# Plotting a titration curve for Ala and His

Here is the problem:

1. Assume you have a solution containing 0.1 mol of Ala adjusted to pH = 0.5 with HCl. You begin adding 1.0 M NaOH. Plot (do not sketch) the resulting titration curve (pH vs. moles NaOH added) showing all inflection points. Show your calculations and be sure to state your assumptions.

2. Plot a similar titration curve for a solution containing 0.1 mol of His at pH = 0.5. (pKa values: Ala: alpha-COOH = 2.3, alpha-NH2 = 9.7; His: alpha-COOH = 1.8, alpha-NH2 = 9.2, Imidazole = 6.0).

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#### Solution Preview

Please see attached document/graph/spreadsheet for your solution.

The OTAs on this web site are obliged not to create solutions for students that could be printed off and handed in if it were an assignment. Rather we are to provide highly instructional information that can aid in understanding of the question posed. I hope I can be of the kind of assistance you seem to be looking for, but I am glad you increased the number of units bid on this question and provided some further instructions for what you were after. A question like this could take anywhere from two to three (maybe even four) hours, to make sure we are certain we have the formulas correct, create a written response, do all calculations, check our work, etc. For 3 credits we get about $10, which at $5-$3/hr, is fair and acceptable to many Tas, but does not really reflect the time required or quality of the work. You seem to want a pretty comprehensive (daunting) treatment of the topic, for which a TA will require more time than usual.

Anyway, here goes. I've been trying to work on this response for awhile but the website has had some technical difficulties lately... my apologies. Your task is to explore the acid-base properties of ...

#### Solution Summary

This solution includes plots of titration curves, including calculations.