UP IN FLAMES
EMISSION SPECTROSCOPY LAB
SAFETY
Follow appropriate safety procedures when operating the burners. Tie back long hair and secure loose
clothing.
Many of the salts used in this experiment are toxic. Be sure to wash hands thoroughly after coming into
contact with any of the substances.
PROCEDURE
Flame Tests of Metal Ions
1. In this segment of the lab, you will be rotating through eight (8) different stations in a clockwise direction.
You will have 2-3 minutes at each station.
2. If the burner is not lit, follow the appropriate procedures for lighting the burner. Pick up a correctly
labeled nichrome wire loop.
3. Dip the wire loop into the beaker of distilled water. Then, dip the wire loop into beaker of metal salt
crystals so that a few crystals adhere to the loop. Don't pick up too many crystals or they will make a
mess!
4. Place the wire loop in the burner flame. Observe the color produced and record it in your lab notebook.
Watch carefully because some colors will not last long. Be as descriptive as possible (e.g. red-orange
instead of orange).
5. Rotate to the next station. DO NOT LEAVE A FLAME UNATTENDED. If another group is ready to use
your station, you may leave the flame burning. Otherwise, extinguish the flame by turning off the gas
before leaving the station.
6. Repeat steps 4 - 7 until you have observed all seven metal salts and the unknown.
OBSERVATIONS
Record your observations as directed in the procedure. Use a ruler if you choose to make a table. Record
the metal salts in the following order:
1.
2.
3.
4.
Lithium nitrate, LiNO3
Sodium nitrate, NaNO3
Potassium nitrate, KNO3
Calcium nitrate, Ca(NO3)2
5.
6.
7.
8.
Strontium chloride, SrCl2
Barium nitrate, Ba(NO3)2
Copper(II) nitrate, Cu(NO3)2
Unknown
ANALYSIS
1. How does the flame test provide support for quantized energy levels? Explain your answer.
2. What particles are found in the chemicals that may be responsible for the production of
colored light?
3. Why do different chemicals emit different colors of light?
4. Why do you think the chemicals have to be heated in the flame first before the colored light
is emitted?
5. Colorful light emissions are applicable to everyday life. Where else have you observed
colorful light emissions. Are these light emission applications related? Explain.
6. What is the characteristic flame color for sodium, lithium, barium, copper, strontium, and
calcium? Explain why.
Emission Spectroscopy Lab
CHEM
7. When the spectroscope was used to view the flame, explain why different colorful emission
lines were observed for the elements.
8. When performing this flame test, were you testing for the chloride in the compounds or were
you testing for a metal? Explain.
9. If the unknown was a combination of lithium chloride and strontium chloride, would you be
able to identify the elements present in the mixture? Explain.
10. Identify the two unknown compounds and explain HOW you figured them out. (use your
observations).
11. Explain how colors are produced by the two methods used in this lab. Include the terms
“ground state,” “excited state,” and “photon” in your explanation.
12. As a forensic scientist, you are given the task of identifying an unknown substance found at
a crime scene. Which method do you think would provide more reliable results – a flame
test or the emission spectrum? Explain.
Emission Spectroscopy Lab
CHEM
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