“Hmmm… What IS this chemical? Well, let’s just burn it!”
Imagine that you are faced with an unknown chemical, a salt of some sort. This kind of situation won’t be common in a household, but it could happen in a chemistry laboratory with hundreds of chemicals, where maybe a student has misplaced the label. (A lab fact: students usually get the blame.)
One of the ways you can solve the mystery is through a flame test. Take a small scoop of the salt on a tip of a spatula and bring it over a bunsen burner. Each element gives a unique color when it burns. (Why? Find out here.) So, you’ll have an idea what element is present based on the color of the resulting flame. For example, sodium burns at a characteristic intense yellow (center of the photo above). This won’t tell you if it’s sodium chloride, sodium carbonate, or sodium nitrate, but at least you know it’s not potassium chloride! (Potassium would turn a flame lilac.) Check out a table of elements and their flame colors on Wikipedia.
As you watch fireworks, it might be fun to guess which elements are present. Deep orange colors, for example, are often made using salts of calcium, whose signature flame color is brick red.
You can try flame test at home, but be careful! It’s probably the best if you can do it at school; consult a chemistry teacher. Have fun!