Question

What happens when?
(A) Copper powder is heated in china dish
(B) Hydrogen gas is passed over hot copper II oxide

Answer 1

Hint : Copper is the chemical element present in the periodic table with an atomic number $29$ . It has a symbol – Cu. It is a soft metal and is malleable and ductile. It also has a high thermal and electrical conductivity. Also it is seen that the freshly exposed copper surface is slightly pinkish-orange in colour.

Complete Step By Step Answer:
There are two parts given in the question and this is important to note that both the reactions are opposite to each other. So let’s have a look separately on t=both the reactions.
When Copper powder is heated in china dish-
So when the copper is heated in the china dish exposed to oxygen i.e. exposed to air, the copper reacts with the oxygen to form the oxide of copper i.e copper oxide.
Let’s also have a look at the chemical reaction of the above process.
Therefore the reaction is:
$2Cu + {O_2} \to 2CuO$
The copper oxide formed in the reaction is black in colour. And this black colour coating resulted because of the oxidation reaction of the copper.
When Hydrogen gas is passed over hot copper II oxide- so, when the hydrogen gas is passed over the hot copper II oxide, the Copper oxide decomposes back to the copper. As a result of which the black colour formed in the above reaction turns to the brown colour.
Let’s have a look at the chemical equation:
$CuO + {H_2} \to Cu + {H_2}O$ .

Note :
By heating copper powder in a china dish we refer to the process that the copper is heated in the china dish in the presence of oxygen. And this oxidation reaction results in the production of black colour coating of copper on the china dish.