Question

Consider the titration of 25.0 mL of 0.100 M acetic acid (HA) with 0.100 M NaOH.

1. Write the balanced chemical equation and equilibrium constant expression (ECE) for all of the reactions that occur when NaOH is added to the acetic throughout the titration. Hint: think of what is in the solution (acetic acid) with water, acetic acid with sodium hydroxide, and acetate ion with water) as the titration is proceeding.

2. Calculate the volume of NaOH solution needed to react the equivalence point.

3. The chart below has entries for several steps along the titration curve (which shows the pH as a function of the volume of NaOH solution added). To calculate the pH at each step, you must first understand what species are present and which chemical reactions are occurring, as that will dictate the method needed to calculate the pH.

For each volume listed, fill in the table with the major species (one or more) present in the solution that could impact the solution pH. Use stoichiometry! Based on what is present in solution, indicate whether Ka, Kb, the H-H (Henderson-Hasselbalch) equation, or the concentration of a strong acid or strong base in the solution will be used to calculate [H3O+] and the solution pH.

Complete the calculations.

Volume NaOH added (mL)	Major Species	Equation	[H3O+]	pH
0.00
5.00
12.50
20.00
25.00
30.00

4. Sketch the titration curve that would be obtained, graphing pH vs volume of NaOH needed. Label the equivalence point, the midpoint (halfway point) of the titration, and the buffer region.

Answer 1