Question

What happens when ${\mathrm{PCl}}_5$ is heated?

Answer 1

Phosphorus pentachloride

• Phosphorus pentachloride $\left({\mathrm{PCl}}_5\right)$ has three equatorial $\mathrm{P}-\mathrm{Cl}$ bonds and two axial $\mathrm{P}-\mathrm{Cl}$ bonds.
• When strongly heated, ${\mathrm{PCl}}_5$ decomposes to form its trihalide.

Structure of Phosphorus pentachloride

Heating Phosphorus pentachloride

• When Phosphorus pentachloride $\left({\mathrm{PCl}}_5\right)$ gas is heated, it produces phosphorus trichloride $\left({\mathrm{PCl}}_3\right)$ gas and chlorine $\left({\mathrm{Cl}}_2\right)$ gas.
• The chemical reaction is as follows:

$\underset{\left(\mathrm{Phosphorus}\mathrm{pentachloride}\right)}{{\mathrm{PCl}}_5\left(\mathrm{g}\right)}\rightleftharpoons \underset{\left(\mathrm{Phosphorus}\mathrm{trichloride}\right)}{{\mathrm{PCl}}_3\left(\mathrm{g}\right)}+\underset{\left(\mathrm{Chlorine}\right)}{{\mathrm{Cl}}_2\left(\mathrm{g}\right)}$