How do Fireworks Work? Fireworks are made up of several components:

• Gunpowder - a mixture composing of: 75% Potassium Nitrate (KNO3), 15% Charcoal (Carbon), and 10% Sulphur.
• Casing - Thick cardboard or paper rolled up into a tube.
• A fuse - cotton twine coated with gunpowder.

The gunpowder/fuel (which provides thrust for most fireworks) is tightly packed into the casing forming the propellant-core of the rocket in a length to diameter ratio of 7:1. e.g. 14cm long and 2cm in diameter.  The fuse is lit by a match and then the fuse burns rapidly into the core of the rocket where it ignites the gunpowder walls of the interior core.  Gunpowder contains potassium nitrate, which is the most important ingredient.  This is because of the molecular structure of KNO3, which is made up one potassium atom (K), one nitrogen atom (N), and three oxygen atoms (O3).  Since fire needs oxygen to burn the O3 is very important because it causes the KNO3 to release the oxygen, thus potassium nitrate oxidises the chemical reaction.  This reaction is not impulsive and must be started by the heat of the match or something else hot.

What Makes the Different Colours?

Adding different inorganic/metallic salts to the gunpowder mixture generates the colours of a firework.  Barium salts produce greens, strontium makes red, sodium makes yellow/orange, potassium makes purple.  The whites and golds are made with mixtures of iron, magnesium, and aluminium and using copper salts produces blues, but this isn’t all that happens.  One way is when the shell explodes the flames (heat) gives the electrons of the atoms extra energy causing the electron to jump to a higher energy level (or shell).  When the electrons cool down they get rid of this extra energy in the form of a light particle (each element give a different light of the light spectrum) and the electron moves back down to its original energy level/shell.