Question

Consider the following reaction:
$6NaOH+3C{l}_2\to 5NaCl+A+3H_{2}O$

What is the oxidation number of chlorine in $A$?

• A. $+5$
• B. $-1$
• C. $+3$
• D. $+1$

Answer 1

The correct option is A $+5$

Balancing the above equation, the formula of $A$ is $NaCl{O}_3$.

Since, $Na$ is highly electropositive, it has an oxidation number of $+1$.

Hence, the $Cl{O}_3$ group has an oxidation number of $-1$.

We also know that the oxidation number of oxygen in $Cl{O}_3$ is $-2$, since it is more electronegative than chlorine.

Let the oxidation number of $Cl$ in $Cl{O}_3$ be $x$.

Therefore,
$x-3\left(2\right)=-1$
or, $x-6=-1$
Therefore, $x=+5$

The oxidation number of $Cl$ in $NaCl{O}_3$ be $+5$.