JEE Advanced · 2014 · 25 May 2014 · Paper 2 · p-Block Elements

When thionyl chloride (${\mathrm{SOCl}}_2$) reacts with white phosphorus (${\mathrm{P}}_4$), it acts as a chlorinating agent. The reaction produces phosphorus trichloride (${\mathrm{PCl}}_3$) along with sulfur dioxide (${\mathrm{SO}}_2$) and sulfur. The reaction is:

${\mathrm{P}}_4+8{\mathrm{SOCl}}_2\to 4{\mathrm{PCl}}_3+4{\mathrm{SO}}_2+2{\mathrm{S}}_2{\mathrm{Cl}}_2$

The main product is ${\mathrm{PCl}}_3$.