Question

The solubility of a sparingly soluble salt Ax By in water at 25ºC = 1.4 × 10–4 M. The solubility product is 1.1 × 10–11. The possibilities are

• A. x = 1, y = 2
• B. x = 2, y = 1
• C. x = 1, y = 3
• D. x = 3, y = 1

Answer 1

Answer: (A)

x = 1, y = 2

Answer 2

Ksp = 1.1 × 10–11 = (1.4 × 10–4)x + y xx . yy

so we have x + y = 3 (by comparing values)

so, xx . yy = $\frac{1.1 \times 10^{- 11}}{1.4 \times 1.4 \times 1.4 \times 10^{- 12}}$ = $\frac{110}{1.96 \times 1.4}$ = 4

Hence x = 1, y = 2 or

y = 1 , x = 2