You wish to prepare a buffer containing CH₃COOH with a pH of 4.24. If the pK_a of acetic acid is 4.74, what ratio of [CH₃COO⁻]/[CH₃COOH] must you use? A) 0.10 B) 0.50 C) 0.32 D) 2.0 E) 2.8

Question

Quizplus · Accepted Answer

pH = pKa + log([A⁻]/[HA])

4.24 = 4.74 + log([A⁻]/[HA])

log([A⁻]/[HA]) = -0.5

[A⁻]/[HA] = antilog (-0.5)

[A⁻]/[HA] = 0.32

Therefore, the ratio of [CH3COO⁻]/[CH3COOH] to prepare the buffer with pH 4.24 is 0.32. Hence, the correct answer is C.

You Wish to Prepare a Buffer Containing CH3COOH with a PH

You Wish to Prepare a Buffer Containing CH₃COOH with a PH