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ChemWiki: The Dynamic Chemistry E-textbook > Development Details > Approaches > Demos > Additional Demos > Dust Can Explosion-- Lycopodium Powder Combustion

Dust Can Explosion-- Lycopodium Powder Combustion

Chemical Concept Demonstrated

  • The relationship between the rate of a reaction and the surface area available for the reaction

Demonstration

The dust-can explosion apparatus consists of:
  • A small funnel attached to piece of rubber tubing that has been threaded through a hole in the bottom of the 1-gallon paint can.
  • A rubber pipet bulb attached to the other end of the rubber tubing.
  • A candle placed next to the funnel inside the can.
  • A small amount of lycopodium powder inside the funnel.
dust.gif

Light the candle, replace the lid, and squeeze the bulb several times to eject the dust in the can.

Observations

When the bulb is squeezed, flames shoot out of the top of the can.   This can be repeated several times.

Explanation

When the bulb is squeezed, the powder in the funnel is dispersed into the air.  As the powder touches the candle, it ignites.  The entirety of the airborne powder catches on fire.  However, the powder that is still in the funnel is unaffected, as it can be shown that more such bursts of flame can be produced. 

The powder still in the funnel has less surface area than the dispersed powder.  The airborne powder catches on fire, but the funnel powder does not.  As an alternate method, one could simply place a sample of lycopodium powder on an asbestos pad, hold burner to it in this "compact" state, then initiate the dust can explosion.

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Last Modified
10:28, 2 Oct 2013

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