The pK_a of acetic acid (HC₂H₃O₂) is 4.75. What is the pH of a buffer in which [HC₂H₃O₂] = 0.20 M and [NaC₂H₃O₂] = 2.0 M? A) 3.75 B) 4.75 C) 5.75 D) 7.00

Question

Quizplus · Accepted Answer

First, we need to calculate the pKa of acetic acid: pK_a = -log(Ka) 4.75 = -log(Ka) Ka = 1.8 x 10^-5 Next, we use the Henderson-Hasselbalch equation to calculate the pH of the buffer: pH = pKa + log ([A-]/[HA]) pH = 4.75 + log (0.20/2.0) pH = 4.75 - 0.70 pH = 5.05 Therefore, the pH of the buffer is 5.05, which is closest to choice C (5.75).

The PKa of Acetic Acid (HC2H3O2) Is 4

The PK_a of Acetic Acid (HC₂H₃O₂) Is 4