Question

At 25°C, the solubility product of MCl is \(1 \times 10^{-10}\). What is its molar solubility in 0.1 M NaCl solution at the same temperature?

• A. 0.1 M
• B. 0.05 M
• C. \(10^{-9}\) M
• D. \(10^{-5}\) M

Hint:

In presence of a common ion, the solubility of a salt decreases and can be calculated using \(s = K_\text{sp}/[\text{common ion}]\).

Answer 1

The Correct Option is C

Step 1: Apply the common-ion effect.
NaCl provides 0.1 M Cl\(^-\). For MCl: \(K_{sp} = [M^+][Cl^-] = s \times 0.1 = 10^{-10}\).

Step 2: Solve for s.
\(s = \frac{10^{-10}}{0.1} = 10^{-9}\) M.
\[ \boxed{10^{-9}\text{ M}} \]