Hello, my name's Mrs. Niven, and today we're going to be looking at distillation in order to separate a mixture of inks as part of our unit on separating substances.

Now, you may have some experience about what we talk about in today's lesson from your previous learning, but what we do today will help us to answer those big questions of what are substances made of, but also how can substances be changed and made.

By the end of today's lesson then, you should feel more comfortable being able to describe how to successfully separate the components of ink.

Now the key words that we'll be using throughout the lesson are given on the next slide, and you may wish to pause the video here so you can jot them down for reference either later on in the lesson or later on in your learning.

So today's lesson is broken into two parts.

Firstly, we'll remind ourselves how to prepare for distillation before looking more closely at how to separate a solvent from a mixture of ink.

So let's get started by looking at how we can prepare for the process of distillation.

Firstly, we want to remind ourselves that a simple solution is usually composed of a solute, which tends to be a soluble substance that's dissolved in a solvent, which tends to be a liquid.

So if you look more closely at the pictures here, my soluble substance then is known as the solute, the liquid is my solvent, and when they are mixed together, they will form then my solution.

Now, components of mixtures that are solutions will have unique boiling points.

Now that means then that each component will change state at a specific temperature.

So if we were to take a solution, then the substance that has the lower boiling point will change from the liquid state to the gas state first.

Let's stop here for a quick check.

If I had a mixture containing chloroform, ethanol, and bromine as shown in the table, which of them would change state first when heated? Well done if you chose C, bromine.

Because bromine has the lowest boiling point, it would change state first when heated.

Well done guys.

Great start.

Distillation then is a technique used to separate a mixture that's a solution by exploiting those unique boiling points of the components in that solution.

So what happens then is the process is using both boiling and condensing to not only separate, but also isolate each component in that solution.

Now there are three main steps that occur when carrying out distillation.

The first is heating that mixture, that solution, and that's going to be heated until one component starts to boil.

The next step then is that gaseous component now is going to be collected and moved to another container.

So in the setup we have here, it's collected in the delivery tube and transferred or moved into another container shown here as a test tube.

The third step then is that gaseous component is going to cool and condense back into a liquid state.

And again, in this particular setup, it's helped to be cooled using that ice water bath.

Now, even if you use different equipment for distillation to take place, the same steps are occurring, they just may take place in a different part of your setup or possibly in a different order.

So if we look at this setup, we're still heating that solution to start with until a component boils.

Then that gaseous component moves into a condenser and it's here where that gas is going to cool and condense, and then eventually, that liquid is collected in another container.

So even though it's slightly different setup, the same three steps are occurring.

We're heating a solution until one boils, cooling and condensing is taking place and the collection of that now changed back into the liquid state component is collected elsewhere.

It's been isolated.

Now, regardless of the setup that's used for distillation, the component that is collected at the end is known as a distillate, and we can see that here, it's been collected in a different container, and if this distillation has been completed successfully, that distillate should be a pure substance.

Let's stop here for another quick check.

"What process would produce pure water from a fruit juice mixture?" Well done if you said C.

Distillation can be used to separate the pure water from a juice mixture.

So well done if you managed to get that correct.

Great job.

So we've looked now at two different distillation setups, but why would you choose one over the other? Now this particular simple distillation setup is very commonly used.

It's using equipment that is easy to access, but it does have some limitations.

For instance, there's no thermometer, so it's very difficult to monitor the boiling points of any of the components as they start to boil.

Also, condensing is occurring at the very end of our setup, and as a result of that, there's gonna be potentially delayed or poor cooling of that gaseous component that's boiled and that could lead to inefficient condensation, potentially the loss of some of that gaseous component that's been boiled.

Now, there is a secondary effect of this because if you lose that gaseous product, it's actually going to be very hot, and it could be a safety hazard.

Using a different setup for distillation could address some of those limitations of our simpler version.

For instance, by using a bung at the top of the flask in the setup, we can actually hold a thermometer in place and allowing for that monitoring of the boiling points.

Additionally, if we use a condenser, that could lead to more efficient and safer condensation because condensation is gonna happen more quickly because it's happening earlier in the distillation process.

And because of that, more of that gaseous component could potentially be condensed, which means less of it is being lost to that environment, making it more efficient.

Now, you may have noticed that one of the big differences between our two distillation setups is this use of a condenser.

So let's take a closer look at it.

When we look at it, it looks like it's made out of two parts that are connected.

The first part is essentially a cold corridor.

That's an inner tubing within our condenser, and it's kept cold by the outer part of this condenser.

It kind of wraps around the entirety of our condenser, and I like to refer to it as a cold jacket.

And the reason it's kept cold is because water is pumped into the condenser from a cold water tab at the very bottom of that condenser.

The pressure of that water flow then pushes water around the outside of that corridor creating the jacket, and then the water finally is pumped out at the top of that condenser and it's left on, so it's constantly renewing the water, keeping it nice and cold around the outside.

The key idea then about how this condenser works is that the cold water that's being pumped around the outside of our condenser does not mix with the gaseous component that's travelling through that cold corridor on the inner tubing.

Okay, let's stop for another quick check.

"Which improvement or improvements might make this particular distillation setup shown more safe and or more efficient?" Now, you may wish to pause the video so you can discuss your ideas with the pupil nearest you, and then come back when you're ready to check your answers.

Well done if you said A, C, or D.

All of these ideas will help to make this distillation set up more safe and more efficient.

Fantastic work if you've got at least one of them.

Incredibly well done if you've got two or more of these suggestions.

But the main idea here to to think about is that being able to reflect a practical setup and consider ways in which to improve it is a key skill of any good scientist so very, very well done if you've got any of these correct, great job guys.

I'm really impressed.

Okay, time for the first task for today's lesson.

What I'd like you to do is to use the words provided to label this distillation setup shown.

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

Okay, let's see how you got on.

So if you were to label this correctly, you have your flask that is being heated, then we have a thermometer that is held in place by the bung just above the flask, then we have our condenser showing that cold water corridor, but we need to make sure that the water is travelling in to create that cold jacket at the bottom of the condenser, and then the water is flowing out at the top of the condenser closest to the thermometer, and then finally, we have our distillate that is being collected in the beaker on the far right.

So well done if you manage to label all of that correctly.

For the next part of this task, I'd like you to consider Alex's setup to distil a sample of inky water.

First, name the apparatus that has been labelled Y in the diagram, and then I'd like to see if you can identify the error Alex has made when setting up his equipment.

Also, once you've identified that error, can you explain why that would result in no water being collected using Alex's setup? So pause the video here and come back when you're ready to check your work.

Okay, let's see how you got on.

The first thing I asked you to do was to name the apparatus that was labelled Y in the diagram, and that is a delivery tube.

You then were asked to identify the error Alex made and explain why that would result in no water being collected.

What he didn't include was a bung or a stopper in that flask.

So that means that steam or gas escape from the flask and didn't actually enter that delivery tube in order for it to be collected in the other side of our apparatus in that test tube.

So by not forcing the gas that's being collected into the delivery tube by including a bung, that steam or that gas was lost to the environment.

Well done if you managed to identify the error and incredibly well done if you managed to explain the effect of that error.

Great job, guys.

Now that we're feeling more confident preparing for distillation, let's move on to look at how we can use it to separate a solvent from an ink mixture.

Now, believe it or not, an ink whilst being a solution, is actually quite a complex mixture.

It contains a variety of components including things like a solvent, pigments, and dyes that give us our colours and some other substances as well that help that ink to adhere to different surfaces and things like that.

Now, the primary purpose of a solvent in an ink is to help other components like pigments and things to dissolve into the mixture, and they can also impact how quickly that ink dries.

So common ink solvents include water, but also organic substances like alcohols.

For instance, a ballpoint pen tends to use an ink that has an alcohol-based solvent because it dries quite quickly.

Whereas designs and boxes that will contain food tend to use inks with a water-based solvent because it's far safer to keep the food in there then.

Now, you may recall that the boiling point of water is 100 degrees celsius.

The other components then of a water-based ink will boil around about the temperatures of 150 to 290 degrees Celsius.

Now because each of these components have a unique boiling point, we could use distillation to separate the water solvent from the rest of the components.

And because the water solvent has the lower boiling point, it would therefore boil first, and that would make the water, the distillate, from this process of distilling a water-based ink.

Let's stop here for a quick check.

"What method is used to separate the components of an ink?" Well done if you said D.

Distillation can be used to separate those components of an ink.

So that's a great start to this part of the lesson guys, keep it up.

So let's try another quick check.

True or false.

"When conducting distillation on a water-based ink, the pigment is the distillate." Well done if you said false, but which of these statements best justifies that answer? Well done if you said A.

Water will boil first when distilling a water-based ink, water doesn't tend to be found in an ink that is alcohol-based.

So very well done if you manage to get those correct, guys.

Great job.

Let's move on to the next task in today's lesson.

Now, some students are discussing ways in which they might be able to obtain more water from distilling a sample of ink.

I'd like you to discuss how their suggestions might or might not help them to achieve that goal.

Now, Aisha suggests that they swap the test tube rack for an ice bath.

Jun suggests that they turn the Bunsen burner up so that the mixture is being heated more strongly and gets hotter, whereas Sofia suggests about wrapping a cold cloth around that delivery tube.

So pause the video whilst you maybe discuss your ideas with the people nearest you, jot down your answers and come back when you're ready to check your work.

Okay, let's see how you got on.

Well, if you look at 'em a bit more closely, Aisha and Sofia are both suggesting something very similar.

Using an ice bath and wrapping a cold cloth around the delivery tube will help to cool the gas component causing condensation to occur and a liquid to then be produced.

Jun's suggestion isn't as useful because by rapidly heating that mixture, you could actually cause more than one substance to boil, in which case, you're not actually separating the components out, you're just causing several of them to boil at the same time, and you'll actually end up with a contaminated distillate.

So very well done if you manage to suggest any of those ideas about why they might be good or bad for improving this distillation process.

Great job.

For the next part of this task, I'd like you to use a suitable setup to separate the water component of an ink mixture using distillation.

Now, which setup you use will depend on the equipment that's available to you.

And once you've carried out that distillation, I'd like you then to reflect and comment on the effectiveness of your distillation.

How might it have been improved? Perhaps consider some of the difficulties you encountered and how you overcame them, or you could even consider what you need to do to ensure that it's carried out safely.

So pause the video and come back when you're ready to check your work.

Now, if you don't have access to the appropriate equipment needed to carry out the distillation of an ink mixture, you can instead watch here a demonstration of each distillation setup, carrying out that distillation.

So we've set up our inky mixture in a conical flask and place it on top of a tripod and gauze, and I've been heating it with a Bunsen burner below and it's at boiling point.

We can see that because of the bubbles within the inky water mixture.

The conical flask is then given a little bit extra support by attaching it to a clamp emboss, which is then attached to a clamp stent that is out of picture.

Now, as the mixture boils, we can start to see little bubbles being pushed into the delivery tube just above where that clamps then is attached.

And what that is, is actually the gas being pushed into that delivery tube, and as that gas gets pushed further and further away from the heat source, we can see it condensing as it drips down into the other container, which in this case is a test tube, which is inside an ice bath in a plastic beaker.

The first thing we're going to do using the other setup is to pour some of our inky water solution into the round bottom flask.

And when it's all set up, it looks like this.

What we'll notice is there's a tube from the tap that connects all the way the bottom of our condenser, and then another tube that runs from the top of the condenser down into the drain.

And that's because that's turned on to create that cold water jacket.

So once the water is turned on, it will be left on, and then the water pumps into the bottom of our condenser and it's being pushed to the top of the condenser, and we can see some bubbles forming.

Those are air bubbles and what we want to do is make sure those are completely gone to make sure we have that constant cold water jacket supply, and that water will be running throughout the whole process.

We turn on our heating mantle, which acts as our Bunsen burner in this case, so it's heating up then our mixture from the bottom, and then we can monitor the temperature using the thermometer that's been attached.

So at the moment, at around 20 degrees, and as it starts to heat, we see a little bit of bubbling.

We can see a little condensation happening in that first part of the tube, and double checking our thermometer, it's now up to around about 30 degrees Celsius.

Now that we can see far more bubbles popping here, we know that boiling is occurring as we take a closer look at that inky water mixture, more condensation is taking place or looks like in that first bit, and we are now up to around about 55 degrees Celsius and rising.

As we finally reach near 100 degrees Celsius, we can start to see the condensation has moved now into that condenser and the water drips to the end where we can see our clear colourless distillate being collected.

Okay, let's see how you got on.

Now, if you were able to successfully carry out distillation, you should have produced a clear and colourless sample of a pure distillate, which was the water.

If it has any slide of colouring to it, it is more likely that it has been contaminated even by a little bit.

And the easiest way to check that is to hold your distillate sample against something white, perhaps a white tile, something like that, and if you can see any coloration, then it is mildly contaminated.

Getting a pure distillate can be quite tricky and it requires careful control of heating that initial mixture, but incredibly well done if you manage to produce that clear colourless distillate sample.

The next thing I asked you to do was to comment on the effectiveness of your distillation, and that's gonna vary for each individual, group, the equipment setup, everything like that.

But some things that you may have considered if you were using a simple distillation setup, like shown in the picture here, is perhaps using an ice bath or wrapping that delivery tube in a cold cloth, or you may have needed to move or adjust the heat on the Bunsen burner throughout the distillation process in order to reduce the possibility of contaminating the distillate.

Now, this is a particular tricky aspect of distillation, is monitoring the amount of energy that's being transferred into that mixture in order to boil it without potentially contaminating your distillate.

This is a tricky task that actually becomes easier the more frequently you do it, but you will become more confident using this equipment as you carry on in your science career.

So don't worry if you did create a contaminated sample to start with, practise makes perfect and we will get there.

So well done for at least having a go, and being able to consider ways that you could improve how you carry out this practical the next time.

Well, well done.

Wow, we have gone through a lot in today's lesson.

So let's take a moment to just summarise what we've managed to learn.

Well, we learned that some mixtures can be separated into their components using that technique of distillation, and that simple distillation setups whilst commonly used, do have limitations regarding their effectiveness and their safety, and that lost gaseous product can be very hot.

It actually could be a safety hazard.

So we need to be considerate of that if using a simple distillation setup.

Appropriate equipment should be used for distillation.

For instance, swapping a test tube rack for an ice bath or even better, swapping your delivery tube for a condenser.

And that's to ensure the safety and efficiency of the separation of your mixture in the first place.

And we've finally learned that inks are an example of a mixture of substances that can be separated using distillation.

I hope you've had a good time learning with me today.

I had a great time learning with you, and I hope to see you again soon.

Bye for now.