Question

Select the statements that correctly describe a buffer.

1) The pH of a buffer solution does not change significantly when any amount of a strong acid is added.
2) A buffer is generally made up of a weak acid and its conjugate base.
3) An acid added to the buffer solution reacts with the weak base of the buffer.
4) The pH of a buffer solution is determined by the ratio of the concentration of conjugate base to the concentration of strong acid.
5) The Ka of a buffer does not change when any amount of an acid is added to the buffer solution.

Answer 1

3) An acid added to the buffer solution reacts with the weak base of the buffer.

Step-by-step explanation:

1) is wrong. A buffer can accept a strong acid up to its buffer capacity. After that, it is no longer an effective buffer.

2) is wrong. A buffer can consist of a weak acid and its conjugate base, but it can just as often consist of a weak base and its conjugate acid (your teacher may say that this option is correct).

4) is wrong. The ratio of the concentration of conjugate base to the concentration of weak acid determines the pH of the buffer.

5) is wrong. The Kₐ is a property of the weak acid or base and not of the buffer.