Slow motion combustion experiments.

Wanting to illustrate combustion for GCSE chemistry using a classic demo with a new twist, I did a Whoosh bottle experiment filmed at 240fps.  The standard experiment involves setting light to methanol, ethanol or propanol in a polycarbonate water cooler bottle, and the rapid exit/entrance of gases through the neck causes a whoosh.

Filming in slow motion allowed us to discuss in much greater detail what was going on during the reaction, and to work out that the actual reaction is far more complicated than a simple equation.

The experiment was beautiful, filmed on an iPhone 6, and then slowed down in-app using SlowPro.

As an extra experiment, I then tried methanol in a volumetric flask, behind a safety screen in an empty lab, just in case.

A talking point and a teaching point.


Getting the lighting and safety aspects correct! (This is against CLEAPPS advice – never do this in an occupied lab)

Next Steps:

Using a TriggerTrip to take a high-res photo during the combustion process.

Simultaneous combustion of methanol, ethanol and propanol to compare burn rates and completeness of combustion.


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