Flame Test Lab
Name _____________________________ Pd ____
Problem
To determine the metal in the unknown solution. You must first perform a flame test with a variety of
standard solutions of different metal compounds. Then, you will perform a flame test with the unknown
solution to see if it matches any of the solutions you’ve used as standards.
Background
After electrons of an atom absorb energy to move from their ground state to an excited state, they will
eventually fall back to their ground state. When they do this, the energy they absorbed will be reemitted in the form of light. Because each atom has a unique structure and arrangement of electrons,
each atom emits a unique type of light. This is how the chemical test known as a flame test works. The
atoms are excited by being placed within a flame. As they re-emit the energy in the form of light, the
color of the flame changes. For most metals, these changes are easily visible. However, even a tiny
speck of another substance can interfere with identification of the true color for a test, so be sure to
keep the equipment very clean, and perform multiple trials to check your work.
Materials
1. Bunsen burner
2. spot plate – ceramic or plastic
3. wooden splint
4. 8x Pipet containing each of the known and unknown solutions
A. sodium sulfate
F. lithium chloride
B. strontium chloride
G. barium chloride
C. copper (II) sulfate
H. potassium nitrate
D. calcium chloride
I. lead (II) nitrate
E. potassium sulfate
J. unknown substance
5. small beaker
Procedures
1. Gather all the materials.
2. Light the Bunsen burner, with the supervision of Mrs. Akana.
3. Fill the small beaker halfway with water.
4. Put 3-5 drops of sodium sulfate (labeled A) in the first well of the spot plate.
5. Take a wooden splint, dip it in the first well, and then place it into the flame. Observe the flame
color. Take the wooden splint out of the fire once it has been burnt at the halfway point, to avoid
burning your fingers. Immediately put the light wooden splint into the small beaker filled with water,
to avoid a fire.
6. Record your observations in the Data Table.
7. Repeat steps 4-6 for all the chemicals listed above, including the unknown substance.
8. Pour the left over solution in a marked waste container.
9. Wash and return all equipment to the designated areas. Wipe down the lab table and throw away
trash.
10. Wash your hands.
Data Table
Pipet
A
Chemical Solution
Sodium sulfate
B
Strontium chloride
C
Copper (II) sulfate
D
Calcium chloride
E
Potassium sulfate
F
Lithium chloride
G
Barium chloride
H
Potassium nitrate
I
Lead (II) nitrate
J
Unknown
Flame Color
Conclusion Questions
1. What is the identity of the metal in the unknown solution? Explain how you came to that decision.
2. Is it the metal or the nonmetal that gives the chemical its flame color?
3. A student performed flame tests on several unknowns and observed that they were all shades of red.
What should she do to correctly identify these substances? Explain you answer.
4. During a flood, the labels from three bottles of chemicals were lost. The unlabeled bottles of white
solids were known to contain the following: strontium nitrate, ammonium carbonate, and potassium
sulfate. Explain how you could easily test the substances and relabel these three bottles. (Hint:
ammonium ion does not provide a distinctive color when flame-tested.)
5. Some stores sell jars of “fireplace crystals.” When sprinkled on a log, they turn the flames colors,
such as blue, red, green, and violet. Explain how the crystals can change the flame color (discuss the
behavior of electrons). What ingredients do you expect them to contain?