2021 · Q10
When copper reacts with moist carbon dioxide (CO ) in air, it forms a green coating of which 2 one of the following compounds?
General KnowledgeChemistry
- ACupric carbonate
- BCuprous oxide
- CCupric oxide
- DCopper sulphate
Explanation
Copper exposed to moist air containing carbon dioxide develops a green patina of basic copper carbonate, CuCO3.Cu(OH)2, commonly called verdigris and loosely termed cupric carbonate. Cuprous oxide is red, cupric oxide is black, and copper sulphate is a blue soluble salt - none matches the green coating. The green layer is therefore cupric carbonate.