Name:
Date:
Identifying metal compounds using a flame test
Purpose:
To identify the metal contained in a number of different metal compounds,
using a flame test.
Hypothesis:
When a metal is burned in the flame, it's electrons will be "excited" and
jump to higher energy levels. When these electrons drop back to their
ground state, a specific colour of light will be emitted. This colour can be
used to identify the metal.
Materials:
1.
2.
3.
4.
5.
Bunsen burner
Wooden splints various dilute solutions of metal compounds
matches
Obtain dilute solutions of metal compounds in labeled 50 ml beakers.
Place a wooden splint in each of the solutions and let it soak for at least 5 minutes.
For the first solution, place the tip of the soaked splint into the hottest part of the
flame. (This is just above the pale blue zone of the flame).
Note the first flare of colour that is different from the colour of the Bunsen burner
flame. Record these observations in a chart.
Repeat steps 3 and 4 for each of the remaining solutions.
Observations:
Results of flame tests on dilute metal compounds
Name of the compound
Unknown #1
Unknown #2
Chemical
Formula
Metal in compound
Colour of flame
Discussion:
1. Make lists of pairs of solutions that produce exactly the same colour.
2. What is the same about the names of the paired solutions you listed in question #1.
3. Which part of the compound determines the colour of the flame, the metal or the nonmetal?
4. A reddish brown rock was held in a very hot burner flame. The flame appeared emerald
green. What metal is most likely present in the rock?
5. Explain how heating a metal compound causes it to produce coloured light. (i.e.. light
emission by excited electrons).