I went to the Science Museum in London some time ago and saw a brilliant demo attempting to show that sugar has a lot of energy in it. Having tried to set fire to a pile of granulated sugar on a heat-proof mat, the demonstrator then tried the same with icing sugar, which of course has smaller grains. Still no ‘whoof!’ of flame. She then talked about surface area and the difference this makes in a reaction. Asking the children how she give the pile of icing sugar a lot more surface area, we then bashed out the idea that letting it spread out by getting it airborne should increase the surface area of the whole pile of sugar, allowing oxygen to react at all surfaces on each speck of sugar.
Out comes a funnel, metres of rubber tubing attached and a foot-pump on the other end, which is then clamped upright under a blow-torch flame. One pump on a foot-pump pressurises the air in the rubber tubing which then lifts a pile of icing sugar that we put into the top of the funnel. Now it goes it goes ‘whoof!’
Anyway, my technicians and I had a go at doing the same in an empty lab. We clamped a lit Bunsen burner over the funnel, duly put on lab coats and safety specs and stood back. The distance to the ceiling was at least 2 metres, but the flame still hit the ceiling and rolled across it. Perhaps we don’t pump so hard next time!
Again, thanks to the Raspberry Pi for letting me get this slow-motion video 🙂