Lycopodium Powder Fireball
Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★★☆ Can be done by science teachers
Safety: ★★★ Only to be attempted with adequate safety procedures and trained staff
Categories: Combustion, Explosions, Reaction Rate, Science Shows
Alternative titles: Dust Explosion Demonstration
Summary
Lycopodium powder, when ignited in a pile, burns slowly due to limited oxygen contact. When dispersed as a fine dust cloud and ignited, the vastly increased surface area causes rapid combustion, producing a dramatic fireball or small explosion.
Procedure
Part A. Slow combustion
- Place a small pile of lycopodium powder on a ceramic mat.
- Ignite it carefully with a propane torch or lighter.
- Observe that the powder smolders or burns slowly with only a small flame because oxygen contact is limited.
Part B. Dust explosion (paint can setup)
- Prepare a paint can with a small lit candle inside, positioned opposite a funnel connected to tubing and a squeeze bulb.
- Fill the funnel halfway with lycopodium powder and secure the lid of the can.
- Step back and squeeze the bulb firmly (or in quick bursts) to disperse powder into the flame.
- Watch as the powder cloud ignites, producing a fireball and often lifting or blowing off the lid.
Alternate method (fireball through funnel)
- Scoop two spoonfuls of powder into a funnel attached to tubing with a mouthpiece.
- Place a lit candle on a support such as an inverted beaker.
- Position the funnel opening just below the flame and blow powder through it to create a dramatic fireball.
- Caution: do not inhale powder; ensure audience is a safe distance away.
Links
EpicScience - Burning Lycopodium Powder - EpicScience:
Lycopodium Powder Fireball Effect - IncredibleScience:
📄 Lycopodium Powder Combustion: https://bpb-us-w2.wpmucdn.com/u.osu.edu/dist/f/27613/files/2020/01/Lycopodium-Powder-Combustion.pdf
Variations
- Use different dispersal methods (squeeze bulb vs. blowing through tubing) to compare fireball size.
- Compare lycopodium powder with other finely divided flammable materials such as flour or non-dairy creamer.
- Conduct outdoors at night for maximum visual effect.
Safety Precautions
- Lycopodium dust can irritate respiratory systems; some individuals may be allergic—perform at the end of class and avoid exposing sensitive students.
- Always keep a fire extinguisher nearby.
- Conduct the demonstration away from students; if indoors, ask students in the front row to move back.
- Do not inhale the powder while preparing or blowing through tubing.
- Tie back long hair and remove flammable materials from the area.
- Ensure the can and apparatus are stable and thoroughly tested before use.
- Dispose of burned powder in trash and wipe surfaces with damp paper towels to avoid airborne dust.
Questions to Consider
- Why does a pile of lycopodium burn slowly, while dispersed powder explodes? (A pile has limited surface area in contact with oxygen; dispersal creates massive surface area and rapid combustion.)
- What gases are produced in the combustion of lycopodium powder? (Carbon dioxide and water vapor, along with hot combustion gases that expand rapidly.)
- Why do grain silos sometimes explode? (Aerosolized grain dust behaves like lycopodium powder, creating explosive conditions when dispersed in air and exposed to a spark.)
- How does surface area affect reaction rate? (Greater surface area allows more oxygen contact, dramatically increasing the reaction rate.)