Chemical of the Week 4 – Thermite

imageSo how long could I blog before I mentioned the chemical composition that is – THERMITE – now that’s got your attention ! Described on wikipedia as a pyrotechnic composition of metal powder fuel and metal oxide but that really does not do it justice. Well what does then ? It has to be the Brainiac clips dedicated to blowing up a French car…

https://m.youtube.com/watch?v=GyVD8V0016w

For the older readers look no further than Breaking Bad. One of my favourite scenes is when Walt and Jessie use the thermite reaction to create an explosion in order to open a methylamine store. Now, using filings from an etch-a-sketch as the reactants may just be a chemical step to far !

So how can we squeeze this little cracker into a scheme of work – for me it works best in KS3 introduction to Redox. The thermite reaction (it can have different components) of aluminium and iron oxide is the perfect example of a redox reaction – the iron oxide loses oxygen whilst the aluminium gains it. It does need an ignition and magnesium or potassium permanganate/glycerol can be used. The highly exothermic nature of the reaction and the high activation energy are good AS discussion points.

The thermite reaction was discovered in 1893 by Goldschmidt and its first commercial application was in 1899 when it was used to produce molten iron to weld tram tracks in 1899. But my favourite use has to be within the military where it is used in the emergency destruction of cryptographic equipment when there is a danger it might be captured by enemy troops – there’s one for the next James Bond movie.

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