Lesson video

Hello, welcome to today's lesson.

My name's Mrs. Clegg.

We're going to look today at the hazards, risks, and the precautions that we should take to stay safe and keep others safe in the laboratory.

This is part of the unit, Making Salts.

So let's start our lesson, and here's the outcome for today's lesson.

So by the end of it, you should feel confident in choosing the appropriate laboratory equipment, be able to identify and explain the meaning of hazard symbols, and appreciate why we need to have practical risk assessments.

And here are the key words for today's lesson.

Apparatus, a piece of equipment that is designed for a particular use.

Hazard, a danger associated with a substance or a piece of apparatus.

A risk assessment is the identification of both the hazards of doing a particular experiment and the ways that we can reduce the risk of harm from those hazards.

A risk is the chance of a hazard causing harm to us or others around us.

Precaution is an action that we take to prevent or reduce the risk of danger or harm.

Today's lesson is split into three parts.

We're going to look at selecting laboratory equipment first, then the hazard symbols, and finally, risk assessment.

So let's get started with the first part of our lesson.

Laboratory equipment.

We've usually got lots of choices of equipment that we might use when carrying out a chemical investigation, and you can see lots of pieces of equipment that you might recognise there in the trays.

Now we must choose the right apparatus for the investigation, and this ensures that we get valid and accurate results and also it ensures everybody's safety.

So let's think about heating, first of all, and the operators that we tend to use for heating might include the Bunsen burner, but you might also have come across hot plates or water baths.

So let's look at the pros and cons for each of these three pieces of equipment.

So a Bunsen burner, for example, is really useful for heating, for sterilising things, and also for combusting, for burning substances.

But a downside of it is the open flame which can be dangerous.

And sometimes it's very difficult to see, isn't it? A hot plate, it's a flat surface and we don't need any extra equipment.

But after prolonged use, you might get electrical faults.

A water bath is really good because it keeps a constant temperature pretty much.

It heats fairly evenly, and it's suitable for things which are flammable, but it's quite slow to reach the temperature that you are looking for.

So all three pieces here have got pros and cons, and it depends what type of investigation that you're actually doing as to whether which one is the best to use.

Various vessels can be used to carry out reactions.

A vessel just means a container.

So smaller vessels like boiling tubes and test tubes, they limit the amount of chemicals, quantity of chemicals that you can contain in them.

A boiling tube, typically, you could get about 50 centimetre cubed in there.

And a test tube, a maximum of 25 centimetre cubed.

It does mean, however, that reactions are safer because we've got smaller quantities.

And narrower vessels, actually, it's easier to see colour changes and observe.

If we need larger quantities for a reaction, then we can use beakers or conical flasks.

So both reaction vessels are available in a variety of sizes, and they have a lot of markings on them.

And these markings help us to see the total volume that each can hold.

You can see the beaker there that's marked.

The total volume it can hold is 600 millilitres.

And that conical flask, 100 millilitres.

Now they both have features that might influence you to choose a beaker or a conical flask for a particular investigation.

So let's have a look at those.

So the beaker has a spout so it's easier to pour, and it's also got straight sides of a beaker, which means you might need to use a steering rod to mix any chemicals together there.

The conical flask, you can see there's no spout so actually it's not as easy to pour contents from that.

So if you're pouring stuff from one to the other, you'd probably use the beaker.

It has nice sloped sides, which actually mean it's easy to swirl and mix the contents.

If we have a look at this, you can see them being swirled.

So you can see the mixing beaker, there's much more chance of that liquid being spilled in comparison to the conical flask.

So again, that might influence our decision on whether to use a beaker or a conical flask.

Let's look at how we hold equipment now.

So we've got tongs, and we've got test tube holders, and we've also got a retort stand with a clamp and boss.

Now tongs are pretty much all-purpose holders.

We can use them for virtually anything.

They have edged tips that provide a bit of grip.

There's a bit of friction there, but they're not really that suitable for holding glass equipment.

A test tube holder, the positives are that they can hold glass without breaking or damaging it, but they're only really useful for small glass tubes, test tubes or boiling tubes potentially, because the opening's not very wide.

And then the retort stand with clamp and boss, we've got no hands needing to be anywhere near the equipment to do the holding, but it just takes a little bit more time to set it up.

But again, you think about these things when you're deciding what to use.

Many of our investigations include liquids or solutions, and the apparatus we use to measure these chemicals can include dropping pipettes, measuring cylinders, or a burette.

Let's look at the pros and cons of those.

So a dropping pipette is accurate for volumes which are less than five centimetre cubed, but they're quite difficult to control in terms of the drops and so on.

The measuring cylinders, they're efficient for volumes over five centimetre cubed, but the larger the measuring cylinder gets, the less accurate it becomes, which is where we come to burettes.

They are the most accurate or precise piece of equipment we tend to have.

You control by the tap how much you can dispense or let outta the burette, but they are quite time-consuming to set up.

They're also quite expensive as well.

Other pieces of equipment that we use to measure, so we have balances, digital balances, And to be accurate, they must have the appropriate number of decimal places for the measurements that you need to take.

So some of our balances will only measure to one decimal place.

Some will measure to a much higher degree of accuracy and precision.

Stopwatches exactly the same.

To be accurate, they must have the appropriate time interval, minutes or seconds.

And then thermometers, again, pretty accurate pieces of equipment, but you must make sure you've got the appropriate temperature interval, one degree centigrade, five degrees centigrade, or even 0.

1 degree centigrade, and you need to make sure it goes up to the maximum temperature that you might need to use or the lowest temperature.

So there's no point in trying to measure the boiling point of water if your thermometer does not go up as far as 100 degrees C.

So let's have a quick check.

Which equipment would you select for an experiment in which a total volume of 100 centimetre cubed of solution is being swirled and reacted? Which piece would you use? Well done if you said A.

Remember the beaker, it would hold 100 centimetre cubed, which the boiling tube and test tube wouldn't.

But because of the straight sides, it's more likely to spill when you're swirling.

Another question.

Only a measuring cylinder can measure a volume of three centimetre cubed.

Is that true or is that false? Well done if you said false.

Why? Can you justify why? Well done if you thought about a pipette that can actually measure volumes that are small.

You could also use the syringe as well.

They can be quite accurate to volumes of three centimetre cubed or less.

So let's have a look at task A.

Sophia has lost the equipment list for her method, which is shown below.

What apparatus does she need to collect before she starts? And then explain your choices.

So have a look at the method and write an equipment list and say why you've chosen that piece of equipment.

Justify it.

Pause the video and come back when you've done that.

Welcome back.

Let's have a look.

So to measure 25 centimetre cubed of hydrochloric acid, she'll need a measuring cylinder, and the justification is to measure that 25 centimetre cubed of hydrochloric acid.

So she's going to need a reaction vessel as well.

And if you look at step three, it talks about adding magnesium to the vessel and mixing.

So the best vessel would be a conical flask.

And if we look at the amount of volume of liquid that she's going to need, she doesn't need one that's any bigger than 100 centimetre cubed.

She'll need a balance because she's got to measure out 0.

05 grammes of magnesium.

She's going to need a thermometer to measure temperature for step four, and she's also going to need a stopwatch because she's told to record the temperature after a minute.

So she needs to measure a minute.

So did you get all of those? Well done if you did.

So let's move on to the second part of our lesson, which is about hazard symbols.

Now I bet you've seen hazard symbols not just in the laboratory, but all over the place, and they provide vital information to help keep us safe.

So the road hazard symbols, which you will have seen around and about, what are they warning us of? They're warning us that the road's got a bend in it, two bends in it in actual fact, and that there's a gradient of 30%.

So chemical hazard symbols signpost to us, the users, about in what way or how a substance might be dangerous.

And what's important is that we're able to interpret those hazard symbols correctly to keep us safe, and safety for those using the chemical, and those in the same space where the chemical is being used as well.

Let's have a look at some of the common chemical hazard symbols.

Have you seen those around? Which ones have you seen in the lab? Have you seen any of these on chemicals that you've been using? You've probably also seen them if you have a look at household items. So this is a can of waterproofing spray for trainers, and you can see a variety of hazard symbols there.

So the first one is flammable.

That means you need to keep your spray away from any naked flames.

And this one's a health hazard, which means we need to be careful about where we're doing spraying, and it should probably be outside so that we're not breathing in too much of the spray.

And this one is an environmental hazard, so we should be careful about how this spray is disposed of when we're finished with it.

Let's have a quick check.

So which of these symbols would represent a serious health hazard? Well done if you said C.

So let's have a look at some more hazard symbols, especially the ones about our health.

So the big exclamation mark there means health hazard and it can cause skin irritation.

It can cause allergic reactions.

The next one is corrosive.

So you can see that the liquid there is causing a burn, for example.

So it can cause severe skin burns or damage your eyes.

The third one is serious health hazard and that may cause respiratory issues, breathing issue, and organ damage, and so on.

So pretty serious, that one.

and the last one, skull and crossbones, toxic, poisonous.

It could cause death if it's swallowed, or breathed in, or absorbed through our skin.

So there's a hierarchy there with these health symbols.

Let's have a look at some more.

These ones indicate a substance could cause a fire or an explosion.

So the first one means that the substances flammable so it could easily ignite if it's exposed to heat or sparks.

This one is the symbol for an oxidising agent.

So this is a chemical which actually can provide oxygen for a fire.

So it actually would intensify a fire.

This one is explosive, and so this chemical might explode as a result of heat, or a shock, or friction.

And the last one is compressed gas.

And the hazards for compressed gas are that there's a risk of explosion, there's a risk of asphyxiation, not being able to breathe, and there's also a hazard of frostbite.

Now we don't always see the immediate impact of some of the hazards that we might use.

So remember that trainer waterproofing spray had this environmental hazard symbol on it.

If that was to get into the water system, it could be damaging to plants and animals for example.

Radioactive symbol there.

The chemicals there can emit ionising radiation, which can cause serious health issues.

These might be cancer if a person is exposed to quite a lot of radiation.

And so people that work with ionising radiation often use dosimeters which help to track their exposure to radiation.

Let's have a quick check.

So these symbols were found on a bottle of oven cleaner.

What hazards do they represent? Well done if you said B, corrosive and flammable.

Another question.

Which symbol should label a substance that could cause chemical burns? Well done for B.

That's the symbol for corrosive substances.

Let's have a look at task B.

So what hazards are shown on this industrial cleaner? Select them from the options below.

Pause the video and come back when you're ready.

Welcome back.

Let's have a look at the answers.

So the first symbol there is for environmental hazard then we've got health hazard, and then we've got flammable.

Well done if you've got those right.

Let's have a look at question two.

So Izzy is preparing to conduct an experiment.

She's noticed the hazard symbols on the chemicals she's going to use have fallen off.

Suggest an appropriate hazard symbol for each of these chemicals.

Pause the video and come back when you're ready.

Okay, let's have a look at the answers.

So nail varnish remover contains propanone which ignites easily, so we need the symbol for flammable.

Sulfuric acid can cause burns if it touches the skin, so we need the corrosive symbol.

And copper chloride is toxic to aquatic life, that's water life, so we need the environmental hazard symbol.

Well done.

Let's move on to the last part of our lesson, risk assessments now.

So what are they? Risk assessments are careful examinations of situations to determine how best to maintain safety.

They include the identified hazards, so anything that could cause harm.

So you need to think, what is likely to cause harm? What is potentially dangerous? You need to include the associated risks of those hazards.

So what's the chance of that hazard causing a harm? What might happen? And then the precautions.

Sometimes we call the precautions control measures, and these are things that we need to do to reduce the risks.

How can the risks be avoided and what do we do if the risk occurs? So let's have a look at an example.

So you can see that snow is falling there and that might obscure our vision.

So what we need to do before we even set off on a journey is ensure that our windscreen wipers are in good working order.

And actually sometimes you have to sit and wait for a little while for your car to warm up enough for the windscreen wipers to be able to start working.

And then we've got snow on the ground, so the road might be slippery.

So use slower speed and increase the distance between the cars to reduce the risk of an accident.

Which one of the following is a precaution you might take when inline skating? So remember a precaution is something you do to help reduce the chance of harm.

So you would wear wrist guards.

Now let's have a look at a risk assessment in the laboratory now.

So most have similar hazards and risks.

So a general risk assessment might include some standard, fairly standard precautions, which I'm sure you are aware of.

So when we're using chemicals, that's the hazard.

The risk could be damage to our eyes or skin, so we would wear goggles.

And if anything was to splash on us, we would immediately wash those areas.

If we're using sensitive equipment and there's a risk of contamination, there should be no food or drink in the laboratory.

Chairs and bags or stools, there's a good risk of tripping over them.

And so as a precaution, they should always be stored securely out of the way.

And long hair, again, that could obscure your vision if you're looking downwards, for example, at something.

It could cause contamination if some of your hair follicles drop out, but also hair is very flammable, especially if you've used any products on them.

So we must tie hair back.

Now these all should seem fairly familiar to most of you.

Most of you will have these as your school science room rules.

Most of our investigations require the use of specific pieces of apparatus and chemicals.

And so risk assessments must address these specific hazards, risks, and precautions that the actual investigation takes.

So let's have a look at a risk assessment.

We've got some equipment set up there.

So what are the hazards possible? So glassware, we've got glassware there.

It could break.

So our precaution, how do we try and reduce the risk happening? We handle it with care.

We keep it in the centre of the bench so it doesn't roll off or get knocked off easily.

And what would you do if any were to break? You would use a dust pan and brush to sweep it up.

You shouldn't pick it up with your hands.

Bunsen burner, the risk is an open flame, so you would keep anything which is flammable, anything likely to burn well away from Bunsen burner.

Also be using a yellow flame when you're not using it.

And then you've got things like the gauze, and the tripod, and also the Bunsen burner barrel.

They get hot and they could burn you if you try and pick them up.

So the precaution is to leave it to cool and then handle it very carefully.

Now some risks are not related to the intended use of a chemical, but you should be aware of them.

So sodium chloride, salt, is not a hazard, but if sodium chloride comes into contact with concentrated sulfuric acid, it produces hydrogen chloride gas, which is corrosive.

And so a sensible precaution should be to isolate sodium chloride from concentrated sulfuric acid, and they won't be stored together, for example.

So let's have a look at a question.

A risk assessment examines only risks associated with an investigation.

Is that true or is that false? Well done if you said false.

And can you say why? What is a risk assessment? Remember, a risk assessment would include the hazard, the risk, and the precautions to keep everyone safe.

Understanding a risk assessment is a shared responsibility that helps to keep everybody safe.

So when you're working in the laboratory, you need to know what the risk assessment is.

It's not just for your teacher, and it's not just for somebody else.

It's for everybody.

Even if you are unaware of a specific risk assessment, you should wear eye protection and ensure open flames are controlled, and that you are aware of the equipment and chemicals around you, even if you are not using them.

Sometimes there's equipment and chemicals around for a class after you or from leftover from the class before you.

Don't interfere with it.

And you should always stand when you're carrying out an investigation because it's easier to step back if something happens than it is If you are sitting down.

You are less likely to get something spilled on you as well.

Let's have a look at task C.

I want you to match each hazard to the appropriate risk, and then I want you to measure each risk to the appropriate precaution.

Pause the video and come back when you've completed this task.

Welcome back.

Let's see how you did.

So sulfuric acid is corrosive and your precaution would be to wear chemical resistant gloves.

Conical flask is fragile, so handle it with care and keep it towards the centre of your worktop, your bench.

And bromine me water vaporises easily.

It's harmful if inhaled.

So you would use that in a fume cupboard or in a very well-ventilated space.

Well done.

Let's have a look at question two.

So I want you to write a risk assessment for the investigation Sophia was doing in task A.

So here was her method and there's the apparatus that we decided upon, and you can also see the reaction equation at the bottom there.

So pause the video and come back when you finished.

So how did you do writing your own risk assessment then? Shall we have a look? So here we've got our table, hazard, risk, and precaution.

So she's using glassware.

The risk is it could break, so handle it with care, keep in the centre of the bench.

You might also have said, if it does break, to use a dust pan and brush to pick it up.

You should also ask the teacher where to dispose of it.

Hydrochloric acid, so that's a health hazard and there's a risk of spills, so you should always be wearing goggles and you should clean up spills immediately.

And if needed, eyes or mouths need to be irrigated with water, and the teacher needs to be alerted.

Hydrogen gas is produced if you looked at the equation, and remember that that is flammable, and you must keep the reaction away from naked flames.

Well done.

You might also have talked about more general risks, such as hair tied back, stools, bags, et cetera.

So we've come to the end of the lesson now.

Let's have a look at our summary.

What have we learned today? So hazard symbols provide us with vital safety information about chemical substances.

Correct identification of the symbols is crucial for laboratory safety.

You need to know what they're telling you.

And correctly choosing and using the appropriate apparatus is essential for conducting experiments accurately and safely.

Safety protocols like wearing eye protection, tying long hair back, standing up, putting stools away and bags away, and ensuring good ventilation are essential when we're working with hazards.

And a risk assessment is something which identifies the specific hazards, the associated risks, and outlines the precautions to minimise those risks from happening.

So well done.

I hope you feel a little bit more confident about interpreting hazard symbols and why we have some of the rules in the lab that we do, and also the appropriate use of equipment.

Great job.

I'll see you next time.