Two laboratory technicians prepare acetate buffer solutions at 25 °C
CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
Two laboratory technicians prepare acetate buffer solutions at 25 °C, each with a total acetate species concentration of 0.40 M. Technician I dissolves sodium acetate and acetic acid so that the solution contains 0.30 M CH₃COOH and 0.10 M CH₃COO⁻. Technician II prepares a solution containing 0.10 M CH₃COOH and 0.30 M CH₃COO⁻.
The pKₐ of acetic acid at 25 °C is 4.76.
(a) Describe qualitatively which technician’s buffer has the greater capacity for neutralizing an added strong base. Justify your answer in terms of chemical species present.
(b) Describe qualitatively which technician’s buffer has the greater capacity for neutralizing an added strong acid. Justify your answer in terms of chemical species present.
(c) Explain why the initial pH values of the two buffers are not equal, even though their total concentrations of acetate species are the same.