A 100.0 mL solution contains 0.25 M benzoic acid and 0.25 M sodium benzoate
CHEMISTRY · Multi-part · AP · Chemistry · Acids and Bases · Acids and Bases
Problem
A 100.0 mL solution contains 0.25 M benzoic acid and 0.25 M sodium benzoate. A chemist adds 5.0 mL of 1.00 M HCl(aq) to the mixture. Assume the volume change is negligible.
(a) Calculate the initial pH of the benzoic acid/benzoate buffer before any HCl is added. The pKa of benzoic acid is 4.20.
(b) Determine the pH of the solution after the 5.0 mL portion of HCl is added, showing all stoichiometric and equilibrium steps.
(c) Decide whether the buffer has been significantly compromised by this addition. Support your answer with quantitative evidence from your calculations.