The pH of 0.10 N acetic acid having Ka=1.8 × 10-5 is

Question

The pH of 0.10 N acetic acid having Ka=1.8 × 10-5 is (A) 2.9 (B) 5.6 (C) 6.8 (D) 3.4

Tardigrade Admin · Accepted Answer

<img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/chemistry/3f6fd358fa09d7429e3fbf6f7c77828b-.png" /> ∴ [ H +]=C α or C ⋅ √(Ka/C)=√Ka C [∵ α=√(Ka/c)] ⇒√1.8 × 10-5 × 0.1 =1.34 × 10-3 M ⇒ pH =- log [ H +] =- log (1.34 × 10-3)=2.9

Q. The $p H$ of $0.10 N$ acetic acid having $K_{a} = 1.8 \times 1 0^{- 5}$ is

$2.9$

$5.6$

$6.8$

$3.4$

$∴ [H^{+}] = C α$
or $C \cdot \frac{K _{a}}{C} = K_{a} C$
$[∵ α = \frac{K _{a}}{c}]$
$\Rightarrow 1.8 \times 1 0^{- 5} \times 0.1$
$= 1.34 \times 1 0^{- 3} M$
$\Rightarrow p H = - lo g [H^{+}]$
$= - lo g (1.34 \times 1 0^{- 3}) = 2.9$

Q. The pH of 0.10N acetic acid having Ka​=1.8×10−5 is

2.9

5.6

6.8

3.4