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 *0 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

The pH of a buffer is determined by the pKa of its conjugate acid-base pair. Ideally, the pKa of the acid should be within 1 pH unit of the desired pH of the buffer. The pKa of CH3COOH (acetic acid) is 4.76, which is within 1 pH unit of 4.5. Therefore, CH3COOH can be used to prepare a buffer with a pH of 4.5.

Which of the Following Acids Should Be Used to Prepare