A weak base is $1.42 \%$ dissociated in its $0.05 \mathrm{M}$ solution. Calculate its dissociation constant.

A weak base is $1.42 \%$ dissociated in its $0.05 \mathrm{M}$ solution. Calculate its dissociation constant.
  1. $5.5 \times 10^{-5}$
  2. $4.0 \times 10^{-5}$
  3. $1.8 \times 10^{-5}$
  4. $1.0 \times 10^{-5}$

Solution

Percent dissociation $=1.42 \%$ $\therefore \quad \alpha=0.0142$ For a weak monoacidic base, $\begin{aligned} \mathrm{K}_{\mathrm{b}} & =\alpha^2 \mathrm{C} \\ & =(0.0142)^2 \times(0.05) \\ & =1.0082 \times 10^{-5} \end{aligned}$

Asked in: MHT CET 2023 (11 May Shift 2)

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