Question

Which chemical phenomenon is responsible for a green coating on the copper coins.Write the chemical name of the coating on the copper coins. How can we remove this green coating ? What methods can we use to save the coins from further deterioration?
(class 10 CBSE SAMPLE PAPER 2017-18 SCIENCE)

Answer 1

Corrosion is responsible for the green coating over the coins. Copper object remains in damp air for a considerable time then copper reacts slowly with the carbon dioxide and water of air to form a green coating.
The Green coating on the copper coins is of basic copper carbonate. The green coating of basic copper carbonate is a mixture of copper carbonate and copper hydroxide CuCO3.Cu(OH)2.
We can remove this green coating by cleaning the coins with vinegar solution.
We can save the coins from for the deterioration by protecting the coins from air and moisture. This can be done by using the coins with a layer of oil or Vaseline.

HOPE THIS WILL HELP YOU....

Answer 2

Answer:

The chemical name is basic copper carbonate.

We can remove the green coating by adding dillute acid solution like vinegar.

This solution dissolves the green layer present be on the corroded copper object