Question

If a small amount of a strong base is added to buffer made up of a weak acid, HA, and the sodium salt of its conjugate base, NaA, the pH of the buffer solution does not change appreciably because:__________

a. the K, of HA is changed.
b. No reaction occurs.
c. the strong base reacts with A to give HA, which is a weak acid.
d. the strong base reacts with HA to give AOH and H'.
e. the strong base reacts with HA to give A, which is a weak base,

Answer 1

e. the strong base reacts with HA to give A, which is a weak base

Step-by-step explanation:

Let's consider a buffer made up of a weak acid, HA, and the sodium salt of its conjugate base, NaA. The function is a buffer system is to muffle the change in the pH when an acid or a base is added.

Let's suppose a strong base is added. Then, OH⁻ would be more available. OH⁻ ions react with the acid component of the buffer and its effect is reduced. The corresponding reaction is:

OH⁻ + HA ⇄ A⁻ + H₂O

As we can see, the strong base reacts with HA to give A, which is a weak base.