Ncert Exercises & Solutions

What will be the value of pH of $0.01 mol {dm}^{- 3} {CH}_{3} COOH$ $(K_{a} = 1.74 \times 10^{- 5})$ ?

(1) 3.4

(2) 3.6

(3) 3.9

(4) 3.0

Hint:

[H^{+}] = \sqrt{K_{a} . C}

Given that,

(K_{a} = 1.74 \times 10^{- 5})

Concentration of

{CH}_{3} COOH = 0.01 mol {dm}^{- 3}

[H^{+}] = \sqrt{K_{a} . C} = \sqrt{1.74 \times 10^{- 5} \times 0.01} = 4.17 \times 10^{- 4} pH = - \log [H^{+}] = - \log (4.17 \times 10^{- 4}) = 3.4