Hello, my name's Mrs. Navin and today we're going to be using what we've learned previously about answering those big questions of what substances are made of and how substances behave in order to separate a specific type of mixture.

Now you may have some experience of what we talk about in today's lesson from your previous learning, but what we also learned from today will help us as we consider sometimes the best way to separate out the product of a reaction mixture as we go forward.

So by the end of today's lesson, you should not only be able to identify some of the essentially equipment required for simple distillation, but also explain how that process works.

Now throughout the lesson I'll be referring to some keywords and these include boiling, distillation, condensation, condenser, and distillate.

Now the definitions for these keywords are given on the next slide and you may wish to pause the video here so you can jot them down somewhere so you can refer to them later in the lesson or later on in your learning.

So today's lesson is broken into two parts.

We'll first look at how we can explain distillation and then we'll take a closer look at the equipment that's required for simple distillation.

So let's get started by looking at how we can explain how distillation takes place.

One thing that's worth remembering when we talk about distillation is the fact that substances in a mixture have very unique boiling points.

And so because of that they're going to evaporate at very specific temperatures.

So we have an example here that is a mixture of two liquids of water and ethanol, but we can see that ethanol will actually start to boil at a lower temperature compared to water.

But if we look at another mixture that contains water, this time we have water mixed with different inks.

We can see that water has the lower boiling point at 100 degrees Celsius, whereas the inks could boil anywhere between 150 to 290 degrees Celsius.

And then if we look at a third a mixture here, we have sugar which is a solid that has dissolved within our water and sugar would still potentially boil depending on the conditions at 398 degrees Celsius and water would still boil at a 100 degrees Celsius.

So we have water that's part of three different mixtures and the boiling point doesn't change, but it's boiling point in relation to the other parts of the mixture is different and that's significant.

So if we take one of these mixtures and start to heat them, the substance with the lower boiling point is going to boil first.

And what that means is that it changes from the liquid state into the gas state before the other substances in the mixture.

So that means that by heating a mixture, we could actually separate a liquid from it.

But here's the thing, once boiled that substance when it's removed, it's being removed 'cause it's less dense, and what it does then is it rises into the air and mixes with the air and surroundings, which means effectively we've lost that particular component from our mixture.

Let's stop here for a quick check.

I'd like you to use the information that's provided in the table to decide which of these substances would boil first.

Well done if you said ethanol.

Ethanol would boil before the camphor or the octane because it has the lowest boiling point of 78 degrees Celsius.

So well done if you managed to get that first question correct.

Great start guys.

So this diagram here shows the setup for an example still and is still is really useful for very simple distillation that you might be able to perform in the lab.

Now distillation is actually a separation technique that uses and exploits changes of states in order to separate and isolate and keep a liquid component from a mixture.

Now, simple distillation that we're gonna talk about today is usually used to separate mixtures of only two components.

Now I said that distillation is a process that uses changes of state and the changes of state that are exploited in this process is boiling and condensation.

So how does it work? Well, the first thing that happens is that the mixture is going to be heated and it's heated until one of those components starts to boil.

So it's changing from the liquid state into the gas state.

And we can see at the top of our conical flask here that it has been bunged, but there is space for that gas that is now formed from one of the components in our mixture is able to then move into that delivery tube.

So it's collected through that delivery tube and transported to another container.

Finally, what happens then is as that gas substance is moving away from the heat source, it starts to cool and we know that when a gas starts to cool it can condense and when that happens it's changing from the gas state back into the liquid state.

So let's see how well you were paying attention.

Which processes take place during distillation? Well done if you said d.

Boiling and condensation is what takes place.

Boiling and freezing would not work because freezing is when something changes from the liquid state into solid state.

We don't have solid state changes.

The same is true for b because melting as we are going from a solid into a liquid state as well as for c.

So a, b and c are incorrect answers because they all include a change of state that involves a solid and we are looking at in distillation only the changes of state between liquids and gases.

So well done if you manage to get this check correct.

Great job guys.

Believe it or not, it is time for our first task of the lesson.

What I would like you to do please is to explain the process of distillation.

What is happening to our substance as it undergoes distillation.

And I'd like you to try to include some key features of what's happening to this substance.

What are some key words that you think should be included in your explanation? Now sometimes this can be quite a daunting task and we dunno where to start.

So if that is you and you are struggling, I'm going to recommend that you try to aim to write a sentence explains what's happening at each letter shown in the setup as a guide.

And you may wish to pause the video here so you can think through, get your ideas down on paper and then come back to check your answers when you are ready.

Okay, let's see how you got on.

So one of the things that I would say is a key feature of distillation is actually defining what it is.

It is a separation technique.

It is a way to separate out a mixture.

And it does that by exploiting the different boiling points of the components in that mixture.

So if you said something about separation technique and boiling points, you are off to a flying start with your answer here.

So very well done.

Now what I'm going to do is follow then the suggestion I gave in the task instructions of writing a sentence for each of the different lettered parts of my diagram here just as a guide.

So the first thing we have here that's happening at position A is a mixture is heated and it's heated until one substance starts to boil.

And I've defined what boiling is, which is changing to the gas state.

You could have added also from the liquid state.

But we eventually say the first thing that happens is the substance is heated until one component boils.

What happens next then is that gas substance rises into a delivery tube and it's transferred to a another container, okay? So it moves position away from that starting mixture.

And finally what happens then is as the gas substance travels away from that heat source, it's gonna start to cool down.

And when it does that it condenses from the gas state back into the liquid state and has been collected elsewhere.

So lots of things that you could have said here.

What I would focus on if you are trying to give yourself marks for your answer is the fact that we said it exploits different boiling points.

That it starts by the mixture being heated until one component boils.

It's transferred, then that gas substance is transferred to another container.

And finally for a fourth mark, I would say something about that gas substance condensing back into the liquid state.

Now what you might want to do at this point then if you have a highlighter or coloured pencil is to go back and just double check or highlight underlying circle those key ideas within your own answer or add them in so that when you come back to look at your work, you can see how you can improve or did well in your first attempt.

So great, great start guys, good job.

So for the second part of this task, what I'd like you to do is to again look at our simple still that is shown here and I'd like you to tell me what is the name and the state of matter of the substance that is found at both position X and position Y.

You may wish to pause the video here and come back when you're ready to check your answer.

Okay, let's see how you got on then.

So the first thing I'm gonna see in my diagram here is that my mixture is a salt solution.

And you may remember from your previous learning that a solution means that water is present, and also from your previous learning you may remember that water being a liquid and salt is normally a solid that is soluble.

So the X position is the start of that delivery tube.

So what I need to think about then is which has boiled first.

The salt or the water in my solution? So at position X, hopefully you said it's water in the gas state or steam I would accept 'cause that is water, what we call water in the gas state.

So well done if you managed to get those.

If you only got one but forgot to do the state of matter, give yourself half a mark.

For b, then I ask you to name and state the substance found at Y and we can see that Y is in the other container and it looks like it's surrounded by ice cubes, which means it's quite cold space, which tells me that whatever was in that delivery tube will have cooled and potentially condensed, and so therefore I have water still, it hasn't changed into something different as it travelled through that delivery tube, but it is now in the liquid state.

So well done if you managed to get that correct.

Now that we're feeling a little more comfortable explaining how distillation takes place, let's take a closer look at the equipment that's required for simple distillation.

Now I said earlier in the lesson that simple distillation is used to separate a mixture of only two components.

Now the thing is if both of the components in that mixture are liquids, it might be more useful to use specialist equipment rather than a simple still in order to achieve better separation of the components in our mixture.

So let's take a closer look at this specialist equipment.

Now we saw in the last learning cycle that distillation is composed of three main actions really.

The first is that the mixture is heated until one component boils and then that gas substance that forms is transferred to another location and then the gas substance is cooled and it condenses back into the liquid form.

So what I'm going to do here is we're gonna talk about the equipment that's used for simple distillation and kind of build up that rather complicated setup we saw previously.

So the first thing have is where our mixture is held and heated and that's gonna be in a round-bottom flask.

And the reason we use this particular type of flask rather than something like a conical flask or even a boiling tube is because it's going to heat that mixture really nice and evenly.

The next thing you'll see in this setup is a thermometer.

And what that's doing is monitoring the temperature of the gas.

We're looking at its boiling point.

And the key thing about this is the position of that thermometer.

It's not down in the mixture, it's not down in the flask just above the mixture.

It is actually located just below that sidearm connector into the next part of our setup.

And that's because at that point we can see what the boiling point is, what is the temperature which our liquid substance firm mixture has managed to turn into a gas and stay as a gas all the way up before it is pushed into that next part of our setup.

Now arguably one of the most important pieces of apparatus that's gonna be used in distillation is the condenser.

And that's because this is where that all important change of state of condensing and condensation of that gas substance back into a liquid is going to take place.

And it takes place because a condenser is essentially a tube that is surrounded by a cold layer and that is usually cold water.

Now you will have seen examples of these in lots of different places, but maybe thought it looked like something else.

So for example, you could have a Liebig condenser here, which is what we normally have in the school labs, or you may have even seen a Graham condenser maybe in a display or if you've had a chance to go elsewhere and use one of these.

But they all, regardless of what they look like, have the same job.

It's a tube surrounded by a cold layer and that is allowing a gas substance to change back into the liquid state.

So we have now added a condenser to our setup and it looks a little bit like the Liebig condenser we saw previously.

But the thing to remember about a condenser is that, it's essentially a cold corridor, okay? And it's kept cool by a water jacket.

So we have an inner tube where the gas is travelling through and then surrounding that tube is this cold water.

So you are gonna have a tubing that's connected at one end of your condenser that's usually then attached to a cold water tap, and then that water will rush around the outside of that inner tube keeping it nice and cold until the water then is pushed out that top part of the condenser and that will also have some tubing attached to it and probably the other end will be in a drain, okay? So we'll have that water continually on and so that cold corridor is being continually renewed with that cold water.

And the thing to remember about this then is the cold water that's cooling down that inner tubing does not actually mix with the gas that's going through it.

All it's doing is keeping that outer surface of that inner tube nice and cold.

So what we have then as a result of this condenser being attached is our gas substance has now managed to condense back into a liquid.

You can see that in our condenser that is as it enters it on the left, it's in the gas state and as it leaves on the right it's in the liquid state, we can see that with the little droplets that are formed.

It then will travel through a delivery tube where it's going to be collected in a container of your choice.

Now this condensed substance then tends to be the pure liquid and it's then referred to as a distillate.

So it is the product of distillation Now that we've gone through all the specialist equipment that would be used for simple distillation, if you'd like to watch a demonstration of how it can be used to separate a simple mixture containing just ink and water, you can click on that Watch button below and watch that video.

So the first thing we're gonna do when we do our distillation is to put our sample into the round bottom flask.

And then when we set it up, this is what we'll look like.

So we have a tube running from a tap to the bottom of our condenser, and then another tube from the top of the condenser that is going to be leading into the drain.

So when the water is turned on, it's not gonna spill all over the place.

So we turn the water on and we can see it start to fill from the bottom.

Now you'll notice that there are a lot of water going in, but there's air bubbles as well.

Those need to be removed so that you've got that lovely cold corridor now filling up with our condenser and so the water is left to run whilst we turn the heating mantle on.

Now heating mantel is essentially and electric heater, so we can control the heat a little bit better than we might be with a bunsen burner and we can actually put the round bottom flask within it.

Then our thermometer is set up so that it is just at the tip where the side arm is and we can start to see that our mixture is starting to warm up.

We've got some condensation on the inside there and we can see that the temperature has increased by about 10 degrees, so it's now about 30 degrees.

Now we can see that it's starting to boil with the bubbles forming, So we know that the temperature's going up even further as it starts to heat a little bit more evenly in that mantle.

And we check our thermometer and we can see that it's now up around about 55 degrees and rising.

So now we're at about a 100 degrees centigrade and we can see that there is now a gas that has gone into and has condensed down into our test tube and is pure.

Let's stop here then for another quick check.

Which piece of equipment must be kept cool during distillation? Well done if you said c, the condenser must be kept cool because otherwise the gas would not be able to cool down in order to change from the gas state back into that liquid state.

Well done if you managed to get the correct piece of equipment there.

Let's try one that's a little bit trickier.

So the solution we have in our setup here has been heated to a 100 degrees Celsius and I would like you to suggest what colour the distillate might be shaded.

Now this is a little bit trickier.

You might want to pause the video here so that you can have a think, maybe discuss it with your neighbour and come back when you're ready to check your answer.

Okay, let's see how you got on.

Well done if you chose d.

The key here is that it's a copper sulphate solution.

So remember, solution suggests that water is present and it's also been heated to a 100 degrees Celsius.

And we know that water boils at 100 degrees Celsius, which suggests that it's the water that's being removed from this solution and water should have no colour, therefore the distil distillate will be left unshaded.

Well done if you manage to get that correct, that was a tricky one.

Okay, let's move on then to the last task of today's lesson.

What I'd like you to do in this first part is to match up each term to the correct definition or description.

And you may wish to pause the video here, maybe consult with those nearest you and come back when you're ready to check your answers.

Okay, let's see how you got on.

So the condenser should be matched up to that bottom description, which is a tube surrounded by a cooling layer.

So that was kind of the giveaway, the condenser cools.

Well done if you got that.

The delivery tube then is the thin tube that transfers a substance from one container to another.

So it's delivering or transferring something from one place to the other.

The distillate then is the liquid that condenses from the gas during distillation.

It's the final liquid product that we get as a result of distillation.

So well done there.

The round bottom flask is what transfers the heat rather evenly to its contents.

So that's one of the reasons why we use it in distillation.

And then the thermometer, hopefully you got that correct, it monitors the temperature.

More importantly is keeping track of boiling points within our distillation set up and the gases that are moving through it.

So well done if you manage to get all of those correct.

Okay, let's move on to the second part of this task.

Now, Aisha and Jun are discussing distillation setup options and I'd like you to decide who you agree with and why.

Now, before we go with what Aisha and Jun are actually discussing here, I'd like to remind you that whenever you see a question like this, who do you agree with and why? There's not really a right or wrong answer here.

It is simply what are your thoughts and why do you think that? So I'm looking for in your answer a because clause.

Why do you agree with this person? Okay, so Aisha thinks that a cold water condenser means most of the boiled substance condenses before it's collected.

Jun suggests that using an ice bath to condense the boiled component would be cheaper and more environmentally friendly.

So who do you agree with and why? Now this might require a little bit of discussion and thought, so I'm gonna suggest you pause the video here and come back when you're ready to check your decisions.

Okay, let's see how you guys got on.

So if we remember, Aisha was suggesting that using a specialist apparatus that cold water condenser meant that more of the boiled substance would condense before it's actually collected in that container.

And she's not wrong.

Really using a cold water condenser would allow for more efficient condensation.

And what that means is that more of the gas would actually condense back into a liquid before it gets to the end of that condenser.

Remember, as you're heating your mixture, more and more gas is being produced and that's pushing the gas in front of it through that condenser.

So if you're able to cool it faster, more of that gas is actually going to condense before it gets to the end, and that means less of it is lost to the surroundings.

As a result, you get more of your liquid or distillate at the end of that particular distillation process.

Now, Jun has suggested that using an ice bath to condense the boiled component is cheaper and more environmentally friendly.

Now again, he's not wrong either because if you use an ice bath, you don't need to have any specialist equipment.

So yeah, it's gonna be a lot cheaper, but there are some drawbacks to that because some of that gas could be lost to the surroundings, so you're gonna have less distillate.

Now if you are actually losing some of that gas, it might mean that you are using a little bit more fuel needed to actually heat more of the mixture to create more gas to have an equivalent amount of distillate using an ice bath to condense rather than your cold water condenser.

So there are pros and cons of using both setups, it's just which do you prefer and why.

So double check you've got a because clause in your answer 'cause that was the most important part of the task here.

So well done on a tricky discussion.

Okay, moving on to the last part of the last task of today's lesson.

Jacob here needs your help to design a still that he could use to obtain some clean water from muddy water while he's out on an expedition.

Now the items that he's gonna have in his pack, it might be useful to you, include having a camp stove, a kettle, he's gonna have a straw and some elastic bands.

There's a towel in his bag as well as some matches and a mug.

So the first thing I want you guys to do is to sketch a diagram of the setup you might use to obtain some clean water from muddy water, but I also want you to in your diagram label where the boiling mixture is, where your condenser is and where your distillate is going to be collected.

Once you've done that, I'd like you to explain how your still would maximise the amount of clean water that Jacob is able to obtain from that muddy water sample.

Now this is gonna take a little bit of time.

You might need to rub things out, so possibly use a pencil in case you wanna change ideas.

Pause the video and come back when you're ready to check your answers.

Okay, let's see how you got on.

So the first thing I asked you to do was to sketch a diagram of the setup you might use from Jacob's equipment and to add these specific layers.

So your diagram might look a little bit like this.

Now you can tell I'm no artist, okay? What I haven't done is labelled all the different pieces that I have used of his equipment, but I have included the labels that were suggested here, and that's the boiling mixture.

Should be above your heat source, probably in the kettle, the condenser of some sort.

So what I have here, which is unlabeled and maybe I should have labelled, is actually the straw that's been attached to the end of the kettle and has been surrounded by the towel.

And then finally the distillate is going to be collected in the mug at the other end of my condenser.

So as long as you've got something showing where the mixture's being boiled, that you have some form of condenser.

So something that's able to cool down the gas that's forming and something that could collect your distillate, you are on the right path, well done.

The second part then of this task was for you to explain how your still would maximise the amount of clean water that Jacob can get from his muddy water sample.

And I suggested the condenser here that I had a towel soaked around it, okay.

So wrapping a towel, particularly one that's soaked in cold water around the straw that I've drawn would kind of simulate what a cold water condenser is where we have that cold corridor.

And what that's gonna do is ensure that more water is able to condense as it goes through that straw and before it's being collected in the mug.

So less of it is lost to the atmosphere as it gets to the bottom of that straw.

If the towel was wrapped around the mug, the boiled water might be lost to the air in the atmosphere instead.

That's why it's really important it needs to be wrapped around that condenser.

So that was a super tricky question guys.

I hope you had a good time discussing it, thinking about how you might set up your equipment, getting some ideas about how you could make the most of the equipment that you're using to get the most amount of water from that muddy sample.

So well done on what was a tricky task.

I'm really proud of you for persevering with this great job.

Okay, so we've got just enough time then to go back through what we've learned in today's lesson.

So we've learned that distillation is a technique and it's a separation technique in particular that exploits differences in boiling points to separate out the components of a mixture specifically or more frequently at least, to separate a soluble substance from a solvent in a mixture.

Now two changes of state take place during distillation, that is boiling and condensing.

And if we use some very specialist pieces of equipment that are connected in a very particular order will help us to achieve the most successful separation of our mixture, particularly if we have a cold water condenser being used.

And finally, simple distillation is used primarily to separate mixtures of just two components.

If we want to separate a mixture that contains more components, we might need to adjust our distillation setup a little bit differently.

I had a great time learning with you today.

I hope you did too, and I'll see you again soon.

Bye for now.