Question

In an experiment, acid was added to two solutions:

Solution 1: distilled water only

Solution 2: distilled water containing sodium bicarbonate

Then, the pH of each solution was taken.

Solution 1 had a final pH of 4.5, while Solution 2 had a final pH of 6.8.

Which of the following statements explains the difference between the two solutions?

Choose 1 answer:

(Choice A)

The water in Solution 1 had a lower starting pH than the water in Solution 2.

(Choice B)

Hormones released in Solution 2 allowed it to maintain a higher pH.

(Choice C)

Sodium bicarbonate acted as a pH buffer in Solution 2.

(Choice D)

Sodium bicarbonate increases the temperature of a solution, which helped raise the pH of Solution 2.

Answer 1

Choice C. Sodium bicarbonate acted as a pH buffer in Solution 2.

Explanation:

Sodium carbonate is used as pH buffering agent. Buffering agent is a type of solution which contains weak base or acid which stabilize the solution when another strong acid or base is added to the solution. If acid is added, the weak base that is present in the solution reacts with it and when base is added, weak acid reacts with it.