How Fireworks Brighten Up Our Sky

By Justine Dator

Every February to March, the Philippines hosts the Philippines International Pyromusical Competition.Different countries exhibit spectacular displays of light that dances to music from different genres and generations. The skyline of Manila is lit by fireworks that explode into different colors and patterns. But, did you ever wonder what exactly these fireworks are made of? What chemical interactions are needed in order to achieve the different colors of fireworks?

The different colors of fireworks are produced by heating different metal salts in different combinations in order to produce the desired colors. Each element absorbs the energy as it is being heated, and this energy rearranges the electrons of the atom from their low-energy state (ground state) to their high-energy state (excited state). The energy in excess emits in the form of light, and the color of the light is determined by the amount of energy emitted. The table below summarizes which colors are made from which salts.

COLOR

COMPOUND

Red

Strontium salts & Lithium salts

Orange

Calcium salts

Yellow

Sodium salts

Green

Barium compounds (+chlorine producer)

Blue

Copper compounds (+chlorine producer)
Gold

Iron compounds

Silver

Burning aluminum, magnesium, or titanium

 

Purple-colored fireworks can be made by combining Strontium (red) and Copper (blue) compounds.

Fireworks are made by creating lumps of clay called ‘stars’, which are a combination of key materials in making fireworks. It has oxidizing agents, reducing agents, the coloring agents (metal salts), and binders. The role of the oxidizing agents is to produce the oxygen needed for the mixture to burn. Some agents include nitrates, chlorates, and perchlorates. Reducing agents burn the oxygen produced by the oxidizing agents to produce hot gasses. The binders essentially hold together the firework mixture. Lastly, a fuel is required to light the firework up into the air. The most commonly used fuel is black powder. When burned in open air, the heat and gas emitted from the ignition dissipate in the air.

When fireworks are lit, a boom can be heard from ground level. Since the ignition caused a rapid release of energy, the air around it expanded faster than the speed of sound, which produces a sonic boom.

A great deal of effort and precision is involved in the creation of fireworks. Every component must be handled delicately and exact quantities must be measured to ensure a stable and safe reaction. Now you know what makes fireworks, fireworks!

 

References:

[1] http://www.ch.ic.ac.uk/local/projects/gondhia/composition.html

[2] http://scifun.chem.wisc.edu/chemweek/fireworks/fireworks.htm

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