Question

Why do coppers turn green when exposed to moist air?(60 words)

Answer 1

Copper metal when exposed to air turns green in colour due to corrosion. When copper vessel is exposed to air in rainy season, the metal reacts with gases and moisture and atmospheric gases to form a mixture of copper carbonate and copper hydroxide. This gives a green colour to the surface of copper metal.  

The reaction is as follows:

2Cu + H2O + CO2 + O2 →  Cu(OH)2  +  CuCO3

Answer 2

Copper turns green because of chemical reactions with the element Just as iron that is left unprotected in open air will corrode and form a flaxy 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 .