The dance of flames in a fireplace or campfire can melt away the stress of a long day, lulling us into a state of complete relaxation. In fact, researchers have found that just watching a fire lowers one’s blood pressure. While there are many benefits to enjoying a roaring fire, we must remember to always be safe and follow Smokey’s ABCs: Always Be Careful with Fire.
Despite its seemingly magical powers, fire is not magic. Instead, it is the result of a chemical reaction. Fire is the rapid oxidation of a material in the exothermic process of combustion, releasing heat and various reaction products. During combustion, carbon dioxide and water are produced, along with the characteristic blue flame that we see.
Fire is not just for warmth and cooking — it’s also essential to certain species of plants. Many trees such as hickory and oak need periodic fires to sanitize their bark and encourage nutrient-rich soil for new seedlings to grow. Fire also helps open up sand plains so that a variety of plants can flourish there.
So, how does fire work? Typically, something — such as a match, focused light or friction from a rake — is used to get the fuel up to the ignition temperature. Once the fuel has reached that point, it begins to burn by a process called decomposition, in which the plant fibers that make up the wood break apart, forming volatile gases and other products that react with oxygen to produce fire.
As the gas molecules move, they emit light — an effect known as incandescence — which is why we call it a flame. The light is created by the atoms in the molecules moving to higher energy levels as they lose energy — and then jumping back down to a more base level. This is the same type of process that occurs when an ice cube melts or silver tarnishes.
When the atoms in a flame reach their high energy levels, they are attracted to each other and to the oxygen that is surrounding them. This interaction is what keeps the chemical reaction going — releasing energy as they continue to vibrate and release gasses.
Because the gases are hotter than air, they are less dense, so they rise. This is why we see a flame is not round, but rather pointed at the top. The gases are also constantly combining with oxygen to make more gasses, which is why we continue to see the flame.
This type of chemical reaction is what we use to create electricity in power stations. The chemical energy from the burning fuel is converted into mechanical work by steaming turbines that spin an electric generator, producing electricity. This is a great example of how fire can help convert other types of fossil fuels, such as coal or petroleum, into electrical energy.