Oxidation:
According to the classical concept, oxidation is a process of addition of oxygen or removal of hydrogen.
Removal of hydrogen
$$
2 \mathrm{H}_{2} \mathrm{~S}-\mathrm{O}_{2} \rightarrow \mathrm{H}_{2} \mathrm{O}+2 \mathrm{~S}
$$
Addition of oxygen \(\mathrm{C}-\mathrm{O}_{2} \rightarrow \mathrm{CO}_{2}\)
According to the electronic concept, loss of electrons is called oxidation reaction.
$$
\mathrm{Ca} \rightarrow \mathrm{Ca}^{2+}+2 \mathrm{e}^{-}
$$
During oxidation, oxidation number increases.
Dining oxidation, reducing agent gets oxidised.
Reductlon:
Reduction is a process of removal of oxygen or addition of hydrogen. Addition of hydrogen
$$
\mathrm{Ca}+\mathrm{H}_{2} \rightarrow \mathrm{CaH}_{2}
$$
Removal of oxygen
$$
\mathrm{Zn} \mathrm{O}+\mathrm{C} \rightarrow \mathrm{Zn}+\mathrm{CO}
$$
According to the electronic concept, gain of electrons is called reduction reaction.
$$
\mathrm{Zn}^{2+}-2 \mathrm{e}^{-} \rightarrow \mathrm{Zn}
$$
During reduction, oxidation number decreases.
During reduction, oxidising agent gets reduced.
