Is fire a solid, a liquid, or a gas? – TED Ed by Elizabeth Cox

Sitting around a campfire, you can feel its heat, smell the woody smoke, and hear it crackle. If you get too close, it burns your eyes and stings your nostrils. You could stare at the bright flames forever as they twist and flicker in endless incarnations… But what exactly are you looking at? Elizabeth Cox illuminates the science behind fire. Continue reading

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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