What is the hydrogen-ion concentration of a solution that is 0.052 M in acetic acid and 0.052 M in sodium acetate at 25°C? The acid-ionization constant of acetic acid is 1.8 × 10^-5 at 25°C. A)1.8 × 10^-3 M B)1.8 × 10^-6 M C)1.8 × 10^-7 M D)1.8 × 10^-5 M E)1.8 × 10^-4 M

Question

Quizplus · Accepted Answer

The solution is a buffer, and the hydrogen-ion concentration can be calculated using the Henderson-Hasselbalch equation. Since the concentrations of acetic acid and sodium acetate are equal, the pH is equal to the pKa, which is -log(1.8 × 10^-5) = 4.74. Therefore, the hydrogen-ion concentration is 10^-4.74 ≈ 1.8 × 10^-5 M.

What Is the Hydrogen-Ion Concentration of a Solution That Is