Question

What happen when copper vessel is exposed to moist air for a long time? Give the chemical reaction that takes place

Answer 1

Copper turns green because of chemical reactions with the elements. Just as iron that is left unprotected in open air will corrode and form a flaky orange-red outer layer, copper that is exposed to the elements undergoes a series of chemical reactions that give the shiny metal a pale green outer layer called a patina.
Cu+O2------------>CuO

Answer 2

State. Answer: Copper forms a green deposit on its surface when exposed to air which is usually a mixture of copper carbonate and copper hydroxide.