Question

15. 1g of copper powder was taken in a China dish and heated. What change takes place on heating? When hydrogen
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.
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Answer 1

Answer:

What change takes place on heating? When hydrogen gas is passed over this heated substance, a visible change is seen in it.

Answer 2

Answer:

When 1g of copper powder is taken in a china dish and heated, a black coloured substance is formed. This substance is copper oxide.

(Red brown)

2Cu

+

(From air)

O

2

Heat

(Black)

2CuO

The copper gets oxidized to copper oxide.

When hydrogen gas is passed over this heated substance, CuO, copper metal is obtained.

The black-coloured CuO is reduced and brown colour Cu metal is produced.

(Black)

CuO

+

(Hydrogen gas)

H

2

⟶

Brown

Cu(s)

+H

2

O(l)