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Thermochemistry

Will a Watched Pot Ever Boil? A Simple, but Effective, Chemistry Lab: Constructing a Heating Curve of Water

GraceAnne Lourie | Fri, 10/28/2022 - 13:07

This lab guides students through taking data and constructing their own heating curve for water. It requires no special equipment, is low prep, is safe, and can even be done at home for homeschool or distance learning. Even though the lab activity itself is relatively simple and straightforward, the concepts still engage students in higher level thinking and gives them important practice with laboratory techniques and forming hypotheses.

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. 

Too Hot to Handle? Hydrogen Reacts with Oxygen on Palladium Foil

Dean Campbell | Thu, 04/28/2022 - 20:50

The reaction of hydrogen and oxygen gases to form water is well known to be an exothermic reaction. That reaction can occur by first absorbing the hydrogen into palladium metal, and then placing the resulting palladium hydride into contact with oxygen in the air. Infrared and visible light videos were recorded for this process involving palladium foil, and the Green Chemistry and safety aspects of these activities are considered.

Thermal Paper as a Polarity and Acidity Detector

Dean Campbell | Thu, 10/28/2021 - 14:09

Thermal paper such as that used for point of sale receipts typically functions by darkening when exposed to heat. The pigment system used in this paper also darkens when exposed to solvents of intermediate polarity and acids. This enables thermal paper to be used as an inexpensive sort of indicator paper for a variety of demonstrations.