Question

You might have noted that when copper powder is heated in a china dish, the reddish brown surface of copper powder becomes coated with a black substance.
(a) Why has this black substance formed ?
(b) What is this black substance ?
(c) Write the chemical equation of the reaction that takes place.
(d) How can the black coating on the surface be turned reddish brown?

Answer 1

Answer:

Explanation:

A) because it react with o2

B) Cuo

C) Cu+ O--->. Cuo

D) by adding H2 to Cup

Thank you

Answer 2

Oxidation of copper

Explanation:

(a) Oxidation of copper causes the black coloured substance to be formed.

(b) Copper (II) oxide is the black substance.

(c) 2Cu + O2 --> 2CuO

Copper combines with oxygen to form copper oxide. This results in the change of colour from red to black on the top layer of the exposed copper.

(d) When hydrogen is passed over it, hydrogen displaces oxygen from copper oxide. So the reddish brown colour of copper can be restored.

CuO + H2—–> Cu + H2O