Illustrate how copper metal can give different products on reaction with HNO3.
Illustrate how copper metal can give different products on reaction with HNO3.

Concentrated nitric acid acts as a strong oxidizing agent. It is used for the oxidation of most metals.
The products of oxidation depend on certain parameters such as temperature, concentration of the acid, and also on the material of the substance undergoing oxidation. The reactions can be written as:

    \[3Cu\text{ }+\text{ }8HN{{O}_{3}}\left( \text{ }dil. \right)\to 3Cu{{(N{{O}_{3}})}_{2~}}+\text{ }2NO\text{ }+\text{ }4{{H}_{2}}O\]


    \[Cu\text{ }+\text{ }4HN{{O}_{3}}\left( \text{ }conc.\text{ } \right)~\to Cu{{(N{{O}_{3}})}_{2}}~+\text{ }2N{{O}_{2}}~+2{{H}_{2}}O\]