Question

239. In the following list of salts, identify normal, acid and basic salts

(b) Na₃PO₄

Answer 1

• The salts which are formed by the partial neutralization of a diprotic or polyprotic acid are termed acidic salts. They form an acidic solution on hydrolysis.
• The salts which are produced by the partial neutralization of a strong base with a weak acid are termed basic salts. They form a basic solution on hydrolysis.
• The salts in which all the H⁺ ions are replaced by metal ions or hydroxide ions are replaced by acid radicals are termed normal salts.
• Sodium phosphate ( Na₃PO₄) is made up of Phosphoric acid (H₃PO₄) and Sodium hydroxide (NaOH).

$\underset{\mathrm{Phosphoric}\mathrm{acid}}{{\mathrm{H}}_3{\mathrm{PO}}_4}+\underset{\mathrm{Sodium}\mathrm{hydroxide}}{3\mathrm{NaOH}}\to \underset{\mathrm{Sodium}\mathrm{phosphate}}{{\mathrm{Na}}_3{\mathrm{PO}}_4}+\underset{\mathrm{Water}}{3{\mathrm{H}}_2\mathrm{O}}$

• It does not contain any hydrogen (H⁺) or hydroxide ion (OH^-).

Hence, Sodium phosphate ( Na₃PO₄) is a normal salt.