Sketch two pH curves, one for the titration of a weak acid with a strong base and one for a strong acid with a strong base. How are they similar? How are they different? Account for the similarities and the differences.

: A pH curve for the titration of a weak acid (HA) with a strong base (B) typically has the following key features: - It starts with a higher initial pH (due to the weak acid's lower initial H₃O⁺ concentration) - The curve is more gradual during in the buffer region (where the acidic and basic forms are in equilibrium) - The pH curve has a slower rise near the equivalence point and is not as sharp. - The equivalence point has a pH > 7, due to the formation of a weak conjugate base (A⁻). During the titration, the strong base (B) will react with the weak acid (HA) to form a conjugate weak base (A⁻) and a neutral salt (BH). The overall equation for the reaction is: HA + B → A⁻ + BH

: A pH curve for the titration of a strong acid (HX) with a strong base (B) generally has the following key features: - It starts with a lower initial pH (due to the strong acid's higher initial H₃O⁺ concentration) - The curve has a very sharp rise around the equivalence point. - The equivalence point has a pH of 7, as the resulting solution only consists of neutral species such as water and a neutral salt (BX). During the titration, the strong base (B) will react with the strong acid (HX) to form water (H₂O) and a neutral salt (BX). The overall equation for the reaction is: HX + B → H₂O + BX

: Similarities between the two pH curves: 1) Both pH curves show the progress of a reaction as the base is added, resulting in an increase in pH. 2) The curves for both titrations have an initial rise and then level off at the buffer region (as acid and conjugate base concentrations come closer to equilibrium). 3) Both curves reach an equivalence point where the moles of acid and base are equal. Differences between the two pH curves: 1) The initial pH for the weak acid titration is higher than that of the strong acid titration, due to the different initial H₃O⁺ concentrations. 2) The buffer region's slope for the weak acid titration is more gradual compared to the strong acid titration. 3) The weak acid titration curve has a more gradual rise near the equivalence point compared to the sharp rise for the strong acid titration curve. 4) The equivalence point of the weak acid titration curve has a pH larger than 7 (due to the presence of a weak conjugate base), while the strong acid titration curve's equivalence point has a pH of 7.

: The similarities in both pH curves are due to the nature of acid-base titrations, where the base is added to react with the acid, resulting in an increase in pH as the H₃O⁺ concentration decreases. The differences in the pH curves are primarily due to the differing strengths of the acids being titrated: - A weak acid has a lower initial H₃O⁺ concentration, resulting in a higher starting pH. - The buffer region in the weak acid titration curve is more gradual due to the interactions between the weak acid and its conjugate base. - The weak acid titration curve has a more gradual rise near the equivalence point, as it requires more base to neutralize the weak acid completely. - The difference in equivalence point pH values is due to the presence of a weak conjugate base in the weak acid titration, while neutral species are found in the strong acid titration.