Sketch the titration curve for the titration of a generic weak base \(\mathrm{B}\) with a strong acid. The titration reaction is $$ \mathrm{B}+\mathrm{H}^{+} \rightleftharpoons \mathrm{BH}^{+} $$ On this curve, indicate the points that correspond to the following: a. the stoichiometric (equivalence) point b. the region with maximum buffering c. \(\mathrm{pH}=\mathrm{p} K_{\mathrm{a}}\) d. \(\mathrm{pH}\) depends only on \([\mathrm{B}]\) e. \(\mathrm{pH}\) depends only on \(\left[\mathrm{BH}^{+}\right]\) f. \(\mathrm{pH}\) depends only on the amount of excess strong acid added

In this titration, a weak base \(\mathrm{B}\) is titrated with a strong acid. The titration reaction is: \[ \mathrm{B}+\mathrm{H}^{+} \rightleftharpoons \mathrm{BH}^{+} \] Initially, only the weak base is present in the solution. As we add the strong acid, the weak base is converted into its conjugate acid, \(\mathrm{BH}^{+}\). This causes a change in pH throughout the titration process.

The stoichiometric (equivalence) point is reached when the moles of \(\mathrm{H}^+\) added equals the initial moles of \(\mathrm{B}\). At this point, all the weak base has been converted into its conjugate acid, and the pH can be calculated using the weak acid's \(K_{\mathrm{a}}\).

The region with maximum buffering occurs when the solution can resist changes in pH to the greatest extent. This occurs when a solution contains equal concentrations of \(\mathrm{B}\) and \(\mathrm{BH}^{+}\), resulting in a pH close to the \(pK_{\mathrm{a}}\) value of the conjugate acid.

At the point where \(\mathrm{pH}=\mathrm{p} K_{\mathrm{a}}\), there are equal concentrations of the weak base, \(\mathrm{B}\), and its conjugate acid, \(\mathrm{BH}^{+}\).

Initially, when only the weak base is present in the solution, the pH depends only on the concentration of the weak base, \([\mathrm{B}]\). This is before any strong acid has been added.

At the stoichiometric point, all of the weak base has been converted into its conjugate acid, \(\mathrm{BH}^{+}\). So, at this point, the pH depends only on the concentration of the conjugate acid, \(\left[\mathrm{BH}^{+}\right]\).

Beyond the stoichiometric point, the pH depends only on the excess strong acid that has been added, as all the weak base has been converted to its conjugate acid and does not affect the pH any further.

Now, we'll sketch the titration curve and indicate the points described above: - The initial pH (before adding any strong acid) depends only on \([\mathrm{B}]\) (point d). - The region with maximum buffering occurs at \(\mathrm{pH}=\mathrm{p} K_{\mathrm{a}}\), where there are equal concentrations of \(\mathrm{B}\) and \(\mathrm{BH}^{+}\) (point a, b, and c). - At the stoichiometric point, the pH depends only on \(\left[\mathrm{BH}^{+}\right]\) (point e). - Beyond the stoichiometric point, the pH depends only on the amount of excess strong acid added (point f). In summary, the titration curve will start with a pH dependent on the initial concentration of \(\mathrm{B}\), then reach maximum buffering around the \(pK_{\mathrm{a}}\) value, moving on to the stoichiometric point where pH depends on the conjugate acid concentration, and finally, the pH will become dependent on the excess strong acid added.