Question

Check whether the reaction $H_{2}S+S{O}_2\to H_{2}O+S$ is a redox reaction or not? If yes, what will be the oxidant?

• A. Yes, ${SO}_2$
• B. Yes, $S$
• C. Yes, $H_{2}S$
• D. No, this is not redox

Answer 1

The correct option is A

Yes, ${\mathrm{SO}}_2$

Explanation:

Redox reaction:

• A reaction in which oxidation and reduction take place simultaneously is called a redox reaction.
• The given equation is:

${\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)+{\mathrm{SO}}_2\left(g\right)\to {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+\mathrm{S}\left(\mathrm{s}\right)$

Analyze the given reaction:

• In the given reaction, the oxidation state of Sulfur ($\mathrm{S}$) changes from +4 in Sulphur dioxide (${\mathrm{SO}}_2$) to zero in $\mathrm{S}$. Hence, ${\mathrm{SO}}_2$ is getting reduced.
• Similarly, the oxidation state of $\mathrm{S}$ changes from -2 in Hydrogen sulfide (${\mathrm{H}}_2\mathrm{S}$) to zero in $\mathrm{S}$. Hence, ${\mathrm{H}}_2\mathrm{S}$ is getting oxidized.
• Since reduction and oxidation take place simultaneously, the given reaction is a redox reaction.

Identify the oxidant in the reaction:

• The substances which have the ability to oxidize others and get reduced by themselves are known as oxidizing agents or oxidants. Whereas the substances which have the ability to reduce others and get oxidized by themselves are known as reducing agents or reductants.
• Since ${\mathrm{SO}}_2$ is getting reduced thus, it is the oxidizing agent or oxidant in the reaction.

Hence, option (A) is correct. Yes, the reaction is a redox reaction and ${\mathrm{SO}}_2$ is the oxidant.