Nitrogen oxides summary

FormulaOxidation state
of N		PreparationReaction with water 

N2O		+1careful heating of
NH4NO3(s)*		none 
NO+2NH3 + O2 **
Pt catalyzed		none 

N2O3
ON–NO2		avge
+3		cool
NO + NO2  → 
KNO2 + H+ →		HNO2
(nitrous acid)		 

NO2***		+4NO + O2 → NO2→ HNO3(nitric acid) + NO 

N2O4
(O2N–NO2)		+4cool NO2→ HNO3(nitric acid) + NO 

N2O5
(O2N–O–NO2)		+5HNO3 + P4O10→ HNO3
(nitric acid)		 

*If NH4NO3 is not carefully heated N2 is formed instead of N2O.

**If no catalyst is present, N2 is formed instead of NO.

***Although both NO2 and NO are odd electron molecules, only NO2 dimerizes readily.
Dr Sheila Woodgate
© The University of Auckland 2002