + 4HNO3--------------> 2Pb (NO3)2+ 2H2O
It is the passive nature of PbO2 against HNO3 that makes the reaction different from the one that follows with HCl.