Which of the following buffers will have the lowest pH? A) A solution containing 0.20 M HC₂H₃O₂ and 0.20 M NaC₂H₃O₂ will have the lowest pH. B) A solution containing 0.25 M HC₂H₃O₂ and 0.15 M NaC₂H₃O₂ will have the lowest pH. C) A solution containing 0.15 M HC₂H₃O₂ and 0.25 M NaC₂H₃O₂ will have the lowest pH. D) They all will have the same pH.

Question

Quizplus · Accepted Answer

The pH of a buffer solution is determined by the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), where [A-] is the concentration of the conjugate base and [HA] is the concentration of the acid. In option B, the ratio of conjugate base ([A-]) to acid ([HA]) is the lowest, which means the log([A-]/[HA]) term will be more negative compared to the other options, resulting in the lowest pH.

Which of the Following Buffers Will Have the Lowest PH