The hydrogen ion concentration of 0.1 M hydrocyanic acid is 6.3 × 10-6 M , the Ka is

Question

The hydrogen ion concentration of 0.1 M hydrocyanic acid is 6.3 × 10-6 M , the Ka is (A) 3.96 × 10-10 (B) 3.78 × 10-9 (C) 3.86 × 10-8 (D) 3.70 × 10-11

Tardigrade Admin · Accepted Answer

[ H +]=6.3 × 10-6 M α ' degree of dissociation =([ H +]/C)=(6.3 × 10-6/0.1)=6.3 × 10-5 According to Ostwald's formula for weak electrolyte, Ka=α2 C=(6.3 × 10-5)2 × 0.1=3.96 × 10-10

Q. The hydrogen ion concentration of $0.1 M$ hydrocyanic acid is $6.3 \times 1 0^{- 6} M,$ the $K_{a}$ is

$3.96 \times 1 0^{- 10}$

$3.78 \times 1 0^{- 9}$

$3.86 \times 1 0^{- 8}$

$3.70 \times 1 0^{- 11}$

$[H^{+}] = 6.3 \times 1 0^{- 6} M$

$α$ ' degree of dissociation $= \frac{[ H ^{+} ]}{C} = \frac{6.3 \times 1 0 ^{- 6}}{0.1} = 6.3 \times 1 0^{- 5}$

According to Ostwald's formula for weak electrolyte,

$K_{a} = α^{2} C = (6.3 \times 1 0^{- 5})^{2} \times 0.1 = 3.96 \times 1 0^{- 10}$

Q. The hydrogen ion concentration of 0.1M hydrocyanic acid is 6.3×10−6M, the Ka​ is

3.96×10−10

3.78×10−9

3.86×10−8

3.70×10−11