Safety in the science classroom
Safe heating of test tubes over a Bunsen burner involves pointing the open end of the test tube being heated away from others.  
The Bunsen burner flame can heat objects to beyond 600 oC. The blue flame, being the hottest, is not easy to see and can be very dangerous to anyone near by.

So when a Bunsen burner is unattended it must be placed on the safety flame. We do not use the safety flame to heat objects.
View the unit on the Bunsen burner.

 

Never run or walkabout carrying glassware with tongs.  
Lab coats are there for a reason and so are latex gloves and goggles. All three safety items provide a barrier between you and the hazard that you may be exposed to. Sometimes you will use dangerous chemicals in high concentrations. Two of these chemicals commonly used are sulphuric acid and sodium hydroxide. Both of these chemicals will burn the skin on contact, as shown on the right, and must be washed away as quickly as possible with water. Click to see the dehydrating power of concentrated sulphuric acid as it turns sugar into carbon. You can imagine what it does to skin.

 

However sodium hydroxide is particularly nasty as it tends to coagulate proteins, much like egg albumin turns into a solid white mass when heated. If it gets into the eye it turns the cornea permanently opaque, as shown on the right.

One way to protect against chemical spills is to wear goggles. Goggles protect the eyes and must be worn at all time, however, if a chemical does accidentally get into the eye it must be rinsed out immediately with water.
Ask your teacher for the location of the eyewash.

A lab coat and gloves protest the skin surface.

 

Always listen to the teacher's instructions and never predict the outcome of mixing chemicals. Even water can cause a serious fire. The image on the right shows a mixture of chemicals, mainly metal powders, in a dish. Upon addition of one drop of water the mixture spontaneously erupts into flames. It is just simple chemistry that must be treated with great respect and care.

 

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Even common table sugar can erupt into flames when mixed with the right chemical. Click to see this reaction.

 

Because chemicals can behave in unpredictable ways, they must be properly labelled when stored in the laboratory. Not all fires can be extinguished by pouring water onto the base of the fire. In fact sometimes we can increase the intensity of the fire by using water. Fire fighters must be aware of the potential danger in order to use the appropriate extinguishing method and this is where proper labelling on the outside of buildings is crucial.

 

 

Chemicals should always be treated with respect. Even if they appear not to be dangerous, such as rust and aluminium powder.

 

Take the reaction between rust and aluminium powder, for example. It is known as a thermite reaction, however, it underlines the importance of never mixing powders together. This reaction should only be done as a demonstration and always outdoors. Click to see the video. The chemical laboratory is full of hazards.

Another example is sodium metal. It reacts violently with water to produce hydrogen gas. An unsuspecting student might well get into serious problems if they were to use this dangerous metal inappropriately. Click to see the reaction which demonstrates how a small piece of sodium behave in water.

The reaction on the right, however demonstrates the unpredictable nature of this highly reactive metal. The explosion is very loud and such demonstrations, when using sodium, should always be done outdoors where students can be well back from the reaction vessel.

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Why do we put an unattended Bunsen burner on safety flame?
What three safety items provide a protective barrier?
Following instructions is very important in the laboratory. Give one reason.
The "Oxidiser" label is used for a particular chemical called potassium chlorate. What does the label suggest this chemical can do?
Name two hazards that a corrosive substance, such as sodium hydroxide, can pose to a student and mention two ways that can be used to protect against such hazards.
A chemical is labelled as "Corrosive". What does this mean and what type of chemical is it likely to be?

Look around the laboratory. Many different types of fire extinguishers exist. Why is it important to use the right one as opposed to using water? Explain. Identify two different types and explain under what conditions they are used.

Using sodium metal as an example, suggest a reason why it is compulsory to label all chemicals in the laboratory.
Under what category will sodium be labelled?
Why do buildings that contain chemicals have placards on the outside of the building identifying the type of chemicals present inside?
View the video on the right. It relates to the safety rule "Never eat or take food in the laboratory" Write a safety rule that best relates to the video. Explain why this rule is necessary.

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When using a Bunsen Burner to heat solutions in a test tube certain rules must be obeyed.

View the video on the right.

What dangers can you identify?

Write a rule for heating solutions in a test tube.

The student in the video is wearing protective gear. What is the safety gear worn and how will this help or not help?

 

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Look at the two students working in the lab pictured on the right.

The students are working with hazardous chemicals.

What safety rule is not being applied here?
What additional safety gear can the students benefit from?

 

A student was asked to set up a Bunsen Burner to heat a solution in a test tube. Looking at the picture on the right, comment on his technique.

 

Consider the picture on the right. Why is this referred to as the safety flame?

 

Consider the hazard signs shown on the right.


What type of chemicals are present in this laboratory?


In case of fire, what chemicals are present that will accelerate the fire?

 

 

Why must broken glass be placed in separate bins?

 

What is generally placed in this container? Explain why containers such as these are necessary.

 

 

What rule is this student breaking?