Peter Jeschofnig, Ph.D. Version 42-0160-00-01
Purpose: To observe the different flames of alkali and alkaline metals. Procedure: Place a little bit of each element into the well plate. Then you soak a tip of a cotton swab in each solution. Then you place the cotton swab over the Bunsen burner until the flame changes color.
The color of the flame is expected to be as follows:
Metallic ionFlame color
Sodium Na+ Orange
Strontium Sr2+ Dark red
Potassium K+ Purple
A. All chemical used in this test are binary compounds. What portion of the periodic table is responsible for the color observed? Transition Metals.
B. In cooking over an open flame, a yellow flame is often observed when some food is spilled into the flame? What is most likely responsible for the yellow flame color? The chemicals react with the flame.
C. What problems might be associated with using flame color for identification purposes? Many people are color blind or what one color is to one person they see another color.
D. Explain how the observed colors are produced
When a ground state absorbs the heat energy from the flame they become excited and they want to get back to the ground state. As they return to the ground state they release the heat energy they absorb which is seen as visible light.
Conclusion: I learned why different chemicals turn different colors and the chemical process it takes.