Remember that ** weak bases** partially dissociate in water and that

**Equilibrium reaction:** **R-NH _{2}**

**Step 1:**** **Construct an ICE chart for the reaction.

**Step 2:** Write the K_{b} expression and calculate for K_{b}.

$\overline{){{\mathbf{K}}}_{{\mathbf{b}}}{\mathbf{=}}\frac{\mathbf{products}}{\mathbf{reactants}}}\phantom{\rule{0ex}{0ex}}{\mathbf{K}}_{\mathbf{b}}\mathbf{=}\frac{\mathbf{[}\mathbf{R}\mathbf{-}{{\mathbf{NH}}_{\mathbf{3}}}^{\mathbf{+}}\mathbf{]}\mathbf{\left[}{\mathbf{OH}}^{\mathbf{-}}\mathbf{\right]}}{[R-{\mathrm{NH}}_{2}]}$

*Solids and liquids are not included in the expression*

**Step 3:**** **Calculate the equilibrium concentrations.

What is the pH of 0.32 M R-NH_{2} (amine - a weak base) with a K_{b} of 6.43x10^{-6} at 21°C? Enter pH to 2 decimal places.

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