Question

Choose the most correct answer :

The solubility product of a sparingly soluble salt AX is 5.2 × 10^–13. Its solubility in mol dm^–3 is ______.

Options

• 7.2 × 10^–7

• 1.35 × 10^–4

• 7.2 × 10^–8

• 13.5 × 10^–8

Answer 1

The solubility product of a sparingly soluble salt AX is 5.2 × 10^–13. Its solubility in mol dm^–3 is `bb(underline(7.2 xx 10^-7))`.

Explanation:

K_sp = 5.2 × 10^–13

\[\ce{\underset{s}{AX} ⇌ \underset{s}{A}^{-} + \underset{s}{X}^{+}}\]

K_sp = [A^–][X⁺]

= s × s

5.2 × 10^–13 = s²

`sqrt(10^-13) = sqrt(10^-12)` = 10^–6

0.52 × 10^–12 = s²

`sqrt(0.52 xx 10^-12)` = s

0.7211 × 10^–6 = s

s = 7.211 × 10^–7