Be sure to coat your burette with the standardized 0.10 M NaOH solution and rinse before filling. Don’t bother trying to start at exactly the 0.00 ml mark on the burette. Once you’ve filled the burette with NaOH solution and cleared bubbles from the tip, you should not have to do this again; just refill the burette after each titration and don’t let the burette get emptied. You shouldn’t use a titration that consumes more than 50 ml of titrant.

Spread the three acid bottles out on an unused bench top. Get a 25 ml pipette and a 5 ml pipette for each acid bottle. DON’T MIX THE PIPETTES! If you have forgotten how to use a pipette bulb, practice on water first before you pipette acid solution in to the Erlenmeyer flask. Use a 250 ml Erlenmeyer flask for the titrations, or if you have permission from the instructor, you can use a beaker and a magnetic stirrer.

Do a quick and dirty titration of 5 ml of acid to check roughly for each end point. That way you can do the big titrations faster, and you’ll know were the buffering region is. You can always add more DI water to the titration if the volume is too small for the pH meter. Remember to add 2 drops of phenolphthalein to each titration before you start.

During the big titrations, while passing through the buffering region (where pH = pKa) and also while passing through the endpoint, add 0.20 ml of titrant at a time and read the pH after each addition of titrant. You want readings close together in these regions so that you can make an accurate graph in these regions. In other parts of the titration your readings can be 2 ml apart. If you wish, add phenolphthalein as a check on your endpoint.

Graph the data as you get it! You may plot several titrations on one sheet.

Compare the shape of the titration curve to the curves in Harris’s textbook.

Repeat a titration if the curve doesn’t make sense.

Compute the molarity of the acetic acid solution and write it on the board. Compare the results among groups; if one group gets a molarity for acetic acid very different from everyone else’s, then that group should check their calculations and repeat the titration. Compute the molarity of the X and Y solutions and write them on the board; again, check to make should all groups get consistent results. NOTE the concentrations of solutions X and Y that are written on the bottle; the units are grams of acid per Liter of solution.  Working with your partner, compute the molecular weight of X and Y using the given concentrations. X and Y are both monoprotic acids listed in Appendix G of Harris’s textbook. Use the molecular weight and the pKa to determine identity of the unknown acids.