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. (c) Is the pH 7, less than 7, or more than 7 at the equivalence point?

Verified step by step guidance

1. insert step 1> Start by understanding that at the equivalence point in a titration, the amount of acid equals the amount of base. For a weak base titrated with a strong acid, the equivalence point is reached when all the weak base has reacted with the strong acid.
2. insert step 2> Recognize that the reaction between the weak base B and the strong acid HA will produce the conjugate acid of the weak base (BH^+) and water.
3. insert step 3> At the equivalence point, the solution contains the conjugate acid BH^+ and water. The conjugate acid can donate a proton to water, creating H_3O^+ ions, which makes the solution acidic.
4. insert step 4> Since the solution is acidic at the equivalence point due to the presence of BH^+, the pH will be less than 7.
5. insert step 5> Conclude that for a titration of a weak base with a strong acid, the pH at the equivalence point is less than 7.

Key Concepts

Weak Base and Strong Acid Titration

In a titration involving a weak base and a strong acid, the weak base does not fully dissociate in solution, leading to a less than neutral pH at the equivalence point. The strong acid completely dissociates, and the resulting solution will contain the conjugate acid of the weak base, which can further affect the pH.

Equivalence Point

The equivalence point in a titration is reached when the amount of titrant added is stoichiometrically equivalent to the amount of substance being titrated. For a weak base and strong acid, this point is characterized by the complete neutralization of the base, resulting in a solution that is typically acidic due to the presence of the conjugate acid.

pH of Solutions

pH is a measure of the hydrogen ion concentration in a solution, indicating its acidity or basicity. At the equivalence point of a weak base-strong acid titration, the pH will be less than 7 because the resulting solution contains the conjugate acid of the weak base, which contributes to an increase in hydrogen ion concentration.