Question

Explain the following: H₃PO₃ is diprotic acid.

Answer 1

If you see the structure of H3PO3, you will see that, 2H atoms are attached to O atoms whereas 1H is directly attached to the central atom, P.

Due to more electronegativity difference between H and O, the H atom attached to O is detached rather than the H attached to P. So, when H3PO3 is added to water, only 2H+ ions are released.

And that's why H3PO3 is a diprotic or dibasic acid.

Thanks. :)