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Chemistry · EQUILIBRIUM
हिन्दीThe solubility of a salt \( \text{MX} \) of a weak monobasic acid \( \text{HX} \) depends on pH according to the relation \( S = \sqrt{K_{sp}(1 + \frac{[\text{H}^+]}{K_a})} \). If \( K_{sp} = 4.0 \times 10^{-10} \) and \( K_a = 1.0 \times 10^{-5} \), what is the molar solubility of \( \text{MX} \) at \( \text{pH} = 3.0 \)?
Correct answer · Option 3
\( 2.01 \times 10^{-4}\text{ M} \)
Explanation
At \( \text{pH} = 3.0 \), \( [\text{H}^+] = 10^{-3}\text{ M} \). \( \frac{[\text{H}^+]}{K_a} = \frac{10^{-3}}{10^{-5}} = 100 \). So \( 1 + \frac{[\text{H}^+]}{K_a} = 101 \). \( S = \sqrt{4.0 \times 10^{-10} \times 101} = \sqrt{4.04 \times 10^{-8}} \approx 2.01 \times 10^{-4}\text{ M} \).
