Featured LAB: Flame Tests

Featured LAB

83

Flame Tests

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SAFETY
Instructions

You will be working with flames and chemicals today.

Wear safety goggles.

Roll up long sleeves, tuck in loose clothing, and tie back long hair.

Know the location of the eye wash, fire blanket, and fire extinguisher.

Purpose

To identify metal atoms in a variety of compounds by using a flame test and to provide evidence for the presence of certain atoms within compounds.

Materials

  • Bunsen burner

  • set of tongs

  • copper wire

  • penny

  • set of 11 solutions: sodium carbonate, Na2CO3; potassium nitrate, KNO3; copper (II) nitrate, Cu(NO3)2; strontium nitrate, Sr(NO3)2; potassium chloride, KCl; sodium chloride, NaCl; copper (II) sulfate, CuSO4; strontium chloride, SrCl2; sodium nitrate, NaNO3; copper (II) chloride, CuCl2; potassium sulfate, K2SO4

  • 11 pieces of nichrome wire, each with a loop at one end

Procedure and Observations

  1. For each solution, follow these steps and record your observations.

    • Place the loop end of the nichrome wire into the solution.

    • Place the loop end with the solution on it into the flame.

    • Record the color of the flame in your table.

    • Place the nichrome wire back in the correct solution.

  2. Using tongs, place the penny and the copper wire into the flame one at a time and observe the results.

Analysis

  1. Group the substances based on the color of flame produced. What patterns do you notice in the groupings?

  2. Making Sense Can a flame test be used to identify a metal atom in a compound? Why or why not? What about a nonmetal atom?

  3. If You Finish Early Copper oxide, CuO, is a black solid. It doesn’t look at all like the element copper. What color flame would it produce? Draw a model of copper oxide to explain the color of the flame that it would produce.