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Lab #8: Flame Tests Chemistry 10 points LAB SCHEDULED FOR THURSDAY, NOVEMBER 19, 2015 Goal: The goal of this lab is to first observe several chemical compounds in a flame and then choose which chemicals would be the best choice for colored-flame birthday candles. Research: (answer in complete sentences in your lab book; please don’t write the questions!) 1) Read through the background and procedure. Is this a qualitative or quantitative lab? Explain your answer. 2) Read through the procedure. Does this lab involve physical changes, chemical changes, or nuclear changes? Explain your answer. (You are allowed to choose more than one.) 3) What happens to electrons during a flame test? Include a small diagram. 4) In this lab, we will use many aqueous solutions. (a) What is a solution? (b) What is a solute? (c) What is a solvent? (d) What does the word aqueous mean? Background and Introduction (don’t write in your lab book): Several companies now make colored-flame birthday candles, where the flames are not just the traditional yellow/orange. In this lab, you will experiment with several chemical compounds that may (or may not) produce colored flames and then choose which would be the best choice for each color (red, orange, yellow, green, blue, violet) in a set of colored-flame birthday candles. Some candle-making companies also market their candles as natural and/or non-toxic, important for use near/in food and for marketing purposes. When making your choice, the hazards of each chemical should also be considered. (We will ignore the costs of each chemical at this point.) Some of the chemicals will be available in aqueous solution form. Others will be available in solid powder form. The form of the chemical that gives the best color should also be considered. A note of caution: Flame tests are easily contaminated. Make sure to use a clean Q-tip for each observation and put it in the waste container so no one else uses it accidentally. Materials: (DON’T write in your lab book) 1 forceps 1 sparker 4 small watchglasses 12 Q-Tips 2 mL calcium nitrate solution [Ca(NO3)2] 2 mL cupric chloride solution (CuCl2) 2 mL cupric sulfate solution (CuSO4) 2 mL lithium chloride solution (LiCl) 2 mL sodium chloride solution (NaCl) 1 permanent marker 1 Bunsen burner 1 heat resistant pad 1 250 mL beaker 2 mL barium nitrate solution [Ba(NO3)2] 0.1 g solid cupric chloride (CuCl2) 0.1 g solid sodium chloride (NaCl) 0.1 g solid sucrose (sugar) (C12H22O11) 2 mL potassium sulfate solution (K2SO4) 2 mL strontium nitrate solution [Sr(NO3)2] Hazards: (List the safety contract and one complete sentence of hazards for each of the chemicals being used. That’s at least 9 sentences!) Procedure: (DON’T write in your lab book) 1. Make a table in your lab book with room for each chemical’s name, its appearance, and its flame color/observation. 2. Label the beaker H2O with the permanent marker. 3. Fill the beaker approximately half way with tap water. 4. Get set-up approval from the teacher. 5. Light the Bunsen burner. 6. Record an initial observation of the chemical at the station. 7. Dip a Q-Tip into the chemical. (If it is a solid, rub the Q-Tip onto the watchglass to pick up some of the chemical.) 8. Put the Q-Tip in the hottest part of the flame. 9. Observe the color of the flame. 10. Extinguish the Q-Tip in the beaker of tap water. 11. Place the extinguished Q-Tip in the waste container at the station. 12. Repeat steps 6-11 for the other eleven chemicals. 13. Clean up! a) throw wet Q-tips from the last station away b) pour extinguished Q-tip water down drain Post-Lab (Please answer in complete sentences. Please do NOT write the questions!): 1) Review your data and hazards. Which chemical would you propose using to make the red, orange, yellow, green, blue, and violet flames for the set of birthday candles? 2) Which did you find produced the best colors: solids or solutions? Why do you think that form produced better colors? 3) How did using Q-Tips affect the color of the flames? How could this lab be done without the Q-Tips? 4) Are there any colors that you did not see during the lab? If so, propose how you would go about finding a chemical that would produce that color of flame. 5) Were there any chemicals that did not produce a colored flame? 6) What part of the flame produced the best colors? Include a diagram with your answer. 7) Propose two new tests/experiments/labs/questions that you could investigate with the skills and equipment from this lab.