Fire-the-works-up

Yet again I missed out on an opportunity for fireworks and celebration. I didn’t even have some kind of sexy drink with my all-time favorite Perspectives in Chemistry teacher, Dr. Daphne Norton. This 4th of July was a sad reminder that I have only seen fireworks on that day twice in my life. Growing up in another country and then for the last 8 years that I have lived in America, not being in the U.S. for the big day, I have missed out on a great many of these colorful night-time displays. As a tribute to my failed attempt at being patriotic this year, I will instead approach the subject of fireworks from another entertaining point; CHEMISTRY.
Every High School student spent at least one day in a chemistry class in which you could throw some different metals into a flame and watch the pretty colors. If not, then those left surely have at some point in their lives thrown some table salt into a flame and watched the effects as it burned. Throughout time the basic theory behind the chemistry has been used in many versatile ways: art, gun powder, photography, elementary science fair projects, and pyrotechnics. But what is actually happening?
Much thought goes into creating fireworks. Not only do you get different patterns in the sky and different colors, but you also get different kinds of light emitted. The colors of the fireworks come from metal compounds such as strontium (red), aluminum (white), magnesium (white), and copper (blue) among others. These can burn as either incandescent or luminescent light. The first uses light produced from heat, the second uses an energy source other than heat and thus can sometimes be called “cold light”. Incandescent fireworks give many of the orange, yellow, and white colors as increasing temperatures with different compounds. Luminescence comes from the absorption of light by an electron that becomes excited and unstable, when the electron jumps back to its stable, ground state it emits light. This principle can be used in different analytical chemistry techniques such as atomic absorption [spectra] (AAS).
The different chemical components of fireworks are as follows: an oxidizing agent, a reducing agent, a coloring agent, and binders and regulators. Because the nature of fireworks is a combustion reaction an important part of this reaction is oxygen to burn the mixtures. This is provided by the oxidizing agent, commonly nitrates, chlorates or perchlorates. Next, reducing agents burn the oxygen to create hot gasses. A combination of reducing agents can be used to speed or slow the process. Two such reducing agents are Sulfur and charcoal. The coloring agents are as mentioned, different compounds such as, strontium salts and lithium salts for red colors, aluminum, titanium, or magnesium for silver or white, and sodium compounds for yellow colors. The last two elements of fireworks are not very chemical, but rather there for the physical aspect of packaging and the resulting shapes of the fireworks.
I hope this gave some insight into the colorful and creative side of chemistry and the festivities created by its many uses.

Works Cited:

http://www.scientificamerican.com/blog/60-second-science/post.cfm?id=bombs-bursting-in-air-whats-in-thos-2009-07-03
http://chemistry.about.com/od/fireworkspyrotechnics/Fireworks_Pyrotechnics.htm
http://library.thinkquest.org/15384/chem/index.htm
http://chemistry.about.com/od/fireworkspyrotechnics/a/fireworkcolors.htm