Alka-Seltzer® Rainbow – submitted by Flinn Scientific Canada

The Alka-Seltzer tablets contain sodium bicarbonate and citric acid. As the Alka-Seltzer tablet dissolves in water, the citric acid
reacts with the sodium bicarbonate to produce carbonic acid (Equation 1) and carbon dioxide (Equation 2). The carbonic acid
then reacts with the basic sodium hydroxide to change the pH of the solution (Equations 3 and 4). As the base is consumed, the
solution will slowly become more acidic, resulting in the colour changes.

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Carbon Dioxide Solubility Demonstration – submitted by Flinn Scientific Canada

A candle and beaker of pink phenolphthalein solution are placed inside a jar. The candle is lit and the jar is capped. The flame expectedly goes out as the oxygen is depleted. After the flame is extinguished, the pink solution slowly fades to colourless. What has happened inside the jar?

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LeChâtelier’s Principle and the Solubility of Carbon Dioxide

This activity demonstrates the effect of pressure and temperature on three reversible reactions: the solubility of carbon dioxide in water, the reaction of dissolved carbon dioxide and water to form H2CO3, and the weak acid ionization of H2CO3 to give HCO3- and H+ ions. For simplicity sake in terms of classroom discussion, these reactions are combined into one equation in Equation 1. Continue reading

pH Rainbow Tube


In this demo, the teacher creates a beautiful rainbow of colours in a demonstration tube using universal indicator and a dilute
acid and base.


Universal indicator can be used to illustrate an entire range of pH conditions because it is made up of a mixture of different
indicators that change colour at different pH values. As an acid is diluted with water, its pH increases—but never above pH 7.
Likewise, as a base is diluted, its pH decreases—but, again, never below pH 7. Continue reading

“Cook” an Egg with No Heat!? (Egg-cellent Weird Science Experiments)

Everyone loves the incredible edible egg, but what about a green one? Today we’re coming at you with three kitchen egg demos that will bounce, denature, and colorize you into total chemical bewilderment! Continue reading