Which of the Following Pairs Would Be the Best Buffer

Question

Which of the following pairs would be the best buffer at pH 10.0?
A) Acetic acid and sodium acetate (pKa= 4.76)
B) H2CO3and NaHCO3(pKavalues are 3.77 and 10.4)
C) Lactic acid and sodium lactate (pKa= 3.86)
D) NaH2PO4and Na2HPO4(pKavalues are 2.1, 7.2, 12.4)
E) Sodium succinate and succinic acid (pKa= 4.21)

Accepted Answer

A buffer solution is most effective at a pH equal to its pKa. In this case, option B has a pKa of 3.77 and 10.4, which is closest to pH 10.0. Therefore, option B is the best buffer for pH 10.0.