Fire is one of the most ancient and powerful natural elements known to man, and it has captured our imagination since the dawn of humanity. The sight of flames leaping and dancing is both mesmerizing and terrifying, and has inspired countless myths, legends, and scientific investigations. One of the most intriguing mysteries related to fire is the question of what burns red. In this article, we will explore the science behind the fiery phenomenon and try to unlock its secrets.
The Nature of Fire
Before we delve into the specifics of what burns red, it is important to understand the basic principles of fire. At its core, fire is a chemical reaction known as combustion, which occurs when a fuel source (such as wood, gasoline, or paper) combines with oxygen in the air and is ignited by a spark or flame. This creates a chain reaction where the heat from the burning fuel further breaks down its molecules and releases more energy, in the form of heat, light, and various gases.
The Three Elements of Fire
In order for fire to occur, there are three essential components that must be present: fuel, oxygen, and heat. These are often represented as the three sides of a triangle, and if one is removed, the fire will go out. The fuel can be anything that is flammable or combustible, ranging from natural materials like wood and coal to petroleum products like gasoline and propane. Oxygen, which makes up about 20% of the air we breathe, is required to sustain the chemical reaction of combustion. Heat is the third element, which catalyzes the reaction and allows it to proceed rapidly, often reaching temperatures of thousands of degrees Fahrenheit.
The Colors of Flame
Now that we have a basic understanding of how fire works, we can turn our attention to the question of what burns red. In order to answer this question, we first need to understand the different colors that flames can exhibit. Contrary to popular belief, flames are not always yellow or orange, but can range from blue to green to violet to white, depending on their temperature and composition.
The Blue Flame
At the hottest end of the spectrum, flames burn with a blue hue. This is because at high temperatures, the excited molecules of gas emit more energy in the form of light, which appears blue to our eyes. Blue flames are often seen in natural gas stoves, propane torches, and welding equipment, where the fuel is burning at a high temperature and with ample oxygen.
The Yellow Flame
Most flames we encounter in everyday life are yellow or orange, and this is because the fuel is not burning as hot as in blue flames. As the temperature decreases, the gases emitted by the fuel contain less energy, and the light they emit appears more red and orange. This is why a candle flame, for example, appears yellow and flickering, as the wick burns at a moderate temperature and sustains a chemical reaction known as “incomplete combustion.”
The Red Flame
Finally, we come to the question of what burns red. It turns out that red flames are relatively rare, and only occur under specific conditions. Typically, red flames are seen when the fuel is burning incompletely or with a lack of oxygen. This creates a situation where the temperature is relatively low, and the light emitted by the flame appears more red and dull. Some common examples of red flames include iron heated to a high temperature, the burner on an electric stove set to low, and the embers of a dying fire.
The Chemistry of Red Fire
Now that we know what burns red and how flames create different colors, let’s look at the chemistry behind the phenomenon. To produce a red flame, there are two key factors at work: the presence of carbon and the temperature of the flame.
Carbon and Red Flames
Carbon is an elemental material that is found in many common fuels, such as wood, coal, and gas. When these fuels are burned, the carbon atoms in them are oxidized – or chemically reacted – with the oxygen in the air, creating carbon dioxide and water vapor. However, if there is not enough oxygen present, the carbon will not be fully oxidized and can instead form carbon monoxide or even elemental carbon, which can appear as soot or charcoal. If the flame contains soot or other carbon particles, it can appear red, as the carbon atoms tend to absorb more of the light in the blue and green wavelengths, leaving a reddish glow.
The Temperature and Red Flames
Another factor that influences the color of a flame is its temperature. As we mentioned earlier, flames that burn hotter tend to emit blue light, while cooler flames appear more yellow, orange or red. This is because higher temperatures excite the gas molecules more, causing them to emit higher-energy light such as blue and violet wavelengths. Conversely, lower temperatures tend to emit lower-energy light such as red and orange wavelengths. So when a fuel source is burning with a low amount of oxygen, it tends to create a cooler flame with more carbon particles, which can appear red.
The Applications of Red Flame
Red flames may not be as common as other colors, but they have a number of interesting applications in science, industry, and art. Here are some examples:
Pyrotechnics
In the world of fireworks and pyrotechnics, red flames are often used to create dramatic effects. Red fireworks are created by adding strontium compounds to the mixture, which burn at a lower temperature and create a distinctive red glow. The same principle is used in flares and other signaling devices, where a red flame is highly visible and can be seen from afar.
Metallurgy
The production of certain metals, such as iron and steel, requires high-temperature furnaces and kilns. These can produce red flames as the metal is heated and its impurities are burned off. In some cases, the red flame can be an indicator of the metal’s quality, or of any impurities that may be present.
Artificial Lighting
Many artificial lighting sources, such as light bulbs and neon signs, use gases that emit different colors of light when energized. Some of these gases, such as neon and argon, can create a red glow when excited by an electrical current. This has led to the use of red light in a variety of artistic and commercial applications, from glowing signs to theater lighting to mood lighting.
Conclusion
So what burns red? The answer is a bit complicated, as it depends on a number of factors such as temperature, composition, and oxygen availability. However, we can say that flames that contain incomplete combustion, soot, or carbon particles tend to appear more red, as do flames that are burning at a cooler temperature. Red flames have been used for centuries in a variety of creative and practical applications, from pyrotechnics to metallurgy to lighting. We hope this article has unlocked some of the mysteries of this fiery color and given you a deeper appreciation for the power and beauty of fire.
Frequently Asked Questions
- Q: Why do some flames burn blue, while others are yellow or orange?
- Q: What types of fuels tend to produce red flames?
- Q: Why are red flames used in pyrotechnics?
A: The color of a flame depends on its temperature and composition. Blue flames burn hotter than yellow or orange flames, and contain excited gas molecules that emit blue-light wavelengths.
A: Fuels that burn incompletely or with insufficient oxygen tend to produce red flames, as the carbon particles in the flame absorb more of the blue and green wavelengths of light, leaving a red glow.
A: Red flames are highly visible and can create dramatic effects in fireworks and other pyrotechnics. They are often created by adding strontium compounds to the mixture, which burn at a lower temperature and emit a distinctive red glow.
References
- Chang, R. (2005). Chemistry (9th ed.). New York: McGraw-Hill.
- Encyclopedia Britannica. (2021). Flame. In Encyclopedia Britannica online. Retrieved August 15, 2021, from https://www.britannica.com/science/flame.
- RSC Chemical Sparks. (n.d.). The Chemistry of Fireworks : red, green, blue and bang. Retrieved August 15, 2021, from https://edu.rsc.org/resources/the-chemistry-of-fireworks-red-green-blue-and-bang/456.article.