Why are the modes of hydrolysis of NCl3 and PCl3 different?

Answer 1

The N - Cl bond is only slightly polar, with the greater electron density on the nitrogen. Hydrolysis is thought to be initiated by nucleophilic attack of a water molecule on the chlorine. Phosphorus trichloride hydrolysis proceeds by the normal later-period method of water attacking the central phosphorus atom. This is possible because phosphorus has readily available d-orbitals in the valency shell. Second period elements such as nitrogen lack these and that is why many of their compounds are resistant to hydrolysis.

Answer 2

The modes of hydrolysis of NCl3 and PCl3 are different because of the different electronegativities of nitrogen and phosphorus. NCl3 hydrolyzes to produce ammonia and hydrochloric acid due to the higher electronegativity of nitrogen, while PCl3 hydrolyzes to produce phosphorous acid and hydrogen chloride because phosphorus is less electronegative. This difference in electronegativity affects the reactivity of the compounds with water.