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.
You can solve Chemical Mystery #20 if you know your chemistry...and your magic!
Student: "Why do I have to take this chemistry class?" Heard it before, perhaps numerous times right? Let's see what an astrophysicist has to say about this ubiquitous student question.
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.
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 familiar soda fountains that can be produced by adding Mentos candies to plastic bottles of carbonated beverages can also be produced by adding objects to carbonated beverages in aluminum cans. A variety of simple methods for producing soda fountains from cans are described.
The differing electrostatic and solubility properties of starch and polystyrene foam packing peanuts are used in various demonstrations to describe aspects of microplastics and their interactions with the environment. Their differing responses to exposure to liquid nitrogen and iodine solutions are also described.
It may come as no surprise that three of our very own lead contributors have been named as Finalists for the 2021 Presidential Awards for Excellence in Mathematics and Science Teaching (PAEMST) at the secondary level in their states. We would like to recognize them along with all of the amazing math and science teachers across the country that have earned this honor.
Stacks of LEGO bricks can be used to illustrate the composition and pressures of various planetary atmospheres. Guides for the construction and use of these atmosphere sticks are provided.