Question

Giving two examples, explain the concept of oxidation and reduction on the basis of loss or gain of electrons.

Answer 1

• The process of oxidation involves the loss of one or more electrons from an atom or ion.
• In the oxidation process, the oxidation number of a substance increases by the loss of electrons.
• Example, Iron(III) ion (${\mathrm{Fe}}^{3+}$) is formed by the loss of one electron (${\mathrm{e}}^{-}$) from Iron(II) ion (${\mathrm{Fe}}^{2+}$).
• ${\mathrm{Fe}}^{2+}\to {\mathrm{Fe}}^{3+}+{\mathrm{e}}^{-}$
• The oxidation number of Iron ($\mathrm{Fe}$) is +2 in ${\mathrm{Fe}}^{2+}$ and +3 in ${\mathrm{Fe}}^{3+}$. Therefore, the loss of electrons results in an increase in the oxidation number of $\mathrm{Fe}$ which implies that oxidation takes place.
• The process of reduction involves the gain of one or more electrons by an atom or ion.
• In the reduction process, the oxidation number of a substance decreases by the gain of electrons.
• Example, Zinc ($\mathrm{Zn}$) is formed by the gain of two electrons (${\mathrm{e}}^{-}$) by Zinc(II) ion (${\mathrm{Zn}}^{2+}$).
• ${\mathrm{Zn}}^{2+}+2{\mathrm{e}}^{-}\to \mathrm{Zn}$
• The oxidation number of $\mathrm{Zn}$ is +2 in $Z{n}^{2+}$and 0 in $\mathrm{Zn}$. Therefore, the gain of electrons results in a decrease in the oxidation number of $\mathrm{Zn}$ which implies that reduction takes place.