One beaker contains 10.0 mL of acetic acid/sodium acetate buffer at maximum buffer capacity (equal concentrations of acetic acid and sodium acetate), and another contains 10.0 mL of pure water. Calculate the hydronium ion concentration and the pH after the addition of 0.25 mL of 0.10 M HCl to each one. What accounts for the difference in the hydronium ion concentrations? Explain this based on equilibrium concepts; in other words, saying that "one solution is a buffer" is not sufficient.
Ka of acetic acid = 1.8 x 10^-5
Acetic acid/sodium acetate buffer
Acetic acid .1M
Sodium acetate .1M