I'm having some more half reaction difficulty?

Question

NH3 + PbO = N2 + Pb + H20

I don't understand what to seperate into the reduction and oxidation equations and then how to balance it. I can do single elements added together in a synthesis but not these.

THanks in advanced

Answer 1

One half-reaction is H2O + PbO +2e- ===> Pb + 2OH-

The other is 2NH3 +6OH- ===> N2 + 6e- + 6H2O

Electrons lost must equal electrons gained. So you multiply the first equation by 3 and add them together:

3H2O + 6e- + 3PbO ===> 3Pb + 6OH-
2NH3 +6OH- ===> N2 + 6e- + 6H2O

2NH3 + 3PbO ===> N2 + 3Pb + 3H2O