This is the classic basic chemistry experiment: a (very!) small piece of sodium is dropped into a water beaker. The violent reaction causes the sodium to ignite and whizz on the surface of the water. The reaction is very exothermic, meaning it releases a lot of heat, and produces sodium hydroxide, which makes the water turn alkaline. This is a dangerous experiment if done wrong.

So post World War II, the USA had a few tons of sodium to dispose of. How did they do it? By dumping it in batches into a lake. The lake was already alkaline, so not (too) much harm there. But the beauty of this is the demonstration of just how violent the reaction between sodium and water is: it's explosive, even if the water is icy cold. With this little intro, I leave you with the video below:

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