Question

What is a redox reaction? In the reaction $ZnO + C \to Zn + CO$ which substance gets oxidised and which gets reduced?

Answer 1

In order to answer this question, first we will explain the whole phenomenon of the redox reaction and we will also discuss the redox reaction is known as Oxidation-reduction reaction and then we will discuss, in the given reaction, which element is oxidised and which one is reduced.

Complete answer: $*$ An oxidation-reduction reaction is any chemical reaction in which the oxidation numbers (oxidation states) of the atoms are changed. Redox reactions, which is shorthand for reduction-oxidation processes, are another name for these types of reactions.
The oxidation number increases during oxidation, while the oxidation number decreases during reduction. The loss or gain of electrons is usually connected with a change in oxidation number, but some redox reactions (such as covalent bonding) do not entail electron transfer.
Oxidation and reduction can entail any of the following for a given atom, ion, or molecule, depending on the chemical reaction:
(i) The loss of electrons or hydrogen OR the uptake of oxygen OR the increase in oxidation state are all examples of oxidation.
(ii) The addition of electrons or hydrogen OR the loss of oxygen OR the decrease in oxidation state are all examples of reduction.
$*$ In the given reaction: $ZnO + C \to Zn + CO$
$C$ is oxidised since it has lost electrons.
And, $Zn$ is reduced since it has gained electrons.

Note:
To balance the charges of the redox reaction:-
Step-1: Establish the oxidation states of the species in question. Because the charges do not yet equal, the equation is not balanced. Each half-reaction can be used to balance the charges. Because the Cl-ions are spectator ions and do not participate in the actual redox process, they drop out.
Step-2: Write the half reactions.