Question

22. 1 g of copper powder was taken in a China dish and heated. What change
takes place on heating? When hydrogen gas is passed over this heated
substance, a visible change is seen in it. Give the chemical equations of
reactions, the name and the color of the products formed in each case.​

Answer 1

The chemical reactions are:

2Cu + O₂ → 2CuO

CuO + H₂ → Cu +H₂O

When copper powder is heated in a china dish, in the presence of oxygen, a black residue is formed on the dish due to the formation of copper(II) oxide.

This phenomenon is known as surface oxidation.

The followiing reaction is shown below.

2Cu + O₂ → 2CuO

Again when CuO is treated with hydrogen gas, CuO gets reduced to Cu, a brown residue.

CuO + H₂ → Cu +H₂O

Answer 2

Explanation:

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