Question

On adding dilute hydrochloric acid to copper oxide powder, the solution formed is blue-green.

1. Predict the new compound formed which imparts a blue-green colour to solution.
2. Write a balanced chemical equation of the reaction which takes place.
3. On the basis of the above reaction, what can you say about the nature of copper oxide?

Answer 1

1. When cupric oxide is treated with dilute hydrochloric acid, copper(II) chloride (a blue-green salt solution) and water are obtained.
2. \[\ce{CuO_{(s)} + 2HCl_{(aq)} -> CuCl_{(aq)} + H2O_{(l)}}\]
3. Based on the above reaction, copper oxide is basic in nature. It is a metallic oxide that neutralises the acid to form a corresponding salt (copper chloride) and water, behaving similarly to a standard base.