Do ALL writing in your SJ!!

SJ #9: Identifying Metals – Flame Tests

Please follow all safety procedures during this lab. Wear goggles to protect your eyes, and be aware of the flame – tie back loose clothing and hair.

Background: Centuries ago, the Chinese discovered what happens when a compound containing a metal is heated to a high temperature. The Chinese put this discovery to a use that has been observed for centuries, and we still find it exciting today. In this activity, you will discover this novel property of solutions of compounds that contain certain metals.

Problem: How can we identify the presence of certain metals in solutions?

Materials:gogglesseveral metal salt solutions (distilled water)

wooden splint pieces*lithium chloride*sodium chloride

forceps*calcium chloride*barium chloride

alcohol burners*potassium chloride*cobalt chloride

little beakers*copper chloride*copper sulfate

cups of water*strontium chloride*unknowns/mixtures

Procedure:

1. Know where all materials are located. Wooden splint pieces should already be soaking in the correct solution.

2. The teacher will light your burners when everyone has goggles on.

3. Using forceps, remove a wood piece from one of the metal solutions in the front of the room. Make sure you know which one you have! Carefully carry it back to your work area and hold it in the flame. Do NOT let the wood touch the wick of the burner.

4. Observe and record your results in the data table.

5. Try not to let the splint catch on fire. Once you have recorded your results, use the beaker at your table to dispose of burnt splints (garbage). Rinse in water if it starts on fire.

6. Rinse your forceps in water before getting a new piece.

7. Repeat steps 3-6 for each metal solution separately, making sure to carefully record what you observe for each solution.

8. Clean up all materials and messes.

9. Answer questions.

Data Table and Questions on back

Metals / Results When Heated / Formula / Metal
val e-
1 / lithium chloride / LiCl
2 / calcium chloride / CaCl2
3 / potassium chloride / KCl
4 / copper chloride / CuCl2 / 2
5 / strontium chloride / SrCl2
6 / sodium chloride / NaCl
7 / barium chloride / BaCl2
8 / cobalt chloride / CoCl2 / 2
9 / copper sulfate / CuSO4 / XXXX
10 / Unknown (1 metal) / XXXX / XXXX
11 / Mixture (2 metals) / XXXX / XXXX

Questions (answer all questions in your SJ).

1. For each metal solution, copy the formula from the board in the data table.

2. For all chloride solutions (#1-8), what is the val e- # of the metal in the compound? Use your periodic table to fill in your answer in the far right column above.

3. Do you notice a pattern between the val e- of each metal compared to the formula? Explain.

4. What groups on the periodic table are the metals in these compounds from?

5. Why is it necessary to rinse the forceps between each test?

6. Compare the colors of the flames to the colors of the solutions. Can you predict flame color based on solution color?

7. How do you think the Chinese used this property of metals?