On the weak base/strong acid titration curve below, label the following points.
a) The point where the pH corresponds to a solution of the weak base (B) in water. b) The point where the pH corresponds to a solution of the conjugate acid (BH) in water.
c) The point where pH = pK, (for BH”).
The Correct Answer and Explanation is :
I currently don’t have the ability to access or view external links, but I can definitely help explain how to identify those points on a weak base/strong acid titration curve!
In a weak base/strong acid titration, the curve typically shows the relationship between the pH and the volume of acid added during the titration. Here’s a general way to identify the points you’re asking about:
a) The point where the pH corresponds to a solution of the weak base (B) in water:
This occurs before any acid is added. The pH at this point will be higher than 7, since weak bases produce hydroxide ions (OH⁻) in water. The solution is basic. Typically, the pH for a weak base in water will be above 8, depending on the strength of the base.
b) The point where the pH corresponds to a solution of the conjugate acid (BH) in water:
This happens after the weak base has been partially neutralized by the strong acid, but before reaching the equivalence point. The conjugate acid (BH) will hydrolyze in water, releasing H⁺ ions, making the solution acidic. The pH will be lower than 7, and the solution will behave more like a weak acid due to the presence of the conjugate acid. The pH will typically be in the range of 4–6, depending on the strength of the conjugate acid.
c) The point where pH = pKₐ for the conjugate acid (BH⁺):
This point occurs at the half-equivalence point during the titration, where half of the weak base has been neutralized to form the conjugate acid (BH⁺). At this stage, the concentration of the weak base (B) is equal to the concentration of its conjugate acid (BH⁺). The pH at this point equals the pKₐ of the conjugate acid, because this is the condition where the concentrations of the acid and its conjugate base are equal, leading to a pH equal to the pKₐ of the conjugate acid.
In summary, you can identify the different points by understanding the behavior of the weak base and its conjugate acid in water and observing how the pH changes as acid is added. The weak base starts at a higher pH, transitions to a lower pH as it is neutralized, and reaches a point where the pH equals the pKₐ of the conjugate acid.