Staying safe

The answers to these questions lie in the findings of the report to the Royal Society, Risk analysis, perception and management (1992). The report finds that: 

People are more likely to take risks when:

• they are in control;
• the activity is voluntary;
• the risk is easily reduced; and
• there is a low risk to future generations.

People tend to dread things and therefore are not so willing to take risks when:

• things are out of their control;
• many people can be affected; and
• there is a higher risk to future generations.

So what are the implications for teaching health, safety and risk in the school laboratory?

On many occasions when meeting with teachers and technicians I hear phrases such as ‘You can’t do that experiment. It’s too dangerous’; ‘That chemical is banned, so we don’t do that practical activity any more’; ‘I’m nervous that it might go wrong so I don’t do cracking or the alkali metals. I will put on a video instead.’

Teaching students about health, safety and risk is an important part of the chemistry curriculum. A good starting place is to ask students to think about and discuss the hazards and risks t in everyday life. Then move on to more specific safety issues met in science. Activities such as Our perception of risk and the Risk and dread exercise in the Royal Society of Chemistry’s book Health, safety and risk promote such discussion.

Learning to carry out a risk-benefit analysis will help students to make balanced decisions about wider questions in society such as the use of food additives, parabens in cosmetics or nanoparticles.

Progression in teaching about health, safety and risk

Safe heating of chemicals

Heating is a key part of practical chemistry as many chemical reactions depend on heating to overcome the activation energy required to get the reaction started. There are several ways of heating chemicals including the use of Bunsen burners, water baths and electric heaters. Table 1 lists some questions to ask and things to think about when planning an experiment that involves heating.

Table 1 Questions to ask when planning an experiment that requires heating

Questions	Things to consider
What personal precautions should be taken?	Safety glasses or goggles? Tie long hair back. Clear working space. Stand or sit?
What are the risks associated with each method of heating: Bunsen burners, water baths, electric heaters?	Where you are doing the experiment: easy access to gas or electricity? If using a Bunsen flame, how do you control the size of the flame so that the clamp doesn’t catch fire?
What temperature is needed for the reaction to work?	Use a water bath if the temperature is below 100oC. Is it within the temperature range of an electrical heater?
Are any of the reactants or products flammable?	Avoid using a Bunsen burner near flammable substances, eg ethanol as this reduces the risk of them catching fire.
If the reaction gets too hot will any harmful by-products be made?	How to control the temperature so it doesn’t get too hot?
How do you avoid the reaction boiling over or shooting out of the reaction vessel?	Reduce temperature of heater or the size of the Bunsen flame. Use anti-bumping granules Think about the size of the heating vessel.
Can the experiment be done on a microscale?	Smaller quantities of chemicals are needed. Spirit burners can be used for heating.

The preparation of copper sulfate crystals

On first appearance preparing copper sulfate crystals in the lab is a straightforward practical activity that most secondary students will do at some point in their school careers. However, a high number of accidents and incidents are reported with this experiment – and they are usually down to heating

The practical problems encountered with this experiment are clearly shown in the video Demonstrating chemistry: Top of the flops (20.39 minutes) and those associated with heating summarised opposite. You can get further guidance on this method from CLEAPSS. This involves using a water bath in the first stage, replacing the evaporation basin with a conical flask and adding a couple of anti-bumping crystals. This provides practical solutions to the practical problems summarised opposite. Alternatively the microscale preparation of hydrated copper sulfate crystals uses small quantities of chemicals, replaces the Bunsen burner with a sand tray on an electrical heater and produces good quality crystals without the risks previously discussed.

Safe handling of glassware

Many chemical reactions are carried out in glassware. Glass needs to be handled carefully. It is brittle and breaks easily if it is dropped, rolls off the bench or is clamped too tightly. It fractures and shatters if subjected to heat shock, ie large sudden changes in temperature such as those that occur during a freeze–thaw reaction or suck-back of cold water into a hot reaction vessel. This principle can be easily demonstrated by heating the end of a thin glass rod in a Bunsen flame until it starts to glow then plunging it into a large trough of cold water.

Finally, glass will ‘flow’ if it is heated strongly. Glassblowers make use of this property as they craft a piece of glass into laboratory apparatus or beautiful ornaments. However, it can also cause difficulties if chemicals are strongly heated in cheap glass boiling tubes. A better alternative are the more expensive, tougher borosilicate glass (Pyrex) boiling tubes.

Students needs to be aware of these properties and of the consequences. When introducing a class practical or demonstrating an experiment it is good practice to discuss what could go wrong and the possible consequences. Students will learn about the hazards and know how to reduce the risk, so they can carry out experiments safely.

Learning about the safe handling of glassware is an important part of developing students’ practical skills and as teachers we should not assume that our students are aware of the hazards. Students are more likely to take note and feel more confident to carry out the practical activity when they understand both the reasons behind and the consequences of practical instructions. They will feel more in control of the situation and know how to reduce the risk of things going wrong.