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 constantexpression (ECE) for all of the reactions thatoccur when NaOH is added to the acetic throughout the titration.Hint: think of what is in the solution (aceticacid) with water, acetic acid with sodium hydroxide, and acetateion with water) as the titration is proceeding.
2. Calculate the volume of NaOH solution needed to react theequivalence point.
3. The chart below has entries for several steps along thetitration curve (which shows the pH as a function of the volume ofNaOH solution added). To calculate the pH at each step, you mustfirst understand what species are present and which chemicalreactions are occurring, as that will dictate the method needed tocalculate the pH.
For each volume listed, fill in the table with the major species(one or more) present in the solution that could impact thesolution pH. Use stoichiometry! Based on what is present insolution, indicate whether Ka, Kb, the H-H (Henderson-Hasselbalch)equation, or the concentration of a strong acid or strong base inthe solution will be used to calculate [H3O+] and the solutionpH.
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, graphingpH vs volume of NaOH needed. Label the equivalence point, themidpoint (halfway point) of the titration, and the bufferregion.
