Department of Chemistry, Davidson College

Titration of an Unknown Acid or Base

The applet below simulates the titration of an unknown acid or base.

To set-up the titration, the user must

Select one of the unknown compounds
Enter the mass of the unknown to be titrated
Enter the volume of water in which to dissolve the unknown
Select a titrant (0.1000 M NaOH or 0.1000 M HCl)

As soon as a valid mass and volume are provided, the pH of the solution will be shown. Once the titration is started (by adding titrant), the titration conditions cannot be altered.

Titrant may be added by selecting the "Add Titrant" button. The volume of titrant added may be chosen from the list below the button. As in a laboratory experiment, one must periodically record data in a laboratory notebook. By selecting the "Record Point" button, the current volume of titrant added and solution pH are entered in the electronic notebook at the right of the applet and the data point is plotted on the titration curve.

There are several restrictions in this titration:

No more than 50.00 mL of titrant may be added. (One is not allowed to refill the buret!)
No more than 100 data points may be recorded.

The possible unknown compounds are taken from the list of amino acids in the table shown below. You should be able to unambiguously identify the unknown compound and to determine the acid dissociation constant(s) from the titration data. (Each time the applet is loaded, the list of unknowns is scrambled.) When you think you have identified the unknown and determined the acid dissociation constant(s), select the "Show Unknown" button to check your conclusions.

Compound Name	Formula Weight	pK_a
Alanine Hydrochloride	125.556	2.34 9.69
Glycine Hydrochloride	111.53	2.350 9.778
Glutamic Acid, Disodium Salt	191.09	2.23 4.42 9.95
Leucine, Potassium Salt	169.27	2.329 9.747
Lysine Dihydrochloride	219.11	2.18 8.95 10.53
Phenylalanine Hydrochloride	210.65	2.20 9.31
Tyrosine Hydrochloride	217.65	2.20 9.11 10.07

Applet Name: titrate.Titrate.class
Archive: titrate.jar
Version: 0.1 (May 1998)

This applet is still under development; additional refinements will be forthcoming. Known problems and the revision history are listed at the bottom of this page. Please send feedback on performance and information on problems to David N. Blauch. This applet requires a Java-enabled browser that supports Java 1.1. Netscape Navigator 4.04 or later (with the JDK update for version 4.04) and Internet Explorer 4.1 provide such support.

Please let me know how you like this applet. If you encounter any bugs or errors, please provide me with the specific details. I would also appreciate any suggestions for improvements.

David N. Blauch; dablauch@davidson.edu

© Davidson College, August 1998 Error processing SSI file
Error processing SSI file
Last updated Wednesday October 16 2002