When sulphuryl chloride $\left( SO _{2} Cl _{2}\right)$ reacts with white phosphorus $\left( P _{4}\right)$, it give phosphorus pentachloride $\left( PCl _{5}\right)$ and' sulphur dioxide $\left( SO _{2}\right)$. The reaction is as follows:
$P _{4}+10\, SO _{2} Cl _{2} \longrightarrow 4 PCl _{5}+10 SO _{2}$