Question

Which of the following will make a basic buffer solution?

• A. 100 mL of 0.1 M CH₃COOH + 100 mL of 0.1 M NaOH
• B. 100 mL of 0.1 M HCl + 100 mL of 0.1 M NaOH
• C. 50 mL of 0.1 M KOH + 25 mL of 0.1 M CH₃COOH
• D. 100 mL of 0.1 M HCl + 200 mL of 0.1 M NH₄OH

Hint:

When creating a buffer solution, ensure the weak component (acid or base) and its conjugate (salt) are present in appropriate amounts to resist pH changes effectively.

Answer 1

The Correct Option is D

Analysis: - A basic buffer solution is created from a weak base and its salt with a strong acid.
- Option 1 creates a weakly basic or neutral buffer as acetate acts as a weak base after neutralizing the acid.
- Option 2 results in a neutral solution, not a buffer, as HCl and NaOH fully neutralize each other.
- Option 3 does not provide sufficient weak base and salt for proper buffering.
- Option 4, however, provides a weak base (NH₄OH) with an excess over the strong acid (HCl), allowing for buffer action through NH₄⁺ (from NH₄OH neutralizing HCl) and excess NH₃. Thus, it forms a basic buffer.