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LAB: The SAFE and PROPER Use of a Bunsen Burner A Bunsen burner is a valuable tool used in science. However before we can use this tool, we must understand how it works. The purpose of this lab is to learn how to SAFELY and PROPERLY use a Bunsen burner. In addition, you will find the coolest and hottest parts of a correctly adjusted BLUE flame. Lab Safety when using a Bunsen burner: 1. Always wear Eye Protection 2. Never use a Bunsen burner near flammable liquids or materials 3. Tie back long hair 4. Never have loose clothing near the flame 5. Never heat a test tube or container that has a lid, stopper or cap 6. Only heat items the teacher says are OK to heat IN CASE OF AN EMERGENCY…TURN OFF THE GAS! Figure 1: Anatomy of a Bunsen Burner Proper Use of the Bunsen Burner: 1. At your desk there is a sliver-colored gas outlet. The outlet is ON when the handle points toward the nozzle and it is OFF when the handle is perpendicular to the nozzle. This outlet should be OFF before and after you use the Bunsen burner. 2. Check to see if the rubber hose is attached tightly to the Bunsen burner. Then attach the rubber hose to the nozzle of the gas outlet. 3. The gas flow control on the burner is a knob underneath the burner. This knob is OFF when it is screwed into the base of the burner. Unscrewing the knob will let gas flow. Make sure this knob is in the OFF position at this point. 4. The flow of air to the burner is controlled by the position of the burner barrel. Adding air makes the flame hotter. Turning the tube or barrel counterclockwise allows more air to be mixed with the gas making a hot BLUE flame. For now, turn the tube clockwise and close it so no air will mix with the gas. Gas = ORANGE/YELLOW Warm Flame Gas + Air = BLUE Hot Flame 5. Turn ON the Gas outlet by pointing the handle toward the end of the nozzle. DO NOT use the outlet to change the amount of gas going to the Bunsen burner. 6. Light a match and hold it next to the top edge of the burner. Turn the gas knob clockwise on the bottom of the Bunsen burner until the burner lights (about 2 turns). Light the Bunsen burner. The flame should be ORANGE/YELLOW at this point. 7. Change the height of the flame by turning the gas flow control at the bottom of the burner. Turning this knob clockwise will make the flame larger. Turning the gas knob counterclockwise will make the flame smaller. Adjust this knob to give a flame about 3 inches high. 8. Now add air by turning the tube/barrel of the burner. If you add too much air, the flame will make a hissing noise and may even go out. If you don’t add enough air, then your flame will not be hot enough for most of the labs in this class. Add just enough air to give a DARK BLUE flame that burns quietly with an inner LIGHT BLUE cone. 9. Put a wire in the BLUE Bunsen burner flame to find the cool, warm, and hot parts of the BLUE flame. 10. When you have created “the perfect flame” (as judged by your very wise teacher), you should perform the following temperature test: Pass a wire through the Bunsen burner flame to find the cool, warm, and hot regions of the flame. The wire will turn bright ORANGE or RED in the hottest parts of the flame. You will draw and color the flame of your burner and label the hottest and the coolest parts of the flame. A systematic approach to completing this task may be to hold the wire at one-centimeter intervals of the flame, starting at the base and working your way slowly to the top. After drawing, coloring and labeling your flame, answer the questions below. When you are finished practicing the SAFE and PROPER use of your burner, turn OFF the gas outlet and disconnect the hose from the gas intake. Questions: 1. How can you tell when there is not enough air mixing with the gas in the Bunsen burner? How do you adjust the burner to fix this situation? 2. How can you tell if there is too much air mixing with the gas? How do you fix this situation? 3. What would happen if you held a closed test tube over a Bunsen burner flame? Why would this happen? 4. If you needed to heat some glass tubing to bend it, in what part of the flame would you put the tubing? 5. List at least four things that this student doing wrong.
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