P620: Contextual and active learning in the introductory analytical course: The water module
Extending the 1995 NSF Systematic Change Initiative in Chemistry beyond the general chemistry course, Grinnell College has used a module about the ionic composition of drinking water in its introductory analytical course for many years. Here we contextualize applications of chemical analysis and link the measured concentrations of cations and anions in various water samples to the geological source, local environment, and human treatment/regulation of water. “What’s in your Water besides H2O?” is a four week, 5 laboratory module. The class and lab sessions place solubility equilibria side by side with chemical analyses for bicarbonate, calcium and magnesium, then water softening processes coupled to sodium analysis by atomic emission spectroscopy and analyses of chloride, nitrate, and fluoride with electrochemical analytical methods (potentiometric titration and ion selective electrodes). Finally, anion chromatography is used to determine the sulfate ion concentrations in water and apply a chromatographic analytical technique to a real sample. The Water Module culminates in student presentations which report the analytical results on 8 ions and contrast the concentrations found for the various water samples with the origins, treatments, and community reported results.