Dust Explosion

 

 

Summary:  Particles of lycopodium powder are ignited by a candle in an enclosed can, causing the lid to blow off!

Hazards: 

Big bang, big flame.  Stand at a safe distance.  Never blow out the candle with your breath! 

Chemicals and Solutions: 

0.5 to 1.0 g lycopodium powder

Materials: 

explosion can with a hole in the side near the bottom the hole should the same size

as the rubber stopper attached to the bent glass funnel)

candle

pipet bulb

tongs

matches

bent glass funnel fitted with a rubber stopper

rubber tubing

Procedure: 

Bend the stem of a glass funnel to form a right angle and then slide on a one-hole rubber stopper.  Place the bent glass funnel inside the explosion can such that the rubber stopper fits snugly into the hole in the side of the can and the funnel itself is in an upright position. Attach rubber tubing to the stem of the bent glass funnel. At the other end of the tubing attach a pipet bulb.  Place  the  candle in the can such that the wick is approximately level with the funnel top.  Add lycopodium powder to the funnel.  Using tongs and a lighted match, light the candle.  Place the lid on firmly and evenly.  Quickly move away from the can and squeeze the bulb firmly.   An explosion, accompanied by a flame, will blow the lid high in the air.

Hint: 

As an alternate procedure a “Jack-O-Lantern can be carved from a pumkin and used as the "explosion can".  You'll have a flame-throwing pumpkin.

Discussion: 

Lycopodium powder, the spores of a common moss, consists of very small particles that burn very rapidly when sprayed into a flame.  The rate at which a solid reacts increases with increasing surface area.  The very fine particles of lycopodium powder have a very large surface area for a given mass.  Dust explosions have been known to happen in grain elevators.

 

To schedule a demonstration, please send an email to the demonstration lab.

 

Contact:

Eric Camp

Lecture Demonstration Technician

Bagley Hall 171

(206) 543-1606

ericcamp@uw.edu

 

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