Question

$K_a$ for cyano acetic acid is $3.5{10}^{-3}$. Then the degree of hydrolysis of $0.05M$ sodium cyano acetate solution will have the value:

• A. $4.559\times {10}^{-6}$
• B. $5.559\times {10}^{-6}$
• C. $6.559\times {10}^{-6}$
• D. $7.559\times {10}^{-6}$

Answer 1

Answer: (D)

Given: Degree of hydrolysis= $0.05M$

$K_a$ for cyno acetic acid= $3.5\times {10}^{-3}$

Solution: The degree of hydrolysis is given by,

=$\sqrt{\frac{K_w}{K_{a}c}}$

Substituting the values we get,

$\sqrt{\frac{1\times {10}^{-14}}{3.5\times {10}^{-3}\times 0.05}}$ ($K_w$=$1\times {10}^{-14}$)

On solving we get,

$7.559\times {10}^{-6}$

Hence, the correct option is (D).