Question

Reason and reaction why copper turns green ​

Answer 1

Answer :

★ Corrosion of copper -

Copper turns green (attain a green coat) when it is exposed to moist air for a long time. This happens due to corrosion of copper.

When copper reacts with moist carbon dioxide in the air it corrodes to form a mixture of copper hydroxide and copper carbonate. This mixture gives the surface of copper metal/article a green color/coat.

★ Reaction for the formation of green coat :

$\bold{2Cu+H_2O+CO_2+O_2\longrightarrow{}Cu(OH)_2+CuCO_3}$

$\rule{200}2$

★ Some other cases of corrosion :

• Silver articles corrodes and become black after some time when it is exposed to air. This happens because silver reacts with sulphur in the air to form a black coat of silver sulphide.

• Iron corrodes when it is exposed to moist air for a long time. This results in a coating of a brown flaky substance called rust.

Answer 2

Copper turns green

(attain a green coat) when it is exposed to moist air for a long time. This happens due to corrosion of copper. When copper reacts with moist carbon dioxide in the air it corrodes to form a mixture of

copper hydroxide and copper carbonate.