Question

What is a flame test used for?

Answer 1

The flame test is used to visually determine the identity of an unknown metal or metalloid ion based on the characteristic color the salt turns the flame of a Bunsen burner. The heat of the flame excites the electrons of the metal ions, causing them to emit visible light.

Complete answer:
A flame test is an analytical procedure used in the qualitative analysis of the compounds. It helps to determine the identity or possible identity of a metal or metalloid ion found in an ionic compound. It is used to observe and analyze the presence of certain elements in the given compounds of salts.
Procedure:
While performing the test, the sample of the element or compound is introduced to a hot non-luminous flame. Then the colour of the flame is observed. During the test, when the sample is heated its atoms evaporate and because they are hot they emit light when they come in contact with flame. Usually the compounds that are volatile give a better result. It is preferred to use different flames to avoid wrong data due to "contaminated" flames, or occasionally to verify the accuracy of the color.
The flame tests are easy to perform and can be carried out with the basic equipment found in most chemistry laboratories. However, the range of elements positively detectable under these conditions is small, as the test relies on the subjective experience of the experimenter rather than any objective measurements.
The flame test is not distinctive as multiple variables are included in it. Generally, only a single tool used is available to observe the elements present in a compound.

Note:
There are certain precautions that need to be taken while performing the test. Make sure that all the flammable substances are removed from the area of demonstration. Safety glasses and hand gloves should be used. Use water beakers to make sure the splinters are off.