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Darrian Bell
September 19, 2011
Flame Tests
Introduction/Purpose:
In this experiment, I performed a flame test on seven different metallic ions using
a lab burner. Also, I performed a flame test on two unknown substances. The theory of
the experiment is that the color of an electron represents the energy level of the
electron. Each electron energy level has a different color, although colors may be
similar. The color depends on the energy level change that takes place. If it has a high
energy level, it will have a different color flame than if the electron has a lower energy
level.
Problem: What colors are characteristic of particular metallic ions in a flame test?
Hypothesis: The ions are represented by the simple colors of the rainbow, or somewhat
similar. (Different shades.) The colors at the top of the rainbow will be the electrons
with least energy and the ones at the bottom will be the electrons with the highest
energy.
Experiment:
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Independent Variable: metallic ions
Dependent Variable: color
Constant Variable: same flame height & temp.
Control Group: no solution on the loop
Experimental Group: unknown solutions
Procedures:
1. Gather materials and read the lab information.
2. Light the burner and adjust the flame to low.
3. Before each test, clean the wire by dipping it in a disinfecting solution. Then, dip
the loop into a solution filled beaker and hold the loop on the flame until a color
appears. (May have to repeat if color doesn’t appear in a few seconds.)
4. Record your results.
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5. Repeat experiment on the unknown solutions.
6. Turn off the burner and clean up your area.
Data:
Flame Tests of Known Solutions
Salt Solution
Ba(NO3)2
Cu(NO3)2
LiNO3
KNO3
NaCl
Ca(NO3)2
Sr(NO3)2
Color
Yellow
green
Rose red- orange
Pink- purple
Bright orange
Red orange
Hot pink
Flame Tests of Unknown Solutions
Unknown
D1
D2
4
3
Color
Pink- purple
Bright orange
Analysis:
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What metallic ions are present in the unknown solutions?
K: D1, & Na: D2
Summarize the process that produces the colors seen in the flame tests.
Electrons are absorbing energy from the flame, and then they release that energy
and the color of the flame changes.
What is the relationship of the colors you saw and the lines of the
electromagnetic spectrum produced by the metals?
More energy- blues and purples. Less energy- red and orange. Middle energyyellow and green
Which element gave the most easily identified color?
Cu(NO3)2
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5. Which element was hardest to identify?
 LiNO3
6. Do you think that flame tests are valuable for detecting metal ions present in a
mixture of metal ions? Explain.
 Yes, they are similar to fingerprints because none are the same.
7. Why are paper logs that are burned in fireplaces soaked in solutions of metal
salts? Which metals (colors) would be most desirable?
 To see pretty colors; rose-red and orange.
8.
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List the metal ions from least to highest energy.
LiNO3
Ca(NO3)2
NaCl
Ba(NO3)2
Cu(NO3)2
Sr(NO3)2
KNO3
Conclusion:
By concluding the experiment, the metallic ions tested in the flame test were
rated by the color of the flame according to the energy of the electron. To determine
the identity of the unknown electrons we compared the unknown flames to the known
flames to see which were similar. The colors at the top of the rainbow will be the
electrons with least energy and the ones at the bottom will be the electrons with the
highest energy.