You wish to prepare an HC₂H₃O₂ buffer with a pH of 4.14.If the pK_a of is 4.74,what ratio of C₂H₃O₂⁻/HC₂H₃O₂ must you use? A) 0.10 B) 0.60 C) 0.25 D) 3.98 E) 4.0

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Quizplus · Accepted Answer

To calculate the ratio of [C₂⁻]/[HC₂H₃O₂], we can use the Henderson-Hasselbalch equation: pH = pK_a + log([C₂⁻]/[HC₂H₃O₂]) 4.14 = 4.74 + log([C₂⁻]/[HC₂H₃O₂]) -0.60 = log([C₂⁻]/[HC₂H₃O₂]) We can then take the anti-log of both sides to eliminate the log term: 0.25 = [C₂⁻]/[HC₂H₃O₂] Therefore, the ratio of [C₂⁻]/[HC₂H₃O₂] that should be used is 0.25, or 1:4.

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