The Chemistry of Fireworks

The composition of a basic firework is quite simple. All fireworks consist of four basic parts:

An Oxidizer

Oxidizers produce oxygen to burn the mixture. Oxidizers are usually nitrates, chlorates, or perchlorates. Potassium nitrate is the most commonly used oxidizer in amateur fireworks. However, potassium chlorate and potassium perchlorate are much cooler.

Potassium Nitrate : 2 KNO3(solid) --> 2 KNO2(solid) +O2(gas)
Potassium Chlorate : 2 KClO3(solid) --> 2 KCl(solid) + 3 O2(gas)
Potassium Perchlorate : KClO4(solid) --> KCl(solid) + 2 O2(gas)

As illustrated by the above reactions, one molecule of potassium nitrate only produces one molecule of oxygen. However, one potassium chlorate produces three oxygen molecules and one potassium perchlorate produces four oxygen molecules. We will be playing with all three.

A Fuel The fuel burns the oxygen produced by the oxidizer. The fuel is often a mixture of charcoal and sulfur.
Powdered Metal The metal creates the sparks. Iron, steel, and aluminium are commonly used. We will be using aluminum, as well as experimenting with magnesium in stars.
A Combustible Binder The binder holds everything together. Some firework formulations simply use the binder as the fuel. The binder is usually sugar, starch, or shellac.

Additional compounds may be added for color, or to control the rate of the reaction.