Susan E. Kegley and Joy Andrews
The purity of our water supplies is a pressing problem and will become increasingly more so in the coming years. This laboratory module is designed as an introduction to factors affecting water quality and the methods used to assess water quality. The chemical concepts covered include acid-base chemistry, spectroscopy, principles of sampling and quality control, the electrochemical techniques of potentiometry and ion selective electrodes, ion chromatography, and atomic absorption spectrophotometry. The module is constructed to be transferrable to a variety of institutions, providing multiple techniques for the analysis of individual water quality parameters. Some techniques require only a buret and a few chemicals, while others utilize sophisticated state-of-the-art instrumentation. In an undergraduate setting, the module is best carried out over three to five weeks, with the final week of the module used to introduce students to a spreadsheet and graphing program for data analysis.
This module has been tested for seven semesters in a first semester general chemistry course at the University of California, Berkeley in special laboratory sections focusing on environmental chemistry, as well as in the 1000-student regular general chemistry laboratory. Student response to the module has been overwhelmingly positive, with many students commenting that the knowledge gained has had a significant impact on their awareness of issues related to water quality and their ability to analyze data scientifically (see The Chemical Educator, 1996, vol. 1).
This module would also work well in an upper level instrumental methods of analysis course. More advanced students will be able to delve deeper into the theory and practice of ion chromatography or atomic absorption spectrophotometry. The laboratory text provides background information on the chemistry of natural waters not readily found in a single source.
A detailed instructor's manual, complete with supplier information, stockroom prep lists, pre-lab lecture notes, instrument parameters, and transparency masters, is available to provide assistance in carrying out this experiment.
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