Question

Select the single best answer What is the purpose of an acid-base buffer? OA. To maintain both relatively constant pH and pK, in a solution. OB. To maintain a relatively constant pH in a solution. C. None of these. D. To maintain a relatively constant pK, in a solution.

Answer 1

Answer: Option (B) is the correct answer.

Explanation:

An aqueous solution that consists of a mixture of weak base and its conjugate acid or a weak acid and its conjugate base is known as a buffer.

When we add a strong acid or base into this mixture then the change in pH of this mixture is very small.

In a buffer solution, pH depends on the ratio of concentration of base divided by concentration of acid.  

It is known that for a given temperature, the value of $pK_{a}$ remains constant.

Therefore, relation between pH and $pK_{a}$ will be as follows.

                    pH = $pK_{a} + (log \frac{base}{acid})$

Thus, we can conclude that the purpose of an acid-base buffer is to maintain a relatively constant pH in a solution.