Question

What happens when copper vessel is exposed to moist air for long time ? State
whether the corroded coating of copper acidic or basic.

Answer 1

Explanation:

When copper vessel is exposed to moist air for long period of time then it undergoes various chemical reactions. As the metal reacts with various chemicals and gases present in the atmosphere and it results in the formation of copper carbonate which is green in color.

The reaction will be as follows.

  $2Cu + H_{2}O + CO_{2} + O_{2} \rightarrow Cu(OH)_{2}+ CuCO_{3}$

Hence, the corroded coating of green color is copper carbonate which is basic in nature.  

Answer 2

When copper vessel is exposed to moist air for long time it develops a green layer on its surface. Copper oxide then combined with carbon dioxide to make copper carbonate which gives it a green colour