Flame test lab

Description: Small amounts of different salts are burned in the flame of a Bunsen burner. When the electrons in the atom reach an excited state, they must release that energy as a characteristic color, which is associated with each metallic ion will be observed and used to identify an unknown salt mixture.

Purpose: To demonstrate that when atoms or ions of certain elements absorb energy, the energy is emitted as a wavelength of light characteristic of that element. Note that the metal ion will be the subject that emits the visible color.

Procedure:

  1. At your lab station, you will find coffee stirrers that have been soaking in water.
  2. Take one of the stirrers and dip it into VERY LITTLE the compound in the weighing boat.
  3. Put into the flame of the burner. Hold the salt in the outer cone of flame and burn to show color.Make sure there is not too much on there because there may be a chance that it will fall off into the Bunsen burner.
  4. Observe the color given off and record it. Many of the metals in the compounds will give off a yellow color at beginning or at the end of the trial. You are looking for a flash of an additional color. If the flame only shows yellow, then record that as the color. Try each one several times. One or more may show no, or very little color. Choose “no color” for these compounds. You have the choice of the following colors to record:

Red

Crimson

Orange-Yellow

Green-Yellow

Green

Blue-Green

Violet

No color

Compound / Element emitting color / Symbol and Charge of Cation / Color
Barium chloride / Ba 2+
Calcium chloride
Copper (II) chloride
Lithium Chloride
Potassium Chloride
Sodium Chloride
Strontium Chloride
Cobalt (II) Chloride
unknown

Questions:

1) In your own words, explain why different elements give off different colors when heated.

2) Do you think that this method of identifying unknowns would be effective for identifying any unknown element? Explain why or why not.

3) Using what you learned, explain how a white light bulb works.

4) Is it possible for an element to give off light that we cannot see? Explain why or why not.

5) Give the electron configuration for sodium and calcium.

Conclusion: