4H(+1)N+5)O(-2)3 + Ni(0)=Ni(+2) (N(+5)O(-2)3)2+2N(+4)O(-2)2+2H(+1)2O(-2) Ni(0) -2e = Ni(+2) 2 1 N(+5) +1e= N(+4) 1 2