Which of the following gives a buffer solution when equal volumes of the two solutions are mixed? (a) 0.10 M HF and 0.10 M NaF (b) 0.10 M HF and 0.10 M NaOH (c) 0.20 M HF and 0.10 M NaOH (d) 0.10 M HCl and 0.20 M NaF

Verified step by step guidance

1. Identify the components needed for a buffer solution: a weak acid and its conjugate base, or a weak base and its conjugate acid.
2. Analyze option (a): 0.10 M HF (a weak acid) and 0.10 M NaF (provides F⁻, the conjugate base of HF). This combination can form a buffer solution.
3. Analyze option (b): 0.10 M HF (a weak acid) and 0.10 M NaOH (a strong base). This will result in a neutralization reaction, not a buffer.
4. Analyze option (c): 0.20 M HF (a weak acid) and 0.10 M NaOH (a strong base). The NaOH will partially neutralize the HF, potentially forming a buffer if the weak acid remains in excess.
5. Analyze option (d): 0.10 M HCl (a strong acid) and 0.20 M NaF (provides F⁻). Since HCl is a strong acid, it will not form a buffer with NaF.

Key Concepts

Buffer Solutions

A buffer solution is a system that resists changes in pH upon the addition of small amounts of acid or base. It typically consists of a weak acid and its conjugate base or a weak base and its conjugate acid. This equilibrium allows the buffer to neutralize added acids or bases, maintaining a relatively stable pH.

Weak Acids and Conjugate Bases

Weak acids partially dissociate in solution, establishing an equilibrium between the undissociated acid and its ions. The conjugate base is formed when the weak acid donates a proton. In buffer solutions, the presence of both the weak acid and its conjugate base allows for effective pH stabilization.

pH and Neutralization Reactions

pH is a measure of the acidity or basicity of a solution, with lower values indicating higher acidity. Neutralization reactions occur when an acid reacts with a base, producing water and a salt. Understanding how these reactions affect pH is crucial for determining whether a mixture will form a buffer solution.