Question

An oxyacid of phosphorus has the following properties: The complex neutralisation of the acid with sodium hydroxide solution given an aqueous solution of sodium ions and oxy-acid anions in the ratio 2:1. When a solution of the acid is warmed with silver nitrate solution, metallic silver is deposited.

$pH$ 0.01 M solution of the sodium salt of this acid formed (assume $p{K}_{a_1}=2x$) is___________.

• A. 6+2x
• B. 6-2x
• C. 6-x
• D. 6+x

Answer 1

The correct option is D 6+x

As we know,

$pH=7+\frac{p{K}_a}{2}+\frac{logC}{2}$

$pH=7+\frac{2x}{2}+\frac{log\left[0.01\right]}{2}$

$=7+\frac{2x}{2}-1=(6+x)$

Therefore pH 0.01 M solution of the sodium salt of this acid formed is $(6+x)$