SCH4C
Name: __________________________
Lab 2: Identifying an Element with Flame Tests
Purpose:
To identify a metallic element in an ionic compound using a flame test.
Background:
When electrons in an atom are excited by heat or electricity, they gain energy and move to higher orbits
(energy levels). When an electron drops back down, it releases the energy in the form of light. Since
the number and arrangement of electrons around each element is different, each element produces a
characteristic colour related to the unique line spectrum.
In this lab, you will use a technique of qualitative analysis called a flame test. Different ionic
compounds will be heated to observe the colour of light they produce Using these results, you will then
identify the metallic element present in an unknown compound.
Materials:
goggles
nichrome test wire
2 test tubes
test tube rack
Bunsen burner
5 mL dilute hydrochloric acid
sodium nitrate solid (NaNO3 (s))
sodium chloride solid (NaCl (s))
calcium chloride solid (CaCl2 (s))
strontium chloride solid (SrCl2(s))
lithium chloride solid (LiCl(s))
potassium chloride solid (KCl(s))
copper (II) chloride solid (CuCl2(s))
unidentified ionic compound
Safety:


Hydrochloric acid is corrosive. Use goggles and avoid inhaling fumes.
Use caution when using a Bunsen burner and hot equipment.
Procedure:
1. Read the procedure and create an observation table.
2. Obtain a test tube containing about 5 mL hydrochloric acid. Place in a test tube rack.
3. Light a Bunsen burner and adjust it to produce a blue flame.
4. To clean the nichrome wire, dip it into the hydrochloric acid solution and then hold the wire In the
flame (see diagram). Repeat this step until the wire adds no colour to the flame.
5. Obtain a sample of solid sodium nitrate. Pick up a small amount of the solid with the loop of the
nichrome test wire. Hold the end of the wire in the flame. Record your observations.
6. Clean the wire as explained in step 4.
7. Repeat steps 5 and 6 with the remaining solid samples. Remember to clean the wire after each test.
Record your observations.
8. Obtain an unidentified metallic compound. Repeat the flame test and record your results.
9. Dispose of the acid in the Acid/Oxidizer waste bin. Rinse the test tube and clean the bench.
Analysis:
Based on your results, create a flame test identification key to describe the colour produced by various
metals.
Conclusion:
Analyze the observations and write a statement identifying the unidentified metallic element.
Questions:
1. a) What are two possible sources of error in this experiment?
b) How can the procedure be changed to reduce these sources of error?
2. What effect do the non-metal elements in each compound appear to have on the colour of the
flame? Support your answer by referring to the results of the experiment.