College Level Guided-Inquiry Lab Kit: Gravimetric Analysis of Calcium and Hard Water is an engaging activity where you investigate the concentration of calcium ions in hard water and consumer products using gravimetric analysis.
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College Level General Chemistry Guided-Inquiry Experiment
As water flows through rocks and soil, it picks up minerals from the Earth’s surface. Although many minerals are essential for life and health, high levels of calcium, magnesium, and iron ions in hard water may also be a nuisance. In this guided-inquiry lab, students investigate the concentration of calcium ions in hard water and consumer products using gravimetric analysis.The purpose of this advanced inquiry lab is to investigate the suitability of gravimetric analysis for determining the amount of water hardness in the form of calcium carbonate, CaCO3, in various water samples. Six samples, representing a wide range of potential water hardness from 50 ppm to 500 ppm, will be analyzed by various student groups as part of a cooperative class investigation to determine the accuracy and sensitivity of gravimetric analysis for water hardness testing. The lab begins with an introductory activity to develop skill in the calculations and techniques of gravimetric analysis, in particular, quantitative transfer and vacuum or gravity filtration. The procedure provides a model for guided-inquiry design of the cooperative class investigation described above. Antacid tablets are also provided as an opportunity for further inquiry—the use of gravimetric analysis to determine the amount of calcium in an over-the-counter medication.
Complete for 24 students working in pairs.