Question

Which of the following combinations would not result in the formation of a buffer solution?

• A. \( \text{NH}_3 + \text{HCl} \)
• B. \( \text{NH}_4 \text{Cl} + \text{NH}_3 \)
• C. \( \text{CH}_3 \text{COOH} + \text{NaOH} \)
• D. \( \text{NaOH} + \text{CH}_3 \text{COOH} \)

Hint:

A buffer solution requires a weak acid and its conjugate base or a weak base and its conjugate acid.

Answer 1

The Correct Option is D

Step 1: Buffer solution definition.
A buffer solution contains a weak acid and its conjugate base or a weak base and its conjugate acid.

Step 2: Identify buffer solutions.
- (1) \( \text{NH}_3 + \text{HCl} \): This combination forms an acidic buffer.
- (2) \( \text{NH}_4 \text{Cl} + \text{NH}_3 \): This is a buffer solution.
- (3) \( \text{CH}_3 \text{COOH} + \text{NaOH} \): This forms a buffer solution as it creates the conjugate base of acetic acid.
- (4) \( \text{NaOH} + \text{CH}_3 \text{COOH} \): This does not form a buffer as it is a strong base reacting with a weak acid.
Thus, the correct answer is (4).