1)
3FexOy + (12x-2y)HNO3→3xFe(NO3)3+(3x-2y)NO+(6x-y)H2O
2)
FexOy + (6x-2y) HNO3 = x Fe(NO3)3 + (3x-2y) NO2+(3x-y) H2O
3)
8FexOy + (30x-4y)HNO3 -> 8xFe(NO3)3 + (3x-2y)N2O + (15x-2y)H2O
4)
10FexOy + (36x-4y)HNO3 → 10xFe(NO3)3 + (3x-2y)N2 + (18x-2y)H2O