Chemical And Ionic Equilibrium Result Question 29
29. A certain weak acid has a dissociation constant of $1.0 \times 10^{-4}$.
The equilibrium constant for its reaction with a strong base is
(1984, 1M)
(a) $1.0 \times 10^{-4}$
(b) $1.0 \times 10^{-10}$
(c) $1.0 \times 10^{10}$
(d) $1.0 \times 10^{14}$
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Answer:
Correct Answer: 29. ( c )
Solution:
- The reaction of $\mathrm{H} A$ with strong base is
$\begin{aligned} & \mathrm{H} A+\mathrm{OH}^{-} \rightleftharpoons \mathrm{H}_2 \mathrm{O}+A^{-} \\ & \qquad K=\frac{\left[A^{-}\right]}{[\mathrm{H} A]\left[\mathrm{OH}^{-}\right]} \times \frac{\left[\mathrm{H}^{+}\right]}{\left[\mathrm{H}^{+}\right]}=\frac{K_a}{K_w}=\frac{10^{-4}}{10^{-14}}=10^{10} \end{aligned}$
BETA
