The oxidation state of N in NH4NO3 is
-3
+5
Oxidation number of N in NH4NO3
If we go by the usual method N2H4O3;2X+4×(+1)+3×(−2)=0
2X+4−3=0 or X=+1 (wrong)
No doubt N2H4O3 has two Nitrogen atoms. One N has negative oxidation number (attached to H) and the other has positive oxidation number (attached to O). Hence the evolution should be made separately for NH+4 and NO−3.
For the oxidation number of N in ammonium ion, NH+4: x+4×(+1)=+1 or x=−3
For NO−3 x+3×(−2)=−1 or x=+5