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.
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.
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.
The classic classroom or lab activity using coin flips to illustrate the first order kinetics of radioactive decay is connected to the tragedy of radiation exposure of workers at facilities using radium-containing luminescent paint. Some of the chemistry related to the contamination of these “radium girls” is explored, with connections being made to the Principles of Green Chemistry and the United Nations Sustainable Development Goals.
Thin sheets of polystyrene can be patterned with permanent markers to represent repeating units of the polymer and then shrunk down in size using heat. The shrunken models of the repeating units can be connected with a string and then flipped into positions to demonstrate different types of polymer tacticity.
Atomic theory is a common topic throughout any introductory chemistry course. It is likely that Rutherford’s gold foil experiment gets at least some attention in your course. This simple activity gives students an opportunity to replicate Rutherford’s experiment through an analogy experiment that may allow for easier conceptualization of the experiment itself and provide additional support for model development.
Addition of a small amount of azobenzene to eicosane can lower its melting point to where it can be melted by body heat. This can be used in demonstrations and classroom activities related to freezing point depression and phase diagrams.
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.