Question

Solid phosphorous pentachloride behaves as an ionic compound. Explain. Why?

Answer 1

Solid $PC{l}_5$ exists as $\left[PC{l}_4^{+}\right]\left[PC{l}_6^{-}\right]$. Thus we can see there are two ions present, phosphorus tetrachloride which is positively charged and phosphorus hexachloride which is negatively charged.

Due to the presence of these ions, a solid $PC{l}_5$ behaves as an ionic compound.

$PC{l}_5$ is used for the chlorination of organic compounds. It must be kept under desiccator as on absorbing moisture it forms phosphorus oxychloride.