Flash rocks were discussed in a previous post as stones made of quartz that produce light by triboluminescence when struck together. This post provides some description of their origins and tips on how to find them, making connections to some of their properties.
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.
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.
Flat, symmetrical molecules can be modeled by folding a sheet of paper, cutting patterns into the folded structure, and unfolding to produce the flat paper models. The finished models resemble paper snowflakes, but have a variety of rotational symmetries. Template patterns for several molecules are available for download in the Supporting Information.
For your enjoyment, we present lists of chemically-related words that end in the letters “-cation” but do not actually refer to the positively-charged chemical species. The lists are available for download in the Supporting Information.
Balloons that inflate using carbon dioxide produced from the reaction of citric acid and sodium hydrogen carbonate can be used to demonstrate a number of aspects of chemistry. Gas laws were used with the balloons to illustrate limiting reactants, molar mass of gases, and rockets. The endothermic reaction in the balloon was visualized with an infrared camera, and the Green Chemistry aspects of these balloons were considered.
This blog post includes short descriptions of demonstrations and props that Dean Campbell has used while teaching his collegiate General Chemistry I course.
