Classical Idea of Redox Reactions - Oxidation and Reduction Reactions

"Oxidation" is defined as the addition of oxygen/electronegative element to a substance or the removal of hydrogen/ Electron/ electropositive element from a substance.

or

A process involving an increase in oxidation number by the loss of electrons.

"Reduction" is defined as the removal of oxygen/ electronegative element from a substance or the addition of hydrogen/Electron/ electropositive element to a substance.

or

A process involving decrease in oxidation number by gain of electrons.

The species which gets itself reduced and oxidise another species is called oxidising agent.

or

A substance which involves a decrease in the oxidation number of one or more of its elements. An oxidising agent helps oxidise the other substance by being reduced itself.

\[\begin{aligned} & \mathrm{S}+6\mathrm{HNO}_{3}\longrightarrow\mathrm{H}_{2}\mathrm{SO}_{4}+2\mathrm{H}_{2}\mathrm{O}+6\mathrm{NO}_{2} \\ & \mathrm{Oxidising} \\ & \mathrm{agent} \end{aligned}\]

The species which gets itself oxidised and reduce another species is called reducing agent.

or

A substance which involves an increase in the oxidation number of one or more of its elements. A reducing agent helps reduce the other substance by being oxidised.

\[\begin{aligned} & \mathrm{ZnO}+\mathrm{C}\longrightarrow\mathrm{Zn}+\mathrm{CO} \\ & \mathrm{Reducing} \\ & \mathrm{agent} \end{aligned}\]