The equation 6HNO3 + 3Cu2S -> 3Cu(NO3)2 + 3H2O + 6NO + 3SO2

1. Detailed Information on the Equation:

The chemical equation above describes the reaction between nitric acid (HNO₃) and copper sulfide (Cu₂S) to form copper (II) nitrate (Cu(NO₃)₂), water (H₂O), nitrogen oxide (NO) and sulfur dioxide (SO₂).

In this equation, the mole ratio between the reactants and products is represented as: 6 moles of HNO₃ react with 3 moles of Cu₂S to form 3 moles of Cu(NO₃)₂, 3 moles of H₂O, 6 moles of NO, and 3 moles of SO₂.

2. Reaction Conditions:

This reaction requires the presence of a heat source to initiate. Nitric acid needs to be used in concentrated form and copper sulfide needs to be heated.

3. Reaction Process:

When copper sulfide is placed in a concentrated nitric acid environment and heated, it is oxidized by HNO₃ to form copper (II) nitrate, water, nitrogen oxide and sulfur dioxide.

4. Observed Phenomena:

During the reaction, a reddish-brown smoke will appear due to the formation of nitrogen oxide. The initial black color of copper sulfide will change to the blue color of copper (II) nitrate. In addition, there may be a characteristic smell of sulfur dioxide.