If you are a “Game of Thrones” series fan like I am, upon looking at the picture of green flame you might think: wildfire. Although you don’t find green-colored fire often in real life, it is possible to make the fire green with a disinfectant or insecticide containing boric acid. So sorry fellow GoT fans, green flame in real life is not wildfire, but ignited boric acid (which is probably a good thing since wildfire is supposed to be extremely dangerous).
In fact, you can color fire many different colors using common household items: table salt (yellow) and various kinds of alcohol including ethanol (blue), to name a couple.
Different chemicals burn in different colors because of their emission spectra. Emission spectrum refers to the emitted photons (light particles) of very specific energy that corresponds to particular wavelengths of light (i.e. particular colors). Each element’s emission spectrum is unique, which lets scientists to use emission spectrum to identify elements in a matter of unknown composition, much alike our fingerprints. This could also come in handy during camping, when the usual monotonous orange-yellow campfire can get a little boring for some people.
But how do atoms get to the higher energy levels? That’s where the fire comes in. Fire supplies the atoms the energy to get the atoms from their ground state to the higher energy levels. And when the atoms are returning to their ground state, you see the characteristic colors for each element.
As for boric acid, boric acid contains the element boron. Boron’s emission spectrum contains blue and orange, which makes green. This green is responsible for the wildfire-like color of the ignited boric acid.
Here’s a slow-motion video showing flames of different colors. But if you want try this in your own backyard, proceed with caution!
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