I don’t mean to light up the room, but this blog is going to be a blast! Have you ever been to a firework show and wondered how do they make fireworks? What makes them so loud, and how are they launched so precisely and bright? What makes them different colors anyway? The answers to these questions can all be answered with chemistry. That subject some may find boring can be fascinating once we understand it. This is true of fireworks, pyrotechnics, and neon lights. They include chemical principles, such as combustion, redox reactions, and flame colors.
This blog is intended for everyone, whether you are just curious about fireworks, or you plan to become a pyrotechnic engineer ( the people who make and launch fireworks for a living). We will learn about line spectra and the Bohr model of the atom. We will discuss what a pyrotechnic does and what kind of degree they have, and how neon lights are all connected to fireworks and explained with chemistry.
Let’s shed some light on the subject of noble gas illumination. These are the result of the line spectra from the Bohr model which we will discuss later in the blog. Discovered in 1898 by Sir William Ramsay and Morris Travers during their experiments with liquid air, neon accounts for 18 millionths (18 ppm) of the volume of Earth’s atmosphere (Mowart, 2004).You may be familiar with the Periodic table of the elements. Noble gases are a group of the periodic table in the p-block, or the rightmost column. Nobel gases react very unwillingly, because the outermost shell of the electrons orbiting the nucleus is full, so they do not swap electrons with other elements. Neon (Ne) is one of the more fun elements. When you hear neon the first thing your probably think of is a big neon sign. Neon bulbs were developed by French engineer Georges Claude in 1902. To make a neon sign, first electrodes are placed on both ends of a glass tube filled with neon or argon gas connected to alternating current. Fifty times a second, the charge on each electrode will alternated a positive and negative charge. Free electrons in the tube have a negative charge so they are drawn to the positively charged electrode. In this process the electrons crash into the molecules of neon or argon, knocking lose more electrons.
The loss of the electrons leave the gas molecules positively charged and the become excited. As they fall back to their ground state, they give off light. It is the glow of the neon sign.
You may have noticed different colors of neon lights. The color of the neon sign comes from the color given off by the gases as well as the color of the glass and different fluorescent powder coatings applied to the glass.
The colors from fireworks are produced from different elements. For example, if you were to sprinkle table salt on a fire, it would produce a yellow flame. A salt containing copper will give a blue-green flame, and lithium salts a red flame. If we were to examine a flame through a spectroscope (uses a prism to break up light in to different components) you could observe the line spectrum. A Danish physicist by the name of Niels Henrik David Bohr (1885-1662) explained this line spectrum while developing a revised model for the atom. At first the Bohr theory was a theory that explained the behavior of hydrogen atoms. In the years to come he extended the theory to encompass all elements and to provide an explanation of the Periodic Table (Bostrup,2004). He suggested that electrons exist in very specific regions at defined distances from the nucleus. These orbits can be thought of as the rungs of a ladder. As a person climbs up a ladder, they step on one rung or another, but not in between rungs, because a person cannot stand on air. Likewise, the electrons of an atom can occupy one orbit or another, but cannot exist in between orbits (Lee & McGarth, 2014). The electrons then move about the nucleus in circular orbits at a fixed distance from the nucleus, like planets around the sun. These different energy levels are sometimes referred to as shells ,describing different levels of energy. This high-energy state does not last long. Excited electrons of calcium chloride release their energy, about 628 kj/mol, which is the energy of orange light.
The different amount of energy released will be a characteristic of a particular element and will determine a specific wavelength of light. The higher energies will have a shorter wavelength of light, and located in the violet/blue region of the spectrum. Lower energy will produce longer wavelengths of light.Each substance, given a different energy, has its own “fingerprint” on the spectrum
Fireworks generate three very noticeable forms of energy: Heat, a very loud sound and a bright light. When you hear the sound at ground level, it is the rapid release of energy in the air causing a shock wave, a sonic boom (Conkling, decker, 1985). Some fireworks will be louder than others depending on their grade (commercial vs home grade). Even the atmospheric conditions can play a role making some the same fireworks sound louder some nights than others . The gas and the heat build inside of the firework shell causing the explosion that releases a lot of energy at once. The blast wave causes a particular wave form known as Friedlander Waveform . After the explosion the surrounding air is over-pressurized, causing the compressed air particles to travel faster than the speed of sound. The waveform is quickly decays causing a period of negative pressure known as rarefaction. The power of the sound is proportional to the pressure squared.
If becoming a pyrotechnic engineer sounds interesting to you here are some details:
Pyrotechnic engineers work with explosives and reactive chemicals to create fireworks. Their jobs require an extensive knowledge on how certain compounds will react with other inputs to produce pyrotechnic displays. They must have extensive knowledge in both chemistry and physics to accurately determine how a reaction will occur. Their job may include many aspects of making explosives happen, from testing materials to making precise measurements and calculations of each chemical compound.
There are no formal education programs at large universities for pyrotechnic engineers, so candidates must be self-motivated to take the required classes to give them the knowledge that they need. A pyrotechnic engineer would start with an undergraduate degree in chemistry or physics, and then further their education in pyrotechnics. Because it can be such a dangerous job, some states will require a licensing exam.
Most jobs require a Bachelor’s degree in chemical engineering, chemistry or related field. In addition to a degree, other requirements would include fireworks training and certification (may vary state to state). The mean salary (2015) $103,960.00 for all chemical engineers. Some job will pay depending on the amount of shows you do per year if getting paid on a commission (sources: U.S. Bureau of Labor Statistics)
The chemistry of fireworks is fun to learn about because it connects stunning pyrotechnic displays we look forward to every year to fascinating jobs in the field of chemistry and engineering. We see the Bohr line spectra in jaw-dropping fireworks as well as spectacular neon signs. Who knew that electrons becoming excited could be so interesting! Next time you go to the Las Vegas, or Walgreens, you will know how those bright neon signs are made and what is going on inside those bulbs is chemistry. Maybe someone reading this may actually decide to become a pyrotechnic engineer!
ez1.maricopa.edu:2048/login?url=http://go.galegroup.com.ez1.maricopa.edu/ps/i.do?p=GVRL&sw=w&u=mcc_chandler&v=2.1&it=r&id=GALE|CX3400900066&asid=b400593364513d4ca7fb23563d21f201Reference USA, 2004, pp. 129-130.
Conkling, Decker, (1985). Chemistry of Pyrotechnics: Basic Principals and Theory.
Lerner, K. Lee, and Jennifer McGrath. “Atomic Models.” The Gale Encyclopedia of Science, edited by K. Lee Lerner and Brenda Wilmoth Lerner, 5th ed., vol. 1, Gale, 2014, pp. 402-407. ez1.maricopa.edu:2048/login?url=http://go.galegroup.com/ps/i.do?p=GVRL&sw=w&u=mcc_chandler&v=2.1&it=r&id=GALE|CX3727800231&asid=54928c4b494ee443c61463a5ff8f6e4b.
Mowat, Richard. “Neon.” Chemistry: Foundations and
Reference USA, 2004, p. 130. & ez1.maricopa.edu:ez1.maricopa.edu:2048/login?url=http://go.galegroup.com.ez1.maricopa.edu/ps/i.do?p=GVRL&sw=w&u=mcc_chandler v=2.1&it=r&id=GALE|CX3400900338&asid=aad870c99d27e06ff49143d5b3bc90a5