Lab: How to Use a Bunsen Burner

Purpose: To learn how to use and adjust the Bunsen Burner, and to determine the hottest part of the flame.

Materials: Bunsen Burner Index Card Match “pin”

Procedure: Part One: Adjusting the Bunsen Burner

1. Examine your Bunsen Burner. The gas outlet at your lab station is connected to a rubber tube. The rubber tube is then connected to the gas inlet of your Bunsen Burner. 2. Located the barrel of your Bunsen Burner. The barrel is the long vertical tube. Locate the air vents of your Bunsen Burner (if so equipped). The air vents are on the outside of the barrel. The air vents allow you to control the amount of air that is mixed with the gas of the Bunsen Burner (in the barrel). If you have too much air or too little air in the barrel, then the flame will not burn properly. To begin with, the air vents should be located at about the “half-way point”.

3. When you turn on the gas you will hear a hissing sound. Either use the flint lighter or the electrical lighter supplied by Mr. Zim. Hint: If you try to light the Bunsen Burn from directly on top of the barrel, the force of the gas may blow out your match. Try lighting the burner from the “sides”. 4. When the burner is lit, adjust the air-gas mixture so that your flame is blue and silent and does not flicker. The perfect flame is about 10 cm high, pale blue, and almost colorless. If the flame is very large and/or orange-yellow, then there is not enough air mixing with the gas. You have to open the air vents and possibly reduce the flow of gas. Some Bunsen Burners have a needle valve on the bottom to control the amount of gas flow. For other Bunsen Burners, the gas flow is control by turning the outlet on your desk. If the flame separates from the burner, then there is too much air in the barrel; therefore partially close the air vent. 5. The flame is extinguished by closing the gas outlet on your lab table. Allow each of your lab partners to practice the lighting and extinguishing procedure.

Procedure: Part Two: Finding the hottest part of the flame.

1. Turn on your Bunsen Burner, adjusting it to produce a pale blue flame. You should see a flame that resembles two cones, an inner cone which may darker blue, and an outer cone which is lighter in color. SKETCH your observation in the data section below. 2. Is the flame equally hot throughout the flame? Let’s find out. With the help of your teacher insert an index card in the flame as diagrammed below. REMOVE the card immediately when it starts to scorch. Closely examine the scorched pattern on the card. SKETCH the scorched pattern in the data section below.

3. Now we will perform another test. Make sure your Bunsen Burner is off. Stick a pin through a match 0.5 cm below the match head. The object is to suspend the match inside the barrel of the Bunsen Burner using the pin to keep the match from falling in the barrel. Turn on the gas, light the burner the usual way and record your observations in your data section below. Turn off your Bunsen Burner.

Data and Observations: (Record on a Separate Piece of Paper)

1. Carefully SKETCH the blue flame and label the color regions. 2. Carefully SKETCH the scorched pattern of the index card. 3. Compare the two Sketches. Is there any connection between the sketches? 4. Judging from the two sketches, where do you deduce is the hottest part of the flame. Describe 5. What happened to the match 6. What could you conclude about the temperature of the flame where the match was located? 7. If you wish to heat an object strongly, where in the flame should you place it? 8. What are the four parts of the Bunsen Burner? 9. If the flame is orange yellow, what does that mean?