Question

What is the basicity of ${\mathrm{H}}_3{\mathrm{PO}}_3$?

Answer 1

Phosphorous acid

• The chemical name of ${\mathrm{H}}_3{\mathrm{PO}}_3$ is phosphorus acid. It is an oxyacid.

Basicity

• The basicity is a measure of the ability to accept a proton $\left({\mathrm{H}}^{+}\right)$ to form a stable product.

Basicity of acid

• The Basicity of an acid is defined as the number of replaceable hydrogen atoms of that particular acid by a base.

Basicity of ${\mathrm{H}}_3{\mathrm{PO}}_3$

• Only those $\mathrm{H}$atoms which are attached with oxygen in $\mathrm{P}–\mathrm{OH}$ form are ionizable and cause the basicity.
• The structure of ${\mathrm{H}}_3{\mathrm{PO}}_3$ is as follows:-

• In the above structure, only two $\mathrm{H}$atoms are attached with oxygen.
• So, ${\mathrm{H}}_3{\mathrm{PO}}_3$ is dibasic, and basicity of ${\mathrm{H}}_3{\mathrm{PO}}_3$ is $2$.