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MHT CET · Chemistry · Ionic Equilibrium

The degree of dissociation of a \(0.01 \mathrm{M}\) weak acid is \(10^{-3}\). Its \(\mathrm{pOH}\) is

  1. A \(\underline{5}\)
  2. B 3
  3. C 9
  4. D 11
Verified Solution

Answer & Solution

Correct Answer

(C) 9

Step-by-step Solution

Detailed explanation

\(\left[\mathrm{H}^{+}\right]=\sqrt{K_{a} \cdot C}=139\)
Or \(=\sqrt{\alpha^{2} \cdot C^{2}} \quad\left[\therefore K_{a}=\alpha^{2} C\right]\)
\(= \sqrt{\left(10^{-3}\right)^{2} \cdot(0.01)^{2}} \)
\( = 10^{-5} \)
\( \mathrm{pH}=-\log \left[\mathrm{H}^{+}\right] =-\log 10^{-5} \)
\( =5\)
\(\mathrm{pOH}=14-5=9\)