1. Tardigrade
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  3. Chemistry
  4. The dissociation constant of a weak base is 1 × 10-5 at 25°C. The pH of its 0.1 M solution at the same temperature. will be .

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Q. The dissociation constant of a weak base is $1 \times 10^{-5}$ at $25°C$. The pH of its $0.1\, M$ solution at the same temperature. will be .

COMEDKCOMEDK 2011Equilibrium

Solution:

By Ostwald dilution law,
$\left[ OH ^{-}\right]$in weak base $=\sqrt{K_b C}$
$=\sqrt{1 \times 10^{-5} \times 0.1}$
$=1 \times 10^{-3} M$
$pOH =-\log [ OH -]=-\log \left(1 \times 10^{-3}\right)$
$pOH =3 \Rightarrow pH + pOH =14$
$\Rightarrow pH =14-3=11$