Question

The pH of a 0.32 mol/L weak base solution is 9.8. Calculate the Kb of this base.

Answer 1

Answer to Question #58552, Chemistry / Other

The pH of a 0.32 mol/L weak base solution is 9.8. Calculate the Kb of this base.

Solution:

Weak base react with water:

$$\mathrm{B} + \mathrm{H_2O} \rightarrow \mathrm{HB^+} + \mathrm{OH^-}$$ $$K_b = \frac{[\mathrm{HB^+}][\mathrm{OH^-}]}{[B]}$$ $$[\mathrm{HB^+}] = [\mathrm{OH^-}] = 10^{-(14 - \mathrm{pH})}$$ $$K_b = \frac{(6.31 \times 10^{-5})^2}{0.32 - 6.31 \times 10^{-5}} = 1.24 \times 10^{-8}$$

Answer:

$$1.24 \times 10^{-8}$$

http://www.AssignmentExpert.com/