We are being asked to **calculate the K _{b} for a 0.1 M weak base (HB)**.

**Step 1. Equilibrium reaction:** **HB _{(aq)} + H_{2}O_{(l)} **

$\overline{){{\mathbf{K}}}_{{\mathbf{b}}}{\mathbf{=}}\frac{\mathbf{products}}{\mathbf{reactants}}{\mathbf{=}}\frac{\left[{\mathrm{BH}}_{2}\right]\left[{\mathrm{OH}}^{-}\right]}{\left[\mathrm{HB}\right]}}$

${\mathbf{K}}_{\mathbf{b}}\mathbf{=}\frac{\left[\mathbf{x}\right]\left[\mathbf{x}\right]}{\left[\mathbf{0}\mathbf{.}\mathbf{1}\mathbf{-}\mathbf{x}\right]}\phantom{\rule{0ex}{0ex}}\overline{){{\mathbf{K}}}_{{\mathbf{b}}}{\mathbf{=}}\frac{{\mathbf{x}}^{\mathbf{2}}}{\mathbf{0}\mathbf{.}\mathbf{1}\mathbf{-}\mathbf{x}}}$

The pH of a 0.10 M solution of a weak base is 9.82. What is the Kb for this base?

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Weak Bases concept. If you need more Weak Bases practice, you can also practice Weak Bases practice problems.