Exploration 3: flames test-identifying the cationheating different elements in a flame causes electrons in the element to move to higher energy states. when the electrons return to their ground state, the energy is given off in the form of a photon. in many cases, this photon can be observed as visible light. this phenomenon gives each metal a unique colored flame. in this exploration, you will test the flame color of different cations. you will also test the flame color of an unknown metal.

 Here are the colors of the flame tests of some elements:

The color of the flame can also depend on the temperature.

Samples are usually held on a platinum wire repeatedly cleaned with hydrochloric acid to remove traces of previous analytes. It must be tested with different flames, to avoid misinformation due to contaminated flames, or occasionally to verify the accuracy of color. Sometimes nicrom wires are also used.

The flame test is quick and easy to execute, and does not require any equipment that is not generally found in a chemistry laboratory.

Another procedure to do the flame coloring test is to take a small amount of each solution and spread it with the help of a spray or plastic spray on the Bunsen burner flame. A color will be observed throughout the flame.

Explanation:

Under normal conditions the atoms are in the fundamental state, which is the most thermodynamically stable. However, if we heat them it absorbs energy and thus reaches an excited state. This state has a certain energy, which is characteristic of each substance. Atoms that are in an excited state have a tendency to return to the fundamental state, which is energetically more favorable. To do this they must lose energy, for example, in the form of light. Since the possible excited states are peculiar to each element and the fundamental state is always the same, the emitted radiation will also be peculiar to each element and therefore can be used to identify it. This radiation will depend on the difference between the excited states and the fundamental one according to Planck's law:

AE = hv

where

AE = energy difference between excited and fundamental states

h = Planck constant (6.62 10-34 J s)

v = frequency

Therefore, the emission spectrum can be considered as the “fingerprint” of an element. This fact was known since ancient times, before even understanding how it happened, so chemists have used "flame tests" as a simple method of identification.