Dust Explosion

Equipment

25 x 20 cm can with tightly fitting cover and a bulb funnel attachment for dispersing powder, candle or gas, 8 cm funnel, watch glass, barbecue lighter.

Reagents

2 mL of dry lycopodium powder.

Presentation

1. Place small pile of lycopodium powder on a watch glass.
2. Try to ignite the pile with the lighter.
3. Place lycopodium powder in funnel.
4. Let the powder settle before lightning the candle or gas.
5. Place plug in hole used for lighting the gas or candle.
6. Cover the can securely.
7. Press bulb to disperse the powder.
8. Explosion shoots cover in air and flame rises to around a height of 2 meters.

Hazards

Stand back to avoid the flying lid and flames. Lycopodium powder is very flammable. Low hazard may cause eye and/or skin irritation, may cause gastrointestinal irritation (nausea, vomits, diarrhea), if ingested may cause respiratory irritation, if inhaled possible asthmatic attack.

Discussion

Lycopodium powder is the spore from club moss. This demonstration illustrates the increase in a reaction rate with an increase of surface area. With the lycopodium was in a pile, the exposed surface was relatively small and the rate was so slow as to be non-existent. When the powder is blown out of the funnel, the surface area is huge and the combustion reaction rate is so fast that it becomes explosive.

References

1. Alyea and Dutton, p. 8(2-17).