Senior Chemistry Discrepant Event
Title: Dust Can Explosion – Lycopodium Powder Combustion
Purpose: To show the relationship between the rate of a reaction and the surface area
available for the reaction.
Grade Level: Grade 12 University Preparation (SCH4U)
Topic from Ontario Curriculum: Energy Changes and Rates of Reaction unit.
Specific Expectation - explain how factors such as
temperature, surface area, nature of reactants, catalysts, and concentration control the rate
of chemical reactions.
Theory: When you blow the powder out of the funnel, the powder is dispersed into the
air. As the powder touches the candle, it ignites and the entirety of the airborne powder
catches on fire. The dispersed powder has more surface area than the powder sitting
together in the funnel and is able to react and therefore ignite.
Materials: metal can, lycopodium powder, funnel, hose, candle, matches.
Procedure: Setting up apparatus:
- punch a hole in the bottom of a metal can
- feed funnel through from inside the can and attach a hose to the funnel
- have a candle sitting inside the can beside the funnel
Demonstration:
- pour some lycopodium powder onto lid of can and try to ignite it using a
match
- fill funnel already inside can with powder
- light candle and place beside funnel inside can
- place lid over can
- have volunteer blow through hose attached to funnel
- explosion will occur in can, blowing lid off
Hints for Success: Make sure you show students that lycopodium powder will not ignite
when placed in a compact state.
Safety Considerations: Keep away from heat or ignition source.
DO NOT BREATHE DUST.
Reference: http://chemed.chem.purdue.edu/demos