Potassium Chlorate & Aluminum

A mixture of potassium chlorate and aluminum produces fireworks.

Flash powder is a mixture of ingredients that burns so rapidly that the eye perceives an instantaneous flash. Flash powder provides the propulsion and the explosion for fireworks and sometimes the flash in photography. Aluminum powder and potassium chlorate are often ingredients of flash powder.

Fuel

Aluminum powder serves as fuel in flash powder. The small aluminum crystals are often imperfect; the imperfections make it a more efficient fuel. Aluminum powder also burns better if the powder grains are smaller--about five microns (five millionths of a meter) in diameter.

Oxidizing Agent

Potassium chlorate is an efficient oxidizing agent. It liberates oxygen rapidly enough to support the instantaneous combustion needed in such devices as fireworks.

Dangerous Combination

A mixture of potassium chlorate and aluminum powder is a dangerous combination. A spark may cause an explosion. A vigorous bump or even friction may produce the same result.

Color

In addition to its role as an oxidizing agent, potassium chlorate adds color to a fireworks display. The addition of other metals results in a variety of colors.

References

• Springerlink: Characterization of the Aluminum/Potassium Chlorate Mixtures
• Private Data: Impact Firecrackers
• Chemical Land 21: Potassium Chlorate
• Science Direct: A Study of Deformed and Recovered Aluminum Crystals
• All Business: A Blast From the Past Continues--The Ongoing Saga on Fireworks

Resources

• Practical Chemistry: Catalysts for the Thermal Decomposition of Potassium Chlorate