Which pair of chemical species forms an effective buffer solution when mixed in equimolar amounts?
Answer and explanation
Correct answer: D. CH₃COOH and CH₃COONa
- Step 1: Define a buffer solution: a mixture containing a weak acid and its conjugate base (or a weak base and its conjugate acid).
- Step 2: Acetic acid (CH₃COOH) is a weak acid and sodium acetate (CH₃COONa) provides its conjugate base (CH₃COO⁻). This pair buffers against pH changes.
Answer
CH₃COOH and CH₃COONa.
Why not the others: HCl, NaOH, and HNO₃ are strong acids/bases and cannot form functional buffer systems with neutral salts.
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