Need help with ONE redox equation with BASIC solution.?

Question

Can someone please help me balance this equation:

NO2- (aq) + Al(s) ==> NH3(g) + AlO2- (aq)

Answer 1

This is a redox problem, so solve each half-reaction separately.

Aluminum is being oxidized:
4OH- + Al ----> AlO2- + 2H2O + 3e-
Nitrogen is being reduced:
6e- + 5H2O + NO2- ----> NH3 + 7OH-
Multiply the first reaction by 2 to balance the electrons:
8OH- + 2Al ----> 2AlO2- + 4H2O + 6e-
Sum the two half-reactions together and cancel the common species to give you the final balanced reaction in basic solution:
OH- + H2O + NO2- + 2Al -----> NH3 + 2AlO2-