Question

Which salt can not furnish $H^{+}$ in its aqueous solution?

• A. $Na{H}_{2}P{O}_2$
• B. $N{a}_{2}HP{O}_3$
• C. $N{a}_{2}HP{O}_4$
• D. $Allofthese$

Answer 1

The correct option is D $Allofthese$

${Na}_{2}HP{O}_3$ is formed when the two acidic hydrogens are replaced by sodium. In other words, this salt is the product of complete neutralisation of phosphoric acid by sodium hydroxide. It does not have any acidic hydrogen. So, it is a normal sodium salt of phosphorus acid.

In case of $Na{H}_{2}P{O}_2$ hydroxides of phosphorus presence of P—OH / P—O(-) bond refers to the acidic character. So in the case of $H_{2}P{O}_2(-)$, there is only 1 P—O(-) bond. Thus it has a basicity = 1. Since Na(+) also has an acidity of 1 and both $H_{3}P{O}_2$(conjugate acid) and Na(conjugate base) are strong acid and base respectively, both neutralize each other resulting in a neutral/normal salt.

In ${Na}_{2}HP{O}_4$+2$H_{2}O\to 2Na+H_{3}P{O}_4+2O{H}^{-1}$

$H_{3}P{O}_4$ being a weak acid will not dissociate to give $H^{+1}$ ion.

All the salt cannot furnish H+ ion in aqueous solution.