THE IDENTIFICATION LAB
(Lab Guidelines: 1, 2, 3, 4, 5&6 [attach handout], 7, 12)
Purpose: To identify an unknown metallic halide solution using data from known metallic halide solutions.
Introductory Material: Metallic halides, cations, anions, basic formula writing and naming, precipitate
formation.
Materials: Known metallic halide solutions (0.10 M), silver nitrate (0.10 M), sodium thiosulfate (0.50 M),
ammonia (6.0 M), spot plate, Bunsen burner, nichrome wire, concentrated HCl
Procedure:
DAY 1
Plan a procedure to test whether or not the known metallic halides form precipitates when mixed with silver
nitrate. Use 3 drops of each solution.
If a precipitate does form, add ammonia and note whether or not the precipitate dissipates. “Jiggle” the spot
plate to assure complete stirring has taken place.
If ammonia causes no change, add sodium thiosulfate, and note whether or not the precipitate dissipates.
Compare your results to other groups to make sure there is consensus in the class!
Next, you will need to perform all of the above steps with your unknown metallic halide solutions.
Remember to note the unknown letter in your data.
Something to think about: Look at your data and determine whether the above tests tell you more about the
metal ion present or about the halide ion that is present.
DAY 2
Note the proper procedure for conducting a flame test on the halides of sodium, lithium, potassium, copper,
barium, and calcium.
Now perform a flame test on your unknown metallic halide solutions. Does this test tell you more about the
metal ion present or about the halide ion that is present in your unknown?
Data: Create an appropriate data table to chart precipitate formation, dissipation, and flame test results.
Conclusion:
Discuss how you accomplished the purposes of the lab. Also include the following!
1. Identify your unknown – the cation and the anion, and the formula of the compound.
At the beginning of your conclusion section, please include a box with the unknown letters,
cation present, anion present and formula of the compound.
2. Describe in detail how you know what it is. Refer to procedure and data.
3. List at least three new chemical concepts you learned in this lab.