Assume that 30.0 mL of a 0.10 M solution of a weak base B that accepts one proton is titrated with a 0.10 M solution of the monoprotic strong acid HA. (b) What is the predominant form of B at the equivalence point?

Verified step by step guidance

1. Identify the chemical reaction: B (weak base) reacts with HA (strong acid) to form BH^+ (conjugate acid of B) and A^- (conjugate base of HA).
2. Determine the equivalence point: At the equivalence point, the moles of HA added are equal to the moles of B initially present.
3. Calculate the moles of B initially present: Use the formula \( \text{moles} = \text{concentration} \times \text{volume} \) to find the moles of B.
4. At the equivalence point, all B is converted to BH^+: Since B is a weak base and HA is a strong acid, the reaction goes to completion, converting all B to BH^+.
5. Conclude the predominant form: At the equivalence point, the predominant form of B is BH^+, the conjugate acid of the weak base B.

Key Concepts

Weak Base and Strong Acid Titration

In a titration involving a weak base and a strong acid, the weak base partially ionizes in solution, while the strong acid completely dissociates. At the equivalence point, the amount of acid added is stoichiometrically equivalent to the amount of base present, leading to the formation of the conjugate acid of the weak base.

Equivalence Point

The equivalence point in a titration is the stage at which the number of moles of acid equals the number of moles of base. At this point, the solution contains only the products of the neutralization reaction, which for a weak base and strong acid titration, results in the formation of the conjugate acid of the weak base.

Conjugate Acid

The conjugate acid is the species formed when a base accepts a proton. In this scenario, when the weak base B accepts a proton from the strong acid HA at the equivalence point, it transforms into its conjugate acid, which is the predominant form of B in the solution at that stage.