Learning Objective
In this lesson we will learn about the different parts of a Bunsen burner, and how to use a Bunsen burner correctly and safely in a science laboratory.
Learning Outcomes
By the end of this lesson you will be able to:
- Identify the different parts of a Bunsen burner.
- Describe the different Bunsen burner flames and explain when each should be used.
- Describe the steps involved in the safe operation of a Bunsen burner.
Click images to preview the worksheet and practical experiment for this lesson and the Year 7 Chemistry Workbook (PDF and print versions)
Introduction
- A Bunsen burner is a portable gas burner used for heating, burning and sterilising materials in a laboratory.
- They are probably one of the first things you think of when you think of a schools science laboratory.
- Although you won’t use one every day, you will often use them when you need to heat something during a practical experiment.
- Before you can use a Bunsen burner, you need to know a little about them so that you can use them correctly and safely in the laboratory.
- We’ll start off by naming the main parts.
Although he didn’t invent the Bunsen burner, Robert Bunsen made important modifications to pre-existing designs, which lead to it being named after him.
(Image: Unknown, Wikimedia Commons)
The Barrel
- The barrel is the main upright part of the Bunsen burner and the part where the flames comes out.
- Never touch the barrel as it can get very hot while in use and can stay hot long after it has stopped being used.
The Base
- The base of the Bunsen burner is a flat disc that provides the support for it to stand up.
- It is also the safest part of the Bunsen burner to touch if you need to move or carry it, as it is designed not to get hot.
The Air Hole
- The air hole is an coverable opening above the gas inlet of the barrel allows air to enter the Bunsen burner, where it mixes with the gas.
- The air hole can be partially or completely covered by turning the collar.
The Collar
- The collar is an adjustable metal tube that for covering or exposing the air hole.
- This controls how much oxygen can enter the Bunsen burner, and therefore how much oxygen can mix with the gas.
- The more oxygen that is allowed to enter the Bunsen burner, the hotter the flame will be.
- Always light the Bunsen burner with the air holes completely covered by the collar.
The Gas Inlet and Rubber Hose
- The gas inlet is a tubular projection below the air hole where the gas enters the Bunsen burner and mixes with the oxygen.
- The rubber hose is a short section of tubing attached to the gas inlet that connects the Bunsen burner to the gas tap on your lab bench.
The Bunsen Burner Flame
- There are two main types of flame produced by a Bunsen burner – the yellow flame and the blue flame.
The Yellow Flame
- The first type of flame produced by a Bunsen burner is the yellow flame, also known as the safety flame.
- This flame is bright yellow and highly visible.
- A Bunsen burner flame will burn yellow when the air hole is completely covered by the collar.
- Since you always light a Bunsen burner with the air holes covered, the flame will initially be yellow.
- A yellow flame is the coolest Bunsen flame.
- Because the air hole is covered, less oxygen can burn with the gas, meaning the flame will not burn as efficiently.
- Once the Bunsen burner has been lit, it should remain with the yellow flame until you are ready to heat something.
- Leaving the flame is ‘safety mode’ means that:
- ▸ You are much less likely to accidentally put your hand or other object in the flame because it is bright yellow and therefore very easy to see.
- ▸ Any accidental burn would be less severe as the flame is the least hot.
- Never use the yellow flame to heat something.
- Heating with a yellow flame will cause glassware and other equipment to get covered in black soot, which is very difficult to remove.
- Also, since the flame is not as hot, it will take much longer to heat something.
The yellow Bunsen burner flame
(Image: Milesl, Pixabay)
The Blue Flame
- The second type of flame produced by a Bunsen burner is the blue flame, also known as the heating flame.
- This flame is light blue and not easy to see, especially in a brightly lit laboratory.
- A Bunsen burner flame will burn blue when the air hole is completely uncovered by the collar.
- A blue flame is the hottest Bunsen flame.
- Because the air hole is uncovered, more oxygen can burn with the gas, meaning the flame will burn more efficiently.
- There are two parts to a blue flame – the smaller, brighter section at the bottom, and the larger, less bright section above.
- The hottest part of the blue flame is the tip of the smaller, brighter section.
- Whenever you heat something, such as a piece of magnesium ribbon or a test tube, always hold it at this hottest point.
- Only use the blue flame when you are heating something; at all other times return the Bunsen burner to a yellow flame.
- Since the blue flame is more difficult to see and much hotter than the yellow flame, you need to be very safety-conscious when using it.
The blue Bunsen burner flame
(Image: Swn, Wikimedia Commons)
Procedure for Lighting a Bunsen Burner
- The procedure below should be followed each and every time you use a Bunsen burner.
- Put on your safety goggles and lab apron. If you have long hair, make sure it is tied back.
- Collect your Bunsen burner.
- Connect the rubber hose to a gas tap.
- Place a heat mat under the Bunsen burner.
- Turn the collar so that the air hole is covered.
- Light a match and hold it about 3 cm above the top of the barrel.
- Turn the gas tap to the ‘on’ position.
- Once the Bunsen burner is lit, extinguish the match.
- Leave the Bunsen burner flame in ‘safety mode’ until you need to heat something.
There is a procedure that should be followed when lighting a Bunsen burner.
(Image: Swn, Wikimedia Commons)
Safety Rules when Using a Bunsen Burner
- Although it is fun to do scientific experiments that involve using a Bunsen burner, it can potentially be very dangerous if not used correctly and safely.
- Therefore, in addition to the general laboratory safety rules, there are several very important safety rules specific to using a Bunsen burner that you need to be familiar with.
- Always wear safety goggles and a lab apron when using a Bunsen burner.
- If you have long hair, always tie it back when using a Bunsen burner.
- Always light the Bunsen burner with the air hole covered by the collar.
- Always light a match and hold it above the Bunsen burner barrel before turning on the gas tap.
- Never turn on a gas tap on without a Bunsen burner attached and a match lit above the barrel.
- Extinguish the match immediately after lighting the Bunsen burner.
- Always leave the Bunsen burner on the yellow safety flame when you are not heating anything.
- Always leave the Bunsen burner on the blue heating flame when you are heating something.
- Only put something in a flame if you are instructed to by your teacher.
- Never put your hand in a Bunsen burner flame.
- Never reach across a Bunsen burner flame.
- Always extinguish a Bunsen burner flame by turning off the gas tap.
- Never attempt to blow out a Bunsen burner flame.
- If the flame accidentally goes out, turn the gas tap off immediately.
- If there is a fire, immediately turn off the gas tap and alert your teacher.
Safety gear should always be worn when using a Bunsen burner.
(Image: Airman 1st Class Micaiah Anthony, US Air Force)
Summary
- The main parts of a Bunsen burner are:
- The barrel.
- The base.
- The air hole.
- The collar.
- The gas inlet and rubber hose.
- There are two types of Bunsen burner flame:
- The yellow safety flame.
- ▸ Less hot flame
- ▸ Highly visible
- ▸ Use whenever you are not heating something
- The blue heating flame.
- ▸ Hotter flame
- ▸ Harder to see
- ▸ Use only when you are heating something
- There is a correct procedure that must be followed every time you light a Bunsen burner:
- Always wear the correct safety gear.
- Always light a Bunsen burner with the collar closed.
- Only turn the gas tap on when a lit match is above the barrel.
- Always extinguish a Bunsen burner flame by turning off the gas tap.
- Always follow the safety rules when using a Bunsen burner.
- Only use a Bunsen burner for the purposes instructed to you by your teacher.
(Image: Jan Fijałkowski, Wikimedia Commons)
(Header Image: biker3, Adobe Stock)
Click images to preview the worksheet and practical experiment for this lesson and the Year 7 Chemistry Workbook (PDF and print versions)