Supercooled Water

Description:  Supercooling occurs when the temperature of a liquid is lowered below the freezing point without forming a solid. In the case of water it needs a seed crystal or a nucleation site to start forming ice. If the water has been filtered through reverse osmosis or chemical demineralization it can be safely cooled below the freezing point. Simply shaking the bottle forms solid ice.

Web Resource:  Supercooling - Wikpedia

simple demonstration of supercooled water and rapid nucleation.

Reaction in a Bag

Description:  This video shows a chemical reaction of sodium bicarbonate (baking soda), calcium chloride (road salt), and an indicator phenol red. The chemicals react to form calcium carbonate, sodium chloride, and carbon dioxide gas. This changes the pH inside the bag resulting in a color change in the phenol red. As much air as possible should be removed from the bag as possible to show the production of the gas. This could be used as an example of chemical reaction that releases energy (exothermic). Since the bag is sealed it could be massed before and after to show the conservation of mass (atoms). This phenomenon was submitted by Brian Babulic.

Web Resources:  Reaction in a Bag - Flinn Scientific, American Chemical Society - Explanation

This video show the chemical reaction between phenol red liquid, sodium bicarbonate (white powder), and calcium chloride (white bits). There is a chemical reaction that produces carbon dioxide gas which inflates the bag, heat, and color changes to yellow. ScienceFix.com producer: Darren Fix

Burning Steel Wool

Description:  This is an excellent phenomenon to discuss chemical reactions and the conservation of mass. Steel wool is burned leading to an increase in mass. When doing this in class show the students the burning steel wool to begin with and have them predict the change in mass. Most students believe the mass will either increase or decrease. This phenomenon can be used at the beginning of a unit on chemical reactions and students can investigate their individual models. (e.g. mass comes from fire, oxygen, carbon, etc.)

Web Resources:  Combustion of Iron Wool - CFNS Experiment 36

High School Chemistry Mass change during a chemical reaction Iron wool/steel wool is placed on an electric balance and ignited using a burning splint. The change in mass can be observed as the iron wool burns. Students should be able to explain why the mass reading on the balance increases at the end of the experiment.

A good experiment for youngsters.Ask first: Does iron burn? 'No' they say. Ask: When things burn do they get heavier or lighter? 'Lighter' they say. Use iron wool, not steel wool and get the finest grade you can get from the ironmongers.

Reusable Heat Packs

Description:  This phenomenon uses a supersaturated solution of sodium acetate. Clicking the metal disc releases a small number of crystals of sodium acetate which act as nucleation sites for the crystallization of the sodium acetate into a hydrated salt. Energy is released from the crystal lattice. The heating pack can be placed in boiling water and the sodium acetate can be dissolved again. This phenomenon shows how bond energy can be released.  It also shows the importance of chemical engineering and could lead to a section where students design a device (or application) of their own.

Web Resource:  Chemical Heat Pack - Wikipedia, Snappy Heat - Amazon

Clicking the metal disk inside causes a few of liquid sodium acetate molecules to flip to a crystallized state causing a chain reaction. The solidifying liquid creates 130°F of exothermic heat in the process. You can boil the package to return the crystallized sodium acetate back to a liquid form for reuse.

Ice Cube Spikes

Description:  Ice cube spikes form when the exterior of the ice cube freezes first and the expanding water from the inside is forced out through a small hole or weak spot in the exterior. The phenomenon can be used to show the reversible change of freezing in elementary or the intermolecular forces between molecules in high school chemistry.

Web Resource: Spikes on Ice Cubes

Uploaded by bloo777 on 2016-01-03.

Why do spikes form on ice cubes? Without them the world would be vastly different. Awesome Jingle by Accent: http://bit.ly/AccentVe Thanks to Prof. Stephen Morris from UofT: http://bit.ly/1GFANBE Filmed in part by Martin Marek in Olomouc, Czech Republic Time lapse of a growing ice spike by Lesley Hill, Russ Sampson and Edward Lozowski, with technical help by Kenny Lozowski.