91Ó°ÊÓ

Complete and balance the following reaction for the weak acid HOCl: $$\mathrm{HOCl}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell) \rightleftharpoons$$ Write the equilibrium expression for the \(K_{\mathrm{a}}\) of HOCl.

Complete and balance the following reaction for the weak base pyridine: $$\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{~N}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O} \rightleftharpoons$$ Write the equilibrium expression for the \(K_{\mathrm{b}}\) of \(\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{~N}\).

The \(K_{b}\) of \(\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{~N}\), at \(25^{\circ} \mathrm{C}\), is \(1.7 \times 10^{-9}\). Find " \(x\) " (CTQ 13), and enter the equilibrium concentration values in the last row of the following table. $$\begin{array}{|l|c|c|c|} \hline & \mathrm{C}_{5} \mathrm{H}_{5} \mathrm{~N} & \mathrm{OH}^{-} & \mathrm{C}_{5} \mathrm{H}_{5} \mathrm{NH}^{+} \\ \hline \text { initial moles } & 0.30 & 0 & 0 \\ \hline \text { change in moles } & & & \\ \hline \text { equilibrium moles } & & & \\ \hline \begin{array}{l} \text { equilibrium conc. } \\ \text { expression } \end{array} & & & \\ \hline \begin{array}{l} \text { equilibrium conc. } \\ \text { value } \end{array} & & & \\ \hline \end{array}$$ Verify that your equilibrium concentrations are correct.

For a weak acid, why is \(\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]=\left[\mathrm{A}^{-}\right] ?\)

A \(0.50 \mathrm{M}\) solution of \(\mathrm{CH}_{3} \mathrm{COOH}\) has \(\left[\mathrm{CH}_{3} \mathrm{COO}^{-}\right]=3.0 \times 10^{-3} \mathrm{M}\). What are the values of: \(\left(\mathrm{CH}_{3} \mathrm{COOH}\right)_{0}=\) \(\left[\mathrm{CH}_{3} \mathrm{COOH}\right]=\) \(\left[\mathrm{H}_{3} \mathrm{O}^{+}\right] \quad=\) \(K_{\mathrm{a}} \quad=\)