One of my favourites is still an old classic that I saw in a chemistry lesson when I was about 10. The teacher collected lots of carbon dioxide a large jar using a burning candle and then poured it onto the candle, extinguishing it, and spreading smoke across the desk. I knew nothing about gases and combustion and it was a pretty amazing (and simple) demonstration of very simple chemistry.
Being a chemist I like the more explosive reactions! A favourite is the thermite reaction.
Iron oxide (rust) and aluminium powder are mixed together – a totally unreactive powder. When you set fire to it with a magnesium ribbon fuse though, it makes lots of smoke and heat and the end product is a blob of hot molten iron. This reaction is used to hold lengths of railway rails together.
Reactions of hydrogen gas and oxygen together are also pretty good!
When we got the first “fringes” back from our EMerlin linked telescope system – we’d been looking and looking, changing the setup a bit and looking again, and finallly there was a boring looking spike in the data. Success after months of hard work, including weekends and late nights.
(The boss opened a bottle of champagne 🙂 )
It uni on every 5th November the chemistry department put on an explosives lecture. Can I take the whole hour lecture rather than one specific experiment? The best one I think was to show the energy contained in carbon carbon bonds. Three glass milk bottles (it was a few years ago) filled with ethane, ethylene and acetylene. The ethane one had a pretty yellow flame when lit. The ethylene one was put inside a can and after lighting was reduced to bits of broken glass. The acetylene was put into a thick steel tube and lit with a 4 meter long metal rod with a taper on the end. The rod bent into a two like a hair grip and there was no glass in the steel tube.
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