Some Like It Hot, Some Like It Cold

In this Activity, students combine liquids in a calorimeter and use a thermometer to determine if the reaction mixture gets hot or cold. All of the chemicals (yeast, hydrogen peroxide, vinegar and baking soda) except ammonium nitrate, are available in supermarkets. The goal is to find a combination of a liquid and a solid that could serve as the basis for a cold pack of the type used for athletic injuries. This Activity focuses on heats of reaction and heats of solution. It can be used as an introduction to thermodynamics and calorimeters. It can also be extended to use quantitative data of heats of reactions, heats of solutions, and Hess’s law.