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Surprising Shrinking Styrofoam Stick: Using the Gas Laws to Get a Square Peg into a Round Hole

Dean Campbell | Thu, 11/10/2022 - 16:45

Polystyrene foam sticks with a square or rectangular profile will not fit into a round target hole (e.g., the opening of a soda bottle) at room temperature. However, they do contract sufficiently in contact with liquid nitrogen to fit into the hole and produce a simple demonstration of Charles’s Law. Many other polymer foams do not shrink under these conditions, but still provide opportunities to discuss and explore their structure and chemistry.

Expanding on Self-Inflating Balloons: Activities Involving Moles, Gas Laws, and Thermochemistry

Dean Campbell | Thu, 02/10/2022 - 08:42

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.

Soda Fountains from Aluminum Cans

Dean Campbell | Thu, 09/16/2021 - 15:18

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.

Real vs Ideal - Do Students "Get It"?

Ben Meacham | Sat, 05/22/2021 - 23:49

Allowing students to confront the failure of a model and then helping them construct a new or slightly modified model to account for new observations is at the heart of the process of science. Ben Meacham shares one approach that can be deployed with a variation of depth, making it attainable for anyone learning about chemistry.

The Carbon Dioxide Spiral Staircase

Douglas Mulford | Mon, 03/15/2021 - 11:17

The demonstration where CO2 is generated and used to snuff out a candle in an aquarium or other container is well known. This article describes a dramatic variation on these demonstrations that allows for discussion of such topics as the ideal gas law, densities of different gases, gas density changes with temperature, miscibility, and viscosity. The device described is easily and inexpensively produced and stored. The demonstration is large scale and works well for classrooms and community outreach events.