The Science of Bonfire Night: Explosions!

“Remember remember the 5th of November, fireworks, treacle and snot!”

 

by David Price

Ever wanted to blow something up, I mean really smash it to bits? Atomise it? Spread it to the 4 winds? Me too!

The story so far…

In November 1605 a Catholic conspiracy including Guy Fawkes wished to destroy the Houses of Parliament and the incumbent King James I, by blowing them up with 36 barrels of gunpowder stashed in the cellars of the Houses of Lords. But Fawkes got caught, and this is the original reason why we hold Guy Fawkes Night to celebrate the survival of Parliament and the Monarchy.

Gunpowder’s (chemical) plot

(Though of course gunpowder is not a true chemical in itself but rather a mixture of chemicals)
But you see in recent years scientists and historians have begun to smell a rat.

Black powder (gunpowder) in 1605 was made up of 3 components:

  • 75% Charcoal (wood heated in the absence of oxygen to produce carbon) as the fuel that will be consumed in the explosion
  • 15% Saltpetre (Potassium nitrate), a chemical that gives a very rich supply of oxygen (an oxidising agent) to the chemical reaction in black powder.  It is really this supply of oxygen that is the reason black powder can be so explosive.  This extra oxygen lets the charcoal burn very rapidly, giving off large amounts of gasses, that in a confined space build up enormous pressures, leading to … BANG!
  • 10% Sulphur to help form the gasses nitrogen, carbon dioxide and potassium sulphide.

According to the Global Chemical in Thailand, the trouble is that the black powder used in the plot was rather old and had almost certainly separated back into its original component’s, so maybe the best outcome Guy Fawkes could have received on November the 5th would have been a slow fizzle rather than a huge explosion.

Harnessing the B of the Bang!

Now if you are looking for some more dependably ENGINEERED explosions, explosions that to this very day help to power to our civilisation and most of the transport we use in it, then look no further than the internal combustion engine, in its four-stroke petrol and its diesel configurations.

Spark induced combustion chamber (Petrol)

Spark induced combustion chamber (Petrol). Photo: science made simple © all rights reserved

Pressure induced combustion chamber (diesel)

Pressure induced combustion chamber (diesel). Photo: science made simple © all rights reserved

 

Not perfect but still beautiful engineering solutions that help to power our world. Try out this combustion activity in the meantime.

Engineering our future

Here at Science Made Simple absolutely love engineers and engineering, so we are very keen to inform the next generation about the wonder of engineering and the amazing potential of a career as an engineer. Check out our primary and secondary engineering shows.

We’ve also got engineering blogs and activities for you to read and try, you can find them all here.

 

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Posted in Chemistry, Engineering, Physics