To find answers for many different versions of the flame test lab, read descriptions of the flame test on general chemistry websites such as Creative Chemistry and Chemguide. In the flame test experiment, students moisten a wire with hydrochloric acid, dip it into a metal salt, and place it in a flame. The flame changes color, with the exact color depending on the identity of the metal cation in the salt.
Because different metals produce different colors, the flame test is useful for distinguishing between salts that look similar. For example, calcium and potassium salts both appear white. However, calcium salts emit red light in a flame, while potassium salts emit violet light.
The flame test experiment is often used to teach about electronic structure. The colors emitted during the experiment are caused by the absorption and release of energy by electrons. When a metal ion is heated, its valence electrons absorb energy and move to a higher energy level. When the electrons return to their original energy level, they release the extra energy as light. The color of the light depends on the amount of energy released, which is determined by the difference between energy levels. For example, red light has lower energy than violet light, so an element that emits red light has a smaller distance between energy levels than an element that emits violet light.