Question

Consider the following decomposition reaction
$2KCl{O}_3⟶2KCl+3O_2$
In the above reaction,

• A. potassium is undergoing oxidation
• B. chlorine is undergoing reduction
• C. oxygen is reduced
• D. None of the species are undergoing oxidation or reduction

Answer 1

Answer: (B)

$\stackrel{+1+5-2}{2KClO{)}_3}⟶\stackrel{+1-1}{2KCl}+3\stackrel{0}{O_2}$
(a) The oxidation number of $K$ does not change, thus $K$ undergoes neither reduction nor oxidation.
(b) The oxidation number of chlorine decreases from $+5$ in $KCl{O}_3$ to $-1$ in $KCl$, hence $Cl$ undergoes reduction.
(c) Since, oxidation number of oxygen increases from $-2$ in $KCl{O}_3$ to 0 in $O_2$, so oxygen is oxidised.
(d) This statement is not correct because $Cl$ is undergoing reduction and $O$ is undergoing oxidation.
Therefore, statement (b) is true about the given reaction.