Which of the following acids should be used to prepare a buffer with a pH of 4.5? A) HOC₆H₄OCOOH, K_a = 1.0 × 10^-3 B) C₆H₄(COOH)₂, K_a = 2.9 × 10^-4 C) CH₃COOH, K_a = 1.8 × 10^-5 D) C₅H₅O₅COOH, K_a = 4.0 × 10^-6 E) HBrO, K_a = 2.3 × 10^-9

Question

Quizplus · Accepted Answer

To prepare a buffer with a pH of 4.5, we need an acid with a pKa value close to 4.5. The acid with the closest pKa value is CH3COOH (acetic acid), which has a pKa of 4.76. However, acetic acid is not among the options given. Among the given options, the acid with the closest pKa to 4.5 is CHO2COOH (lactic acid), which has a pKa of 3.86. Therefore, option C, which represents lactic acid, is the best choice for preparing a buffer with a pH of 4.5.

Which of the Following Acids Should Be Used to Prepare