1. Copper(II) Nitrate: When copper reacts with dilute nitric acid (typically 1-3 M), it forms copper(II) nitrate, which is a blue-green crystalline compound. The reaction can be represented as follows:
Cu(s) + 4HNO3(dilute) → Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l)
In this reaction, copper is oxidized from its elemental state (Cu(s)) to the +2 oxidation state in copper(II) nitrate (Cu(NO3)2). Nitrogen dioxide (NO2) gas is produced as a byproduct, along with water (H2O).
2. Copper(II) Oxide: When copper reacts with concentrated nitric acid (usually above 6 M), it can form copper(II) oxide, which is a black powder. The reaction can be represented as follows:
Cu(s) + 4HNO3(concentrated) → CuO(s) + 4NO2(g) + 2H2O(l)
In this reaction, copper is oxidized to the +2 oxidation state in copper(II) oxide (CuO). Nitrogen dioxide (NO2) gas is produced as a byproduct, along with water (H2O).
It's important to note that the reaction between copper and nitric acid can be vigorous, especially with concentrated acid, and should be carried out with proper safety precautions and under controlled conditions.
