Peter Jeschofnig, Ph.D. Version 42-0160-00-01
Lab RepoRt assistant
This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.
The color of the flame is expected to be as follows:
Metallic ion Flame color
Sodium Na+ Yellow/Bright Orange
Strontium Sr2+ Red
Potassium K+ Light Purple
Barium Ba2+ Green Copper Cu2+ Green
Lithium Li+ Red
Calcium Ca2+ Orange
A. All chemical used in this test are binary compounds. What portion of the periodic table is responsible for the color observed?
The Metals portion
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?
Sodium is likely the source of the yellow flame, as it turned yellow/orange in the test.
C. What problems might be associated with using flame color for identification purposes?
The cotton and/or well plate could have been contaminated.
Also, some of the colors look very similar and may be hard to discern.
If the Q-tip/cottoned toothpick was not soaked enough, the flame would burn that instead of the compound, thus swaying the results.
D. Explain how the observed colors are produced
As the substance heats up, the electrons gain energy from the flame to move to a higher level of energy. At this higher energy level, the electrons become unstable and start to come back down to the “ground state” (lower energy levels). As this happens, the electrons in the substance release a certain amount of energy, which we see as a color