Question

The number of ionizable hydrogens present in the product obtained from a reaction of phosphorus trichloride and phosphonic acid is

• A. $3$
• B. $1$
• C. $0$
• D. $2$

Answer 1

The correct option is D

$2$

The explanation for the correct option:

A: $2$

The reaction of Phosphorus trichloride and Phosphonic acid:

• When the Phosphorus trichloride $\left({\mathrm{PCl}}_3\right)$ reacts with the Phosphonic acid$\left({\mathrm{H}}_3{\mathrm{PO}}_3\right)$, the Diphosphoric acid$\left({\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_5\right)$ is formed as the product.$\underset{\left(\mathrm{Phosphorus}\mathrm{trichloride}\right)}{{\mathrm{PCl}}_3}+\underset{\left(\mathrm{Phosphonic}\mathrm{acid}\right)}{{\mathrm{H}}_3{\mathrm{PO}}_3}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}}\to \underset{\left(\mathrm{Diphosphoric}\mathrm{acid}\right)}{{\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_5}+\underset{\left(\mathrm{Hydrochloric}\mathrm{acid}\right)}{\mathrm{HCl}}$

Determine the number of ionizable hydrogens:

• The Diphosphoric acid$\left({\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_5\right)$ can be broken down into $2{\mathrm{H}}^{+}$ and ${\mathrm{H}}_2{\mathrm{P}}_2{{\mathrm{O}}_5}^{--}$ ion.
• It means there are two ionizable hydrogens present in the product Diphosphoric acid$\left({\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_5\right)$.