A 500 mL aqueous buffer contains 0.20 M acetic acid and 0.30 M sodium acetate at 25 °C
CHEMISTRY · Multi-part · AP · Chemistry · Acids and Bases · Acids and Bases
Problem
A 500 mL aqueous buffer contains 0.20 M acetic acid and 0.30 M sodium acetate at 25 °C. The pKa of acetic acid is 4.74. The buffer is subjected to two sequential additions of strong base:
• Step 1: 10.0 mL of 1.00 M NaOH is added.
• Step 2: An additional 20.0 mL of 1.00 M NaOH is added to the same solution from Step 1.
(a) Determine the pH of the original buffer before any NaOH is added.
(b) Calculate the pH after Step 1.
(c) Calculate the pH after Step 2.
(d) Based on your results, evaluate how close the buffer is to being overwhelmed after the second addition. Support your evaluation with numerical reasoning.