Flame Test Lab
BACKGROUND
The characteristic light emitted by each individual atom is the basis for the chemical test
known as a flame test. To identify an unknown atom, you must first determine the
characteristic colors produced by different atoms. You will do this by performing a flame test
on a variety of standard solutions of metal compounds. Then you will perform a flame test
with an unknown sample to see if it matches any of the standard solutions. The presence of
even a speck of another substance can interfere with the identification of the true color of a
particular type of atom, so be sure to keep your equipment very clean and perform multiple
trials to check your work.
Sensitivity in qualitative tests is the ability to distinguish between different samples based on
the result of the test alone. In this test, the physical property of color should be used to
determine exactly which metal ion is present in the unknown. After reading the procedures
for this experiment, write a hypothesis about the colors you expect or the sensitivity of the
test.
SAFETY
Always wear safety goggles and a lab apron to protect your eyes and clothing. If you get a
chemical in your eyes, immediately flush the chemical out at the eyewash station while
calling to your teacher. Know the locations of the emergency lab shower and eyewash station
and the procedures for using them. Do not touch any chemicals. If you get a chemical on
your skin or clothing, wash the chemical off at the sink while calling to
your teacher. Do not taste any chemicals or items used in the laboratory.
OBJECTIVES
• Identify a set of flame-test color standards for selected metal ions.
• Relate the colors of a flame test to the behavior of excited electrons in a metal ion.
• Identify an unknown metal ion by using a flame test.
MATERIALS
• De-ionized water
• 250 mL beaker
• Bunsen burner and related equipment
• water-soaked wooden splints
• CaCl2 (Ca2+)
• Ba(NO3)2 or BaCl2
• KCl
• LiCl
• CuCl2
• NaCl
• SrCl2
• 2 unknown solution
Rev. 1
Flame Test Lab Report
Purpose
To distinguish metal ions by the colors they produce in a flame test.
PROCEDURE
l. Clean your splint between trials by rinsing it with distilled water over the beaker.
2. Make a data table like the one below. Make one row for each sample in addition to a row
for water alone.
3. Dip the soaked splint into the solid substance, then hold it in the bunsen burner flame.
Observe the specific flame color and record it in your data table. Repeat the test and
record the results for trial 2 in the data table.
4. Make sure your splint is out before leaving your lab table.
5. Rinse splints and allow them to cool fully before disposing.
6. Leave your lab table clean.
Sample Data table: Make your own Data Table with one row per substance.
Substance
Color
Water (control)
CaCl2 (Ca2+)
NaCl (Na+)
RESULTS AND ANALYSIS
Summarize your results, including your data table.
Answer the following questions using complete sentences.
1. Was there a difference in the results of NaCl vs. CaCl2?
2. What ions are present in your unknown solution? “Unknown # 1 contains ________ions.
Unknown #2 contains _____ ions.”
3. Sensitivity of a test indicates how well it can be used to tell the difference between
substances. A very sensitive test will differentiate two different samples so that you have
no doubt about the differences between the two.
How would you characterize a flame test with respect to its sensitivity? What difficulties
could there be when identifying ions by the flame test?
CONCLUSION
Explain why different colors of light are seen with different elements AND make a statement
about the usefulness of a flame test in identifying elements. You must use the words
“electron” and “energy” in your explanation.
Rev. 1