Question

Why do copper vessels lose their shine when exposed to air?

Answer 1

One of the main reason why the copper vessels lose their shine when exposed to air is due to the passivization.

When copper forms as protective layer of oxidation on the surface for preventing the further deterioration then material would be around the normal condition.

At the surface of vessel, Copper atoms react with the Oxygen atoms in the air forming copper-oxide.

Answer 2

When the copper forms as protective layer of oxidation on the surface at the surface of vessel,copper atoms react with oxygen and the calles copper oxide