Question

Why does phosphoric acid react with three times more than sodium hydroxide, when the solutions are mixed to form the salt?

• A. It is highly soluble
• B. It has 3 hydrogen to be replaced
• C. It is insoluble
• D. Both $B$ and $C$

Answer 1

The correct option is B It has 3 hydrogen to be replaced

Phosphoric acid produces three protons per acid molecule. Hence, there are three hydrogen (H) that has to be replaced by the metal ion. Therefore, phosphoric acid will react with three times as much as sodium hydroxide to form the salt, trisodium phosphate(V).
$H_{3}P{O}_4+3NaOH\to N{a}_{3}P{O}_4+3H_{2}O$