Question

Identify the substances that are oxidised and that are reduced in the following equation.

1. $4Na(s) + {O_2}(g) \to 2N{a_2}O(s)$
2. $CuO(s) + {H_2}(g) \to Cu(s) + {H_2}O(l)$

Answer 1

Oxidation-reduction (redox) reactions are important because they are the main primary natural, biological, and man made energy sources. By eliminating hydrogen and replacing it with oxygen, oxidation of molecules usually releases a lot of energy.

Complete answer:
The substance that loses electrons is being oxidized and is known as the reducing agent. The substance that gains electrons is being reduced and is known as the oxidizing agent.
$4Na(s) + {O_2}(g) \to 2N{a_2}O(s)$
In the above reaction the oxidized substance is $Na$ and the reduced substance is ${O_2}$ .
In the reaction, sodium ($Na$) is getting oxidized with the addition of Oxygen (${O_2}$).
$CuO(s) + {H_2}(g) \to Cu(s) + {H_2}O(l)$
In the above reaction the oxidized substance is ${H_2}$ and the reduced substance is $CuO$
In the reaction copper ($Cu$) is reduced due to the addition of Hydrogen (${H_2}$).
Oxidation occurs when a reactant loses electrons during a process. Reduction occurs when a reactant acquires electrons during a reaction. This is a common phenomenon when metals react with acid. Oxidation occurs when a reactant loses electrons during a process. Reduction occurs when a reactant acquires electrons during a reaction.

Note:
A reduction-oxidation reaction, also known as a redox reaction, is a chemical reaction in which both reduction and oxidation take place at the same time. The electrons are given to the reduced species, whereas they are taken away from the oxidised species. Despite its name, an oxidation process does not require the presence of oxygen.