Oxidation-Reduction Reaction!?

Question

Please help me balance this oxidation-reduction reaction using the half reaction method!

PbO +NH3 ---> N2 + Pb

I cant seem to find which one is getting oxidized and which is getting reduced!

Thanks

Answer 1

Pb (+2) + 2e -> Pb (0)  |x3

2N (-3) -> N2 (0) - 6e    |x1

-> 3Pb0 + 2NH3 -> N2 + 3Pb + 3H20

You seem to forget H20 somehow. That 's why it can't be done

Answer 2

Lead is getting reduced (goes from +2 to 0) and nitrogen is getting oxidized (goes from -3 to 0).  With these numbers, we start the balancing process by writing 3PbO + 2NH3 -> N2 + 3Pb + 3H2O, and discover that there is nothing more to do.