Flame Tests

Different metal ions produce characteristic flame colors when their solutions are heated in a flame.

1. Label small beakers for each metal salt and prepare about 50 mL of ≈1.0 M aqueous solutions for BaCl2, CaCl2, CuCl2, LiCl, KCl, NaCl, and SrCl2.
2. Soak separate wooden splints in each solution overnight; reserve a water beaker to quench used splints.
3. Set up a Bunsen burner in a clear area and light it with a striker; dim room lights if possible.
4. One at a time, pass a soaked splint slowly through the hottest part of the flame and observe the color; place the used splint in the water beaker.
5. Record the observed color and estimate wavelength or frequency using a visible spectrum chart.
6. For a mixture test, place a copper and a strontium splint in the flame together and identify both colors present.
7. If desired, present two unknown splints for students to identify from their color matches.

Flame Test Colors - Step by Step Science:

The Flame Test Experiment- The Chemistry of Colorful Flames - Chem Camp with Mrs. Newman:

📄 The Flame Test - ACS Institute: https://institute.acs.org/acs-center/lab-safety/education-training/safer-experiments/flame-test.html

• Look at through a spectroscope to filter the individual color bands.
• Spray the solutions onto a flame using a perfume sprayer.

• Wear safety goggles, lab coat or apron, and tie back hair.
• Use only aqueous salt solutions on splints; do not use flammable solvents such as methanol or ethanol.
• Keep flammables away from the burner and maintain a clear workspace.
• Some salts are highly toxic; refer to safety data sheets before use.
• Quench used splints in water and dispose of residues sensibly.

• Which ions produced each flame color, and how can color be used to identify an unknown?
• Using c = λν, convert an observed wavelength to frequency and vice versa; which colors correspond to higher energy photons?
• How do electronic energy levels and electron transitions explain the observed discrete colors?
• How is this safer method different from the traditional rainbow demo that used alcohol fuels on the bench?