chemistry lab

Unit 2 Lab: ID Metal Ions

CHEM 1806

Purpose: To identify metal ions by the colors they produce in a flame. The colors and their energies are discussed in this unit. The color is produced by electrons being promoted and then relaxing to the ground state electronic structure. As the electrons move, energy is released and their energy is displayed as photons of light. Depending on the energy, a different color is released. Red is low energy; violet (purple) is high energy.

Materials: Student Supplied – Lighter or matches; 8 paper-stemmed cotton swabs (Q-tips) NOT plastic stemmed ones

LabPaq materials: Burner fuel, Goggles, 24-well plate, Experiment bag “Identification of Metallic Ions”

Procedure:

1. Use the 24-well plate as a chemical holder, as shown to the right.

2. Place about 0.5mL (20 drops) of sodium nitrate in the first well of your well plate.

3. Place the chemical container in the well below the chemical to keep track of which chemical is where.

4. Repeat with the remaining chemicals.

5. Light the burner.

6. Soak a cotton end in the first chemical.

7. Pass the soaked cotton through the flame until there is a change in the flame color. (It might take 6 passes) Move the cotton through fairly rapidly so the cotton doesn’t burn.

8. Record the color change in the data table below.

9. Repeat steps 6-8 with the remaining chemicals, including the unknown.

10. All chemicals can be rinsed down the sink. Extinguish the flame by carefully replacing the cap over the flame.

Data Table: (2pts)

	Sodium Nitrate	Barium Nitrate	Calcium Nitrate	Cupric Nitrate	Lithium Nitrate	Potassium Nitrate	Strontium Nitrate	Unknown
Flame Color

Results and Discussion:

1. (8 pts) Is there a trend in the color of the flame and corresponding placement on the periodic table? Discuss in terms of energy levels and colors observed.

2. (5 pts) What is the identity of your unknown?

3. (5 pts) Insert a picture of your lab set up (try to get a picture of the colored flame too – it isn’t easy!)

4. That’s it. Quick lab.

When you are finished, save the file as LASTNAME_Metals and upload it to the Dropbox for Unit 2 Labs.