Oxygene...

For those of us who are a little "long in the tooth", you may remember Jean Michel Jarre and his synthesiser music from the 80s. Oxygene was one of those albums. Although oxygen was first discovered by Scheele in 1773, its discovery is usually attributed to Priestley who was first to publish his work in 1774. 

The classical test for oxygen in the chemistry lab is to apply a glowing splint (a half-lit match) to a tube containing the gas. I came across a nice variation the other day and since it is such a long time since I last did this experiment, we video-taped it. A class of fourth year high school students from LSS Messedaglia, Verona, were investigating the kinetics of the KI catalysed decomposition of hydrogen peroxide in a variant of the "elephant toothpaste" experience, by measuring the height of the foam as a function of time. The foam traps the oxygen gas produced during the reaction which is a bit easier than fiddling around with gases in test-tubes or collecting them over water. 

Update: today I repeated the experience with a class of students from IIS Calabrese - Levi (San Pietro, succursale). This video demonstrates the oxygen test very clearly...

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Thanks to Marilena Righetti for suggesting this experiment in the first place.
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