Consider the following reactions: $\mathrm{PCl}_{3}+\mathrm{H}_{2}\mathrm{O} \longrightarrow \mathrm{A}+\mathrm{HCl}$ $\mathrm{A}+\mathrm{H}_{2}\mathrm{O} \longrightarrow \mathrm{B}+\mathrm{HCl}$ number of ionisable protons present in the product B ______.

JEE Main · 2022 · 25 Jun 2022 · Shift 2 · p-Block Elements

Consider the following reactions:

PCl_{3} + H_{2} O ⟶ A + HCl

A + H_{2} O ⟶ B + HCl

number of ionisable protons present in the product B ______.

Answer: 2

Solution

Partial hydrolysis of

PCl_{3}

gives phosphorous acid derivatives. The first reaction produces

PCl_{2} (OH)

(A). Further hydrolysis gives phosphorous acid

H_{3} PO_{3}

(B), which has the structure with two P-OH groups and one P-H bond. Only the two hydroxyl protons are ionizable, giving 2 ionizable protons.

JEE Main · 2022 · 25 Jun 2022 · Shift 2 · Integer answer

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