If an acetate buffer solution was prepared using method 1 and it was supposed to have a pH of 4.7 but it actually came out to 4.9, what could be done to adjust the pH back down to 4.7 without completely remaking the solution and without altering the total amount of conjugate particles (HA + A‐)?

Measure out 15.0 mL of 0.10 M HC2H3O2 and 15.0 mL of 0.10 M NaC2H3O2. Measure and record the pH of the individual solutions.

Combine the solutions together, mix well, and measure and record the pH of the resulting buffer solution.