Yesterday, I went to see some fireworks that my town was having. As always, I thought of the chemical compositions of the fireworks while watching the display.
Fireworks are colored using several elements. A green coloration is obtained using barium or some forms of copper. A rarer blue coloration can also be obtained by copper. A purple coloration is produced with potassium, while an orange coloration is produced with calcium. Either lithium or strontium can be used to create a red color. Combinations of colors are produced by layering these various elements in the pyrotechnic mixture. As it burns up, the different colors are shown.
Some fireworks leave streams of glowing particles behind or produce an array of sparks. If the particles are a dull orange, then they consist of iron filings. If they are bright white, they are most likely magnesium. If they are slightly orange, they could be either aluminium or titanium powder.
My favorite fireworks were the flash powder ones. While I am not definite about the composition, bright flash powders are often made using magnesium powder and potassium perchlorate. This mixture is quite stable until it is ignited, after which it burns rapidly. Enclosing this easily makes a bright spot in the sky and a loud bang as the enclosing material is torn apart, similar to a flash-bang grenade.
Plain and simple chemistry is not the only element necessary to create a dazzling fireworks display. The physical arrangement of fireworks can provide a variety of effects. Here are several pages detailing the physical aspects of fireworks.
Enjoy the fireworks this holiday season (for US readers) and remember the intricacies of chemistry that produce the dazzling effects.