How to Make a Coffee-cup Calorimeter

By Joseph Nicholson

The Latin word "calor," meaning heat, is the root of "calorie" and "calorimeter." A calorie is the amount of heat necessary to raise 1 kilogram of water by 1 degree Centigrade (about 4.2 kJ). A calorimeter is a device used to measure the heat energy released or absorbed in a chemical reaction. A coffee-cup calorimeter is a type of reaction calorimeter that uses a closed, insulated container for making heat measurements. Coffee cups, especially those made of Styrofoam, are effective calorimeters because they hold in the heat of the reaction.

Make the cardboard lid. Cut or separate a piece of cardboard large enough to completely cover the mouth of the Styrofoam cup. The lid should be flat and make a good seal when place on top of the cup.

Insert the thermometer. Poke a hole in the center of the cardboard lid large enough to fit the laboratory thermometer. The fit should be snug, though, so no heat will escape through the hole. Insert the thermometer far enough through the lid so the sensitive end will reach near the bottom of the coffee cup and the temperature can be read from the opposite end.

Insert the stirring rod. To keep the chemical reaction going, it might be necessary to stir the combination in the coffee cup. Thus, a small hole for a stirring rod should be poked through the lid to one side of the thermometer. Insert the stirring rod and be sure it fits snugly but has enough range of motion to stir.

Complete the assembly of the coffee cup calorimeter by placing the cardboard lid on the coffee cup. It will probably be necessary to use a clamp or a ring stand to hold the thermometer in place so it does not tip over the coffee cup.

About the Author

Joseph Nicholson is an independent analyst whose publishing achievements include a cover feature for "Futures Magazine" and a recurring column in the monthly newsletter of a private mint. He received a Bachelor of Arts in English from the University of Florida and is currently attending law school in San Francisco.