NEET UG 2005 — Chemistry Physical Chemistry

$$\begin{gathered} \mathrm{C}=0.01 \mathrm{M} \\ \mathrm{K}_b=1 \times 10^{-12} \text { at } 25^{\circ} \mathrm{C} \\ \mathrm{BOH} \rightleftharpoons \mathrm{B}^{+}+\mathrm{OH}^{-} \\ \mathrm{C} \quad 0 \quad 0 \end{gathered}$$C=0.01MKb​=1×10−12 at 25∘CBOH⇌B++OH−C00​ at eq. $\mathrm{C}-\mathrm{C} \alpha \mathrm{C} \alpha \mathrm{C} \alpha$C−CαCαCα $$\begin{aligned} {\left[\mathrm{OH}^{-}\right] } & =\mathrm{C} \alpha \\ {\left[\mathrm{OH}^{-}\right] } & =\sqrt{\mathrm{K}_b \mathrm{C}}=\sqrt{1 \times 10^{-12} \times 10^{-2}} \end{aligned}$$[OH−][OH−]​=Cα=Kb​C​=1×10−12×10−2​​ $$\left[\mathrm{OH}^{-}\right]=10^{-7} \mathrm{~mol} \mathrm{~L}^{-1}$$[OH−]=10−7 mol L−1 Related Theory The activities of the solutes are approximated with molarities. The dissociation constant is an immediate consequence of the law of mass action which describes equilibria in a more general way. The dissociation constant is also sometimes called ionization constant when applied to salts.