Identification of Metallic Ions
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:
A. All chemical used in this test are binary compounds. What portion of the periodic table is responsible for the color observed? The 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? Barium is most likely responsible. It burned yellow over the flame.
C. What problems might be associated with using flame color for identification purposes? Some of the colors can look similar. Also, if you don’t have enough of the substance on the Q-tip, the flame will start to burn that instead and will turn a different color.
D. Explain how the observed colors are produced.
As the substances are heated, the electrons move to higher energy levels by absorbing the heat. This state is unstable and the electrons tend to return to their ground state and release the absorbed heat energy in the form of electromagnetic energy. A portion of this energy being released is in the visible light region.
Metallic Ion Flame Colors
Sodium Na+ Orange
Strontium Sr2+ Pink/Red
Potassium K+ Light blue/Purple
Barium Ba2+ Yellow
Copper Cu2+ Green
Lithium Li+ Pink
Calcium Ca2+ Pink/Orange
Unknown Pink/Red - Strontium