The Bunsen Burner

1 | Introduction

2 | Parts of a Bunsen Burner

3 | The Bunsen Burner Flame

4 | Procedure for Lighting a Bunsen Burner

5 | Safety Rules when Using a Bunsen Burner

6 | Summary

 

       

Click images to preview the worksheet and practical experiment for this lesson and the Year 7 Chemistry Workbook (PDF and print versions)

 

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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)

 

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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.

 

 

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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)

 

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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)

 

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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)

 

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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)

 

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Click images to preview the worksheet and practical experiment for this lesson and the Year 7 Chemistry Workbook (PDF and print versions)