Question

Which electrode: anode or cathode is the oxidising electrode? Why?

Answer 1

• The reaction in which one or more electrons is lost by a species is called an oxidation reaction.
• In the oxidation process, the oxidation number of a substance increases by the loss of electrons. Example,

$\underset{\mathrm{Zinc}}{\mathrm{Zn}\left(\mathrm{s}\right)}\to \underset{\mathrm{Zinc}\mathrm{ion}}{{\mathrm{Zn}}^{2+}\left(\mathrm{aq}\right)}+2{\mathrm{e}}^{-}$

• The oxidation number of Zinc (Zn) is 0 in Zn and +2 in Zn²⁺. Therefore, the loss of electrons results in an increase in the oxidation number of Zinc which implies that oxidation takes place.
• In electrolytic cells, the conversion of electrical energy into chemical energy takes place. It consists of two electrodes, an anode, and a cathode.
• Anode is a positively charged electrode while the cathode is a negatively charged electrode.
• Since there is an attraction between negatively charged electrons and positively charged anode, the electrons lost during oxidation will accumulate at the anode.
• Hence, an anode is termed an oxidizing electrode.