Question

In the reaction $PC{l}_3+S{O}_3\to POC{l}_3+S{O}_2,PC{l}_3$ acts as __ agent.

Answer 1

$PC{l}_3+S{O}_3\to POC{l}_3+S{O}_2$

The theoretical oxidation state of P in $PC{l}_3$ is +3 isn’t it? It changes to +5 in Phosphoryl chloride.

Look at the oxidation states of Sulphur in $S{O}_3$ and $S{O}_2$. It is respectively +6 and +4. Hence PCl₃ is a reducing agent and $S{O}_3$ is an oxidizing agent.