DETERMINATION OF CARBONATE CONTENT IN ROCKS BY TITRATION: A LABORATORY EXERCISE FOR GEOCHEMISTRY AND SOIL SCIENCE COURSES

The traditional method of carbonate determination in geochemistry and soil chemistry courses has been using a calcimeter. Because calcimeters are not available in many student laboratories, we developed a simple titration method using hydrochloric acid and sodium hydroxide. The carbonate content of eight rock samples from the Leland Natural Bridge Formation in Sauk County, Wisconsin was determined using both the traditional calcimeter method and our new method and were statistically compared. After validating the titration method, it was integrated into a sample laboratory designed for an upper-level undergraduate geochemistry course. Our exercise integrates several important scientific skills, including the use of basic chemistry laboratory equipment, construction of calibration lines, determining statistical error, and basic chemical stoichiometry. The proposed laboratory questions efficiently develop the quantitative thinking ability essential in a scientist.