Co-Authored by Dean J. Campbell*, Kristine Campbell*, and Katie Campbell, *Bradley University, Peoria, Illinois
Blowing flammable lycopodium powder from a tube onto an open flame produces a fireball in a spectacular demonstration of fast reaction rates when reactants have high surface area. The purpose of this variation on the “dragon’s breath” demonstration is to illustrate that face masks can diminish the movement of particles in the air, an important idea in public health.
Video 1: Lycopodium Dragon Sneeze with a Face Mask on the author's YouTube Channel (accessed June 22, 2020)
In the demonstration, the lycopodium powder (made of spores from small plants called clubmosses) is first blown through a tube with a dragon design at one end and no flame present to illustrate the appearance of the powder puff. In this version of the demonstration, the powder is blown through the tube using a squeeze bulb from a Stomp Rocket set. Safety considerations include wearing goggles and using a fire-resistant environment (see safety links below). The tube is reloaded, but this time a face mask covers the mouth of the dragon at the end of the tube, and a propane torch is lit several centimeters away from the dragon's mouth. When the powder is blown through the tube, most of it is caught by the dust mask and no fireball forms. The “dragon sneeze” (or cough) is caught by the mask. Finally, the mask is removed, and the powder is blown through the tube into the flame to make a fireball. Here, without the mask, much more powder gets to the flame. In a similar way, NOT wearing a face mask can allow more material (including germs) to leave a person's mouth and get into the surrounding environment.
Editor's Note: This demo is an extension to the previously published article "Chemical Illustrations of Flattening the Curve".
Safety
Safety: Video Demonstration
Safety: Video Demonstration
Demonstration videos presented here are not meant as tools to teach chemical demonstration techniques. They are meant as a tool for classroom use. The demonstrations may present safety hazards or show phenomena that are difficult for an entire class to observe in a live demonstration.
Those performing the demonstrations shown in this video have been trained and adhere to best safety practices.
Anyone thinking about performing a chemistry demonstration should first read and then adhere to the ACS Safety Guidelines for Chemical Demonstrations (2016) These guidelines are also available at ChemEd X.
General Safety
General Safety
For Laboratory Work: Please refer to the ACS Guidelines for Chemical Laboratory Safety in Secondary Schools (2016).
For Demonstrations: Please refer to the ACS Division of Chemical Education Safety Guidelines for Chemical Demonstrations.
Other Safety resources
RAMP: Recognize hazards; Assess the risks of hazards; Minimize the risks of hazards; Prepare for emergencies
NGSS
Students who demonstrate understanding can apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.
*More information about all DCI for HS-PS1 can be found at https://www.nextgenscience.org/dci-arrangement/hs-ps1-matter-and-its-interactions and further resources at https://www.nextgenscience.org.
Students who demonstrate understanding can apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.
Assessment is limited to simple reactions in which there are only two reactants; evidence from temperature, concentration, and rate data; and qualitative relationships between rate and temperature.
Emphasis is on student reasoning that focuses on the number and energy of collisions between molecules.