Heats of Reaction and Hess's Law - Small-Scale Calorimetry Laboratory Kit

By: The Flinn Staff


An intense flame, blinding light, and searing heat—magnesium burning in air is a dazzling reaction. But how much heat is produced when magnesium burns?

In this advanced-level microscale experiment, students use an indirect method and Hess's Law to determine the heat of reaction for the combustion of magnesium. Students measure the heats of reaction for magnesium and magnesium oxide reacting with hydrochloric acid in special small-scale calorimeters. Using Hess's Law and a little algebra, students then combine these measurements with the heat of formation of water to determine the heat of reaction for the overall reaction, magnesium burning in air! This is a perfect experiment for students who have completed an introductory calorimetry experiment and want a little challenge. Special small-scale calorimeters included with the kit give remarkably accurate results.

Includes reproducible student handouts, detailed background information, complete Teacher Notes with sample data and answers to questions, and the chemicals and small-scale calorimeters needed to perform the lab.

Complete for 30 students working in pairs. Digital thermometers are recommended and available separately.