Equilibrium Ques 60
60. Accumulation of lactic acid $(HC_3 H_5 O_3)$, a monobasic acid in tissues leads to pain and a feeling of fatigue. In a $0.10$ $ M$ aqueous solution, lactic acid is $3.7 \%$ dissociated. The value of dissociation constant, $K_a$, for this acid will be:
[NEET Kar. 2013]
(a) $2.8 \times 10^{-4}$
(b) $1.4 \times 10^{-5}$
(c) $1.4 \times 10^{-4}$
(d) $3.7 \times 10^{-4}$
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Answer:
Correct Answer: 60.(c)
Solution:
- (c) $\alpha=\sqrt{\frac{K_a}{c}}=0.037=\sqrt{\frac{K_a}{0.10}}$;
$ \begin{aligned} K_a & =(0.037)^{2} \times 0.10=1.37 \times 10^{-4} \\ & \simeq 1.4 \times 10^{-4} \end{aligned} $
BETA
