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thermochemistry

Burning paper towels soaked in various metal nitrates

Tom Kuntzleman | Mon, 10/16/2023 - 13:04

Igniting paper towels that have been soaked in concentrated potassium nitrate and allowed to dry yields a flame reminiscent of that produced by guncotton. Repeating this experiment with other metal nitrates produces flames with different colors, plus a few other chemical surprises! This series of experiments is fascinating and connects to a wide variety of chemical topics including combustion, redox reactions, chemical thermodynamics, and flame tests. You don't want to miss this one!

Chemical Activities Involving Reversible Thermochromic Pigments

Dean Campbell | Wed, 08/16/2023 - 07:17

The color of a thermochromic system depends on its temperature. The colors of leuco dye-based systems can also be influenced by adding acids or bases to the thermochromic reactions. These can be used to create colorful demonstrations of acid-base chemistry. Thermochromism found in color changing cups can also be used to visualize heat flow, and therefore thermodynamic principles, associated with stretching and contracting elastomers.

Seashell Chemistry

Tom Kuntzleman | Thu, 06/01/2023 - 14:15

Placing dry ice in limewater is a great demonstration to accompany discussions on a variety of chemical topics, including the impact of ocean acidification on marine organisms that depend upon the formation of CaCO3.

Using My Marbles: Connecting Surface Area and Calorimetry with Temperature Curves and Thermochromic Cups

Dean Campbell | Sat, 07/30/2022 - 15:02

The importance of surface area can be illustrated by adding spherical solids at known sizes and temperature to other substances at different temperatures and then monitoring the rates of temperature changes of the system over time. Larger spheres (with less surface area per sample) exchanged heat with water more slowly than smaller spheres, and less thermally conductive glass spheres exchanged heat with water more slowly than iron spheres. Additional, more colorful demonstrations are described in which small glass spheres cool thermochromic plastic cups more quickly than larger glass spheres.