Question

The sodium salt of a certain weak monobasic organic acid is hydrolysed to an extent of 3% in its 0.1M solution at 250C. Given that the ionic product of water is 10-14 at this temperature, what is the dissociation constant of the acid?

• A. » 1 x 10-10
• B. » 1 x 10-9
• C. 3.33 x 10-9
• D. 3.33 x 10-10

Answer 1

Answer: (A)

» 1 x 10-10

Answer 2

h = .03 C = 0.1 M

Kh = Ch2 = 9 × 10–5

Kh =$\frac{K_{W}}{K_{a}}$ = 9 × 10–5

$\Rightarrow$ Ka = $\frac{10^{- 14}}{9 \times 10^{- 5}}$= 1.11 × 10–10 $\approx$ 1 × 10–10