Which of the following pairs would be the best buffer at pH 10.0? A)acetic acid and sodium acetate (pK_a= 4.76) B)H₂CO3 and NaHCO₃ (pKas are 3.77 and 10.4) C)lactic acid and sodium lactate (pK_a = 3.86) D)NaH₂PO4 and Na2HPO4 (pK_as are 2.1,7.2,12.4)

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Quizplus · Accepted Answer

A buffer system works best when the pKa of the weak acid is within ±1 pH unit of the desired pH of the buffer. The pKa of H2CO3 is 3.77, and the pKa of NaHCO3 is 10.4. Since the desired pH is 10.0, the buffer system consisting of H2CO3 and NaHCO3 is the best choice as the pKa of NaHCO3 is close to the desired pH. The other options have pKa values too far from pH 10.0.

Which of the Following Pairs Would Be the Best Buffer