Bunsen Burner Lab
Purpose: To learn the parts, function and use of the Bunsen burner
The Bunsen burner is a piece of lab equipment used to perform a variety of procedures requiring heat. It mixes a flammable gas with air to produce a controlled, clean, hot flame.
1. Examine the Bunsen burner and learn the names of its parts. See figure 2.1.
2. Disassembly and assembly of the Bunsen burner.
a. Unscrew the needle valve from the base by turning it counter-clockwise. Likewise, unscrew the barrel from the base. The needle valve, barrel and burner base are the basic parts of the Bunsen burner.
b. Observe the small hole in the center of the base. This hole allows a flammable gas to flow into the barrel by way of the gas spigot and hose.
c. Observe the air holes at the bottom of the hollow barrel. They allow the delivery of air (oxygen) into the barrel. The gas from the spigot and the air delivered into the barrel from the air holes are mixed inside the barrel prior to being burned.
d. Screw the needle valve back into the base until it stops turning. (Do not tighten!) Notice that the sharp end of the needle valve fits into the hole through the center of the burner base. Opening and closing the needle valve regulates the amount of gas that flows into the barrel.
e. Screw the barrel onto the base until it stops turning. (Do not tighten!) The air holes are now closed. (The burner base screw threads are blocking the air holes.)
3. Preparing the Bunsen burner for use.
a. Connect the burner hose to the gas outlet by pushing the open end of the hose over the ridges of the gas spigot. About one inch of the hose should be tightly fitted over the spigot.
b. Open (unscrew) the needle valve seven or eight turns. The barrel air holes should be kept closed.
c. Look at Fig. 2.2 and observe how to turn the spigot handle so the gas will flow. HOWEVER, Before you open the gas valve you must have a match lit and ready to ignite the gas.
4. Lighting the Bunsen burner.
a. When working with a partner, have one person strike a match and hold the burning tip near the top of the barrel as the other person opens the gas spigot. Igniting the gas will produce a sooty, luminous yellow flame. IF THE MATCH GOES OUT BEFORE THE FLAME IS LIT IMMEDIATELY TURN OFF THE GAS AT THE SPIGOT UNTIL ANOTHER MATCH IS READY! DO NOT LET GAS ESCAPE INTO THE ROOM.
b. To obtain the desired non-luminous blue flame, hold down the base of the burner and turn the bottom of the barrel counterclockwise (to the left). As the air holes at the base of the barrel are opened you will see the yellow flame turn blue as more oxygen is added to the gas. (It is perfectly safe to touch the bottom of the barrel or the Bunsen burner base while the flame is lit.) Stop turning the barrel once the air holes are fully opened (no screw threads showing) and the flame is blue. Watch for the appearance of the characteristic bright inner flame cone and the dimmer outer flame cone. See Fig. 2.1.
c. If you do not see the two flame cones, slowly turn the needle valve counterclockwise until the two cones form. It will be obvious when they do. Overall, the blue flame should be about 5 inches tall. If the flame is too short try adding more gas by turning the needle valve clockwise. Keep the air holes fully opened.
d. If the flame should unexpectedly go out immediately shut off the gas. Then follow the procedures above to safely relight the burner.
5. Determine the hottest part of the blue flame.
a. Ensure the two blue flame cones are formed. Test the inner cone by holding a wire loop on the top of the barrel for a minute. Raise the wire loop slowly, stopping at the top of the inner cone and finally at the top of the outer cone.
b. Where is the flame the hottest? (At the top of the inner flame cone.) How can you tell? The wire glows the hottest when held here.)
6. Heating with the Bunsen burner.
a. Place the properly lit Bunsen burner on an iron ring stand and position it so that the hottest part of the flame touches the bottom of the wire gauze pad. Adjust the height of the flame, if necessary, by turning the needle valve in the appropriate direction to add or reduce the amount of gas being burned.
b. Pour 150 mL of tap water into a 250 mL beaker. Measure and record the temperature of the water. Place the beaker on the wire gauze pad.
c. Heat the water over a blue flame for two minutes. Use beaker tongs to remove the beaker from the wire gauze and place it on the lab counter. Measure and record the new temperature.
d. Repeat the above step using a yellow flame. Turn the blue flame yellow by closing the air holes in the barrel. Again, use beaker tongs to move a hot beaker.
7. When finished, shut off the gas by turning the handle at a right angle to the gas spigot. See Fig. 2.3. Clean up your lab station and wash and dry the beaker. Finish answering the lab questions.
Bunsen Burner Lab
Names:______Period 1 2 3 4 5 6 7 8
Data Chart:
Initial Temperature / Final Temperature / Temperature ChangeBlue flame
Yellow flame
The final temperature for the blue flame will be higher than the final temperature for the yellow flame given the same amounts of water and the same heating time.
Questions and Conclusion:
1. What is the Bunsen burner used for? Heating substances.
2. What is the purpose of the needle valve? Regulate amount of gas entering the barrel.
3. What is the purpose of the barrel air holes? Provide oxygen to support burning the gas.
4. What is the purpose of the barrel? Mix gas and oxygen for burning.
5. How would you adjust the burner for a luminous (yellow) flame?
Decrease the amount of oxygen by turning the barrel to close the air holes.
6. How would you adjust the burner for a non-luminous (blue) flame?
Add oxygen to a luminous flame by turning the barrel to open the air holes.
7. Where is the hottest part of the blue flame? Describe and draw a quick sketch identifying the location.
At the top of the inner flame cone
8. Using your data, compare the effectiveness of the two flames. Which flame is better for heating substances? How can you tell?
Blue flame. The water heated to a higher temperature than the water over the yellow flame.