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.
Flash rocks, typically pieces of quartz that produce light when struck together, are an example of the complex phenomenon of triboluminescence. The green chemistry aspects for the flash rock demonstration are considered, and LEGO models illustrating quartz crystals, piezoelectric materials, and nonpiezoelectric materials are presented.
Nora Walsh shares the outline of the interactive notebook pages she uses for her thermochemistry unit. All of the documents and foldables are available for download.
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.
The "Two-Faced" thionin reaction involves causing a purple solution to fade to colorless by shining light on the solution. I wondered if it could be demonstrated the color of light that caused this transition.
Did you know that sand can be converted into a mixture of gases that spontaneously ignites in air? The procedures involved are relatively simple to perform, spectacular to observe, and relate to a rich assortment of chemical principles.
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.
The blossoms of eastern skunk cabbage produce heat for a couple of weeks in early spring. This heat, which can be detected using an infrared camera, results from oxidation of carbohydrates. The mechanisms behind this process can be used to introduce energy transduction during classroom discussions of thermochemistry.
Learn how to thermochemically analyze the Devil's Milkshake chemical demonstration - just in time for Halloween!
Learn a simple way to relate the heat equation (Q = mc∆T ) to climate change.