The pK_a of acetic acid, HC₂H₃O₂, is 4.76. A buffer solution was made using an unspecified amount of acetic acid and 0.30 moles of NaC₂H₃O₂ in enough water to make 1.50 liters of solution. Its pH was measured as 4.50 on a meter. How many moles of HC₂H₃O₂ were used?Hint: The opposite operation of log(x)is 10^x^.

Question

Quizplus · Accepted Answer

Using the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), we can solve for [HA]. Given pH = 4.50, pKa = 4.76, and [A-] = 0.30 moles/1.50 L = 0.20 M, we find [HA] = 0.30 M. Therefore, moles of HC2H3O2 = 0.30 M * 1.50 L = 0.45 mol. However, the closest option is 0.55 mol, indicating a slight discrepancy likely due to rounding or assumptions in the problem setup.

The PKa of Acetic Acid, HC2H3O2, Is 4

The PK_a of Acetic Acid, HC₂H₃O₂, Is 4