Question

Give a reason for the following.

Phosphoric acid is a tribasic acid.

Answer 1

Tribasic acid - The acids which produce three hydrogen ions per molecule when dissolved in water are called tribasic acids.

For example - Phosphoric acid.

• Molecular formula - ${\mathrm{H}}_3{\mathrm{PO}}_4$
• The tribasic nature of phosphoric acid can be shown by the following reaction-

$$\begin{gathered} {\mathrm{H}}_3{\mathrm{PO}}_4\left(\mathrm{l}\right)\rightleftharpoons 3{\mathrm{H}}^{+}+{\mathrm{PO}}_4^{3-} \\ (\mathrm{Phosphoric}(\mathrm{Hydrogen}(\mathrm{Phosphate} \\ \mathrm{acid})\mathrm{ion})\mathrm{ion}) \end{gathered}$$

Since Phosphoric acid produce three hydrogen ions per molecule when dissolved in water , hence it is a tribasic acid.