Question

Give a reason for the following:

${\mathrm{PCl}}_5$ acts as an oxidising agent.

Answer 1

${\mathrm{PCl}}_5$ acts as an oxidising agent:-

• At first, we have to what is phosphorus's oxidation state.
• The oxidation state of chlorine as we know is -1.
• Let its oxidation state be $x$,

$$\begin{gathered} \therefore x+(-5)=0 \\ \Rightarrow x-5=0 \\ \Rightarrow x=5 \end{gathered}$$

• Now we know this fact that oxidation state of phosphorus can be only $+3$ and$+5$, and here its$+5$.
• As a result, we can see that phosphorus cannot donate electrons, hence it cannot acts as a reducing agent.
• Thus +5 oxidation state of phosphorus pentachloride ${\mathrm{PCl}}_5$ is more stable than +3, which results ${\mathrm{PCl}}_5$in acting as an oxidising agent.