Question

State why nitric acid is a strong oxidising agent and yields varying products such as NO, NO₂ on reaction with metals,non-metals etc.

Answer 1

The oxidising property of nitric acid is based on the fact that when nitric acid undergoes decomposition, it yields nascent oxygen, which is very reactive.

2HNO₃ (cone.) → H₂O + 2NO₂ + [O] 

2HNO₃ (dil.) → H₂O + 2NO + 3[O]

This nascent oxygen oxidises metals, non-metals, organic and inorganic compounds. During the process, nitric acid itself gets reduced to various products (NO, NO₂ , N₂O, NH₃ , etc.) depending upon the concentration of the acid, reaction temperature and activity of the metal with which it is reacting.