Hydrolysis of NCl3 and PCl3

Introduction
NCl3 and PCl3 are both covalent compounds that can undergo hydrolysis reactions in the presence of water. However, they react differently due to the different electronic structures and bonding properties of nitrogen and phosphorus.

Electronic Structure and Bonding
- Nitrogen (N) has 5 valence electrons, while phosphorus (P) has 5 valence electrons.
- Nitrogen forms three covalent bonds in NCl3, resulting in a trigonal pyramidal shape with a lone pair of electrons.
- Phosphorus forms three covalent bonds in PCl3, yielding a trigonal pyramidal shape as well but without any lone pairs.

Hydrolysis of NCl3
- NCl3 reacts with water in a hydrolysis reaction.
- The lone pair of electrons on nitrogen acts as a Lewis base and donates electrons to the electrophilic hydrogen atom of water.
- This forms a coordinate bond between nitrogen and hydrogen, resulting in the formation of NH4+ ion and Cl- ion.
- The reaction proceeds as follows: NCl3 + 3H2O → NH4+ + 3Cl-
- The NH4+ ion is acidic and can further react with water to form H3O+ and NH3.
- The overall reaction can be represented as: NCl3 + 4H2O → NH3 + 3HCl + H3O+

Hydrolysis of PCl3
- PCl3 also undergoes hydrolysis, but the reaction is less vigorous compared to NCl3.
- PCl3 reacts with water to form phosphorous acid (H3PO3) and hydrochloric acid (HCl).
- The reaction proceeds as follows: PCl3 + 3H2O → H3PO3 + 3HCl
- The presence of the lone pair of electrons on nitrogen in NCl3 enhances its reactivity towards water, leading to a more exothermic and rapid hydrolysis reaction.

Conclusion
In summary, NCl3 and PCl3 hydrolyze differently due to the presence of a lone pair of electrons on nitrogen in NCl3, which makes it more reactive towards water. The lone pair on nitrogen acts as a Lewis base and forms a coordinate bond with the electrophilic hydrogen of water, leading to the formation of NH4+ and Cl- ions. On the other hand, PCl3 undergoes a less vigorous hydrolysis reaction, resulting in the formation of phosphorous acid (H3PO3) and hydrochloric acid (HCl).