Question

Which among the following oxoacids of phosphorus shows a tendency of disproportionation?

• A. Phosphinic acid $\ce{(H_3PO_2)}$
• B. Orthophosphoric acid $\ce{(H_3PO_4)}$
• C. Phosphonic acid $\ce{(H_3PO_3)}$
• D. Pyrophosphoric acid $\ce{(H_4P_2 O_7)}$

Answer 1

Answer: (C)

Phosphonic acid $\ce{(H_3PO_3)}$

Answer 2

Phosphonic acid $\left( H _{3} PO _{3}\right)$, oxoacid of phosphorus shows a tendency of disproportionation. On heating $H _{3} PO _{3}$ disproportionates to give orthophosphoric acid and phosphene gas.

$4 H _{3} PO _{3} \stackrel{ \Delta }{\longrightarrow} 3 H _{3} PO _{4}+ PH _{3}$