A 25.0 mL sample of 0.150 M propionic acid, C₂H₅COOH (Ka = 1.3 × 10⁻⁵)
CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A 25.0 mL sample of 0.150 M propionic acid, C₂H₅COOH (Ka = 1.3 × 10⁻⁵), is titrated at 25 °C with 0.150 M NaOH. Exactly 12.0 mL of NaOH have been added, and the titration is still in the buffer region (before the half-equivalence point).
(a) Calculate the number of millimoles of propionic acid and of its conjugate base present in the reaction mixture after the 12.0 mL addition. Show all work.
(b) Determine the pH of the solution at this stage of the titration. Report your answer to two decimal places and show your reasoning.