Color of the Stars: Flame Test Name Light sources in the night sky include stars, galaxies, nebulae, and meteors. In addition to visible light, there are also invisible electromagnetic radiation signals reaching our atmosphere, such as ultraviolet light, infrared waves, microwaves, x-rays, and radio waves. Astrophysicists use this information to work out the structure of the universe, and discover how it behaves. Every chemical element that any cosmic body is made of has its own spectral “fingerprint,” a pattern of light across the visible spectrum that is evident in chemical flame tests. Most of us are familiar with the rainbow of colored light that appears when sunlight is separated into its constituent wavelengths by a prism. When prisms are used to analyze the colors of light from the stars, information about the chemistry of these cosmic bodies is revealed. Materials required: Nichrome wire wand Bunsen Burner Lighter/Sparker Test tubes containing: Manganese chloride Lithium chloride Strontium chloride Calcium chloride Cobalt chloride Goggles Diffraction grating Potassium chloride Copper chloride Sodium chloride Barium chloride Procedure: Safety: Wear goggles at all times. If you want to remove them to write on your lab, you may sit at a table in the center of the room. When you sit down, you may remove the goggles, but before moving back to the lab table, put the goggles back on. Pull back hair, no loose clothing, close-toed shoes. Use professional lab practices. It is very important that you do not mix up the nichrome wires, or switch cork stoppers on test tubes! WATCH DEMO BEFORE YOU BEGIN! 1. Work in teams of three-four. All members are held accountable for professional lab practice. There are Four team jobs, all which must be assigned to a team member: a. The General / Materials – reads the directions out loud and makes sure the group is on task. Handles materials during and between flame tests. Name of Group Member_______________________________ b. Flame Tester – sets the Bunsen burner at the “double blue cone” and puts the nichrome wire into the Bunsen burner to test the flame. Name of Group Member_______________________________ c. Color recorder – observes the color of the flame and records it on the lab paper. Name of Group Member_______________________________ d. Videographer – sets up and records video using their phone with the diffraction grating taped over the camera. Also in charge of taking screenshots of the video and editing the chemical names. Name of Group Member_______________________________ 2. Have the videographer tape the diffraction grating on the corner of the square so that the clear part is covering the front of their camera. DO NOT TOUCH THE CLEAR PART, YOU WILL RUIN THE DIFFRACTION GRATING! Use the ring stand and ring clamp to provide a place for the phone to be propped up that can record the flame tests. 3. At each table there are will be one sample, one bare nichrome wire not in the tube, and one Bunsen burner. Start the burner as you have learned to do and obtain a blue flame with an inner blue cone. 4. Take the SEPARATE nichrome wire, the one NOT in the test tube, and place it in the blue flame. Notice its color when it becomes red hot. This is not the color of the flame you are looking for. The flame to observe is the one obtained just as you place it in the flame. a. Meanwhile, the videographer should angle their camera to the side of the flame, where the diffracted light can be seen. Leave your camera pointed here for the duration of the lab! 5. It is now time to test your first chemical! Using the nichrome wire in the test tube with the solution of the compound, then quickly place the wire in the flame and observe its color. Have the color recorder write down the color and any observations on the table provided with the lab. Cool the wire off with the provided water test tube before placing the wire back in the chemical. Test each chemical no more than three times. 6. When testing is complete, rotate with the other lab group next to you. Stations Calcium (0.5M CaCl) Sodium (0.5M NaCl) Barium (0.5M BaCl) Lithium (0.5M LiCl) Copper (0.5M CuCl) Cobalt (0.5M CoCl) Manganese (0.5M MnCl) Potassium (0.5M KCl) Strontium (0.5M SrCl) UNKNOWN 1 UNKNOWN 2 Observed Flame Color Color of Emission Lines Flame Test Lab Analysis: Name________________ Red Orange Yellow Green Blue Purple 1. List the elements observed in this lab from the shortest color emmited wavelength to the longest color emitted wavelength. (tip: list by elements, and in parentheses include their color.) 2. Do you think we can use the flame test to determine the identity of unknowns in a star? Why or why not? 3. Why do different chemicals emit different colors of light? 4. Why do you think the chemicals have to be heated in the flame first before the colored light is emitted? 5. Colorful light emissions are applicable to everyday life. Where else have you observed colorful light emissions? Are these light emission applications related? Explain. 6. Research some information about the origin of fireworks. Explain how they are made, what chemicals are used, what color they burn and their uses. Use at least 3 complete sentences. In the coming days, you and your group will also be responsible for putting together a google slides presentation of all 9 samples and the 2 unknowns from the videographer’s diffraction grating footage. This will fall into the lab score for the flame test lab.