Question

What happens when:
(a) copper powder is heated in china dish
(b) hydrogen gas is passed over hot copper(III) oxide?

Answer 1

To answer the given statement, you should properly know about the chemical reactions of the copper and about their reactants formed after the reaction and after that you can easily solve the given reactions accordingly.

Complete answer:
First of all, let’s discuss copper. Copper is a metal which comes under the category of the d-block elements i.e. the transition metals and has the atomic number as 29 and the mass number as 64.
Now considering the statement as-
(a) when copper metal is made to heat in the china dish in the presence of the oxygen gas it results in the formation of the oxide i.e. the copper oxide. The reaction is supposed to take place as-
$2Cu+{{O}_{2}}\to 2CuO$
Now coming to the next part-
(b) when this copper oxide is formed to react with the hydrogen gas, it again results in the formation of the copper i.e. the reaction is reversed. The chemical reaction is supposed to occur as-
$CuO+{{H}_{2}}\to Cu+{{H}_{2}}O$
So, thus when copper powder is heated in a china dish, it forms copper oxide and when hydrogen gas is passed over hot copper(III) oxide, it again results in the formation of the copper.

Note:
The copper oxide formed in the first reaction is black in color. The black color is formed due to the oxidation of the copper by the oxygen and when the hydrogen gas is passed over this, the black coating again changes to the brown and thus reverts the reaction.