Calculate the number of moles of sodium acetate (CH₃COONa) that must be added to 1.00 L of 0.100 M CH₃COOH ( K _a = 1.8×10^{- 5}) to give a buffer with pH₅.00.

Question

Quizplus · Accepted Answer

To create a buffer with a pH of 5.00 using acetic acid (CH3COOH) and sodium acetate (CH3COONa), we use the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), where [A-] is the concentration of the acetate ion and [HA] is the concentration of acetic acid. Given that the pKa = -log(1.8×10^-5) = 4.74, and the desired pH is 5.00, we can set up the equation as 5.00 = 4.74 + log([A-]/[0.100]). Solving for [A-] gives [A-] = 0.100 * 10^(5.00-4.74) = 0.100 * 10^0.26 ≈ 0.18 M. Therefore, to achieve a pH of 5.00, 0.18 moles of sodium acetate must be added to 1.00 L of the solution.

Calculate the Number of Moles of Sodium Acetate (CH3COONa) That

Calculate the Number of Moles of Sodium Acetate (CH₃COONa) That