Which of the Following Combinations Would Be Best to Buffer

question 22

Multiple Choice

Which of the following combinations would be best to buffer an aqueous solution at a pH of 9.24?

• A) H₃PO₄ and H₂PO₄^-,K_a1 = 7.5 × 10^-3
• B) HNO₂ and NO₂^-,K_a = 4.5 × 10^-4
• C) CH₃CO₂H and CH₃COO^-,K_a = 1.8 × 10^-5
• D) H₂PO₄^- and HPO₄^2-,K_a2 = 6.2 × 10^-8
• E) NH₄⁺ and NH₃,K_a = 5.7 × 10^-10