Question

Define the terms oxidation, reduction, oxidant and reductant in terms of electron transfer.

Answer 1

Hint: zinc loses two electrons and forms $Z{{n}^{2+}}$. Zinc undergoes oxidation to form \[Z{{n}^{+2}}\].
\[\begin{align}
& Zn-2{{e}^{-}}\xrightarrow{{}}Z{{n}^{2+}} \\
& Zn\xrightarrow{{}}Z{{n}^{+2}}+2{{e}^{-}} \\
\end{align}\]
Cupric ions gain two electrons and form copper. Cupric ion undergoes Reduction to form copper.
$Zn+C{{u}^{2+}}\xrightarrow{{}}Z{{n}^{2+}}+Cu$
Cupric ions are oxidant and zinc is reductant in this example.

Complete step by step solution:
Consider Zinc loses two electrons and forms Zinc ion. Oxidation number of zinc elements in free state is 0 and the oxidation number of zinc in zinc ion is +2, so there is an increase in oxidation state of zinc during loss of electrons.
\[\begin{align}
& Zn-2{{e}^{-}}\xrightarrow{{}}Z{{n}^{2+}} \\
& Zn\xrightarrow{{}}Z{{n}^{2+}}+2{{e}^{-}} \\
\end{align}\]
This loss of electron or increase in oxidation state is known as Oxidation.
Consider Cupric ion gains two electrons to form copper. The oxidation number of copper in cupric ion is +2 and the oxidation number of copper elements in a free state is 0, so there is a decrease in oxidation state.
This gain of electrons and decrease in oxidation state is known as reduction.
A reaction in which simultaneously oxidation and reduction takes place is called a redox reaction.
-$Zn+C{{u}^{+2}}\xrightarrow{{}}Cu+Z{{n}^{2+}}$
In this reaction, zinc is losing two electrons and undergoes oxidation and cupric ion accepts two electrons and cupric ion undergoes reduction.
So, Cupric ion is acting as oxidant as an oxidant is that substance which gains electrons and zinc is reductant as reductant is a substance which loses electrons.

Note: when there is a loss of electron or increase in oxidation state, the process is called oxidation. When there is an electron or decrease in oxidation state, the process is called reduction. Substance losing electrons is reductant and substance gaining electrons is an oxidant. A reaction in which simultaneously oxidation and reduction takes place is called a redox reaction.