Question

PbO2(s) + Pb(s) + H2SO4(aq)  PbSO4(s) + H2O(l)

Can anyone help me identify what the redox reactions are for this equation? I don't understand how to do it when there are more than 2 chemicals.

Answer 1

The way you do it is to write the oxidation state above each individual element/ion, then determine which ones change oxidation state. The loss of electrons is oxidation and the gain of electrons is reduction.
Pb in PbO2 is +4 and in PbSO4 is +2. Pb on the left is zero (in the elemental state all elements are zero). So PbO2 goes to PbSO4 and Pb goes to PbSO4.
+4 to +2 is gain of electrons so that is reduction. 0 to +2 is loss of electrons which is oxidation.