Why is PCl3 acidic?

Question

Why is it that when adding PCl3 into distilled water, the solution becomes acidic? What exactly is the reaction occurring? Must it not be neutral as the PCl3 is molecular, or then P has a lone pair of electrons, so is it not a Lewis base?

Answers in here may give some insights. – Mathew Mahindaratne May 13 '22 at 17:48 — Mathew Mahindaratne, May 13 '22 at 17:48
Can you prepare an aqueous solution of $\ce{PCl3}$? – user55119 May 13 '22 at 20:18 — user55119, May 13 '22 at 20:18

Waylander · Answer 1 · 2022-05-13T10:48:39.950

3

According to this source here

Phosphorus trichloride (phosphorus chloride, PCl3) is a colorless fuming liquid that reacts violently with water to liberate phosphorous acid (H3PO3) and hydrogen chloride (HCL) gas.

The oxygen of water attacks the P atom, which is positively polarised because of the 3 electronegative chlorines attached to it.

The HCl gas dissolves in the water to give hydrochloric acid so the resulting solution contains 2 strong acids.

edited May 13 '22 at 10:48

answered May 13 '22 at 08:59

Waylander

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Hey thanks loads! But why does it give HCl and phosphoric acid? – jack Morgan May 13 '22 at 09:23
The citation says phosphorous acid, not phosphoric acid. – user55119 May 14 '22 at 13:36
If you go to the source linked it incorrectly says phosphoric acid – Waylander May 14 '22 at 15:30

Why is PCl3 acidic?

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