Question

What is a redox reaction? Explain with the help of an example.

Answer 1

Redox reaction- A reaction in which reduction and oxidation take place simultaneously is called a redox reaction.

Oxidation is defined as-

• Addition of oxygen to a substance, or
• Removal of hydrogen from a substance, or
• Loss of electrons.

Oxidizing agent-

• A substance in the chemical reaction which provides oxygen for oxidation of another substance. or,
• A substance in the chemical reaction which removes hydrogen from another substance for its oxidation.
• Gains electrons and is reduced in a chemical reaction.

Reduction is defined as-

• Addition of hydrogen to a substance, or
• Removal of oxygen from a substance, or
• Gain of electrons

Reducing agent-

• A substance in the chemical reaction which removes oxygen from another substance for its reduction.
• A substance in the chemical reaction which provides its hydrogen for the reduction of another substance.
• Loses electrons and is oxidized in a chemical reaction.

$\underset{\mathrm{Zinc}}{\mathrm{Zn}\left(\mathrm{s}\right)}+\underset{\mathrm{Copper}\mathrm{sulphate}}{{\mathrm{CuSO}}_4\left(\mathrm{aq}\right)}\to \underset{\mathrm{Zinc}\mathrm{sulphate}}{{\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Copper}}{\mathrm{Cu}\left(\mathrm{s}\right)}$

• Let us understand the exchange of electrons taking place in the reaction by writing two half-reactions-
• Oxidation: $\mathrm{Zn}\left(\mathrm{s}\right)\to {\mathrm{Zn}}^{2+}\left(\mathrm{aq}\right)+2{\mathrm{e}}^{-}$
• Zinc is losing electrons to form zinc cation.
• Reduction: ${\mathrm{Cu}}^{2+}\left(\mathrm{aq}\right)+2{\mathrm{e}}^{-}\to \mathrm{Cu}\left(\mathrm{s}\right)$
• Copper is gaining electrons to form neutral atoms.

• In the given reaction Zinc placed in Copper sulfate solution displaces Copper and forms Zinc sulfate solution.
• Oxidation- Zinc is being oxidized as it is losing 2 electrons to form a Zinc cation.
• Oxidizing agent- Copper is an oxidizing agent as it is gaining 2 electrons.
• Reduction- Copper is being reduced as it is gaining 2 electrons to get its neutral atoms in a solid state.
• Reducing agent- Zinc is the reducing agent here as it is losing electrons in the reaction.