Hello, my name's Mrs. Niven, and today we're going to be looking at separating out mixtures and talking about formulations as part of our discussion of separating substances.

Now, you may have some experience of separating mixtures from previous learning or some of your experiences outside of the classroom, for instance, in perhaps car mechanics, or cooking, or in art, all sorts of things.

So we'll be able to take some of those experiences into our lessons going forward.

But what we learn in today's lesson will also help us to think about as a chemist, how can we consider the mixtures that we encounter to separate out, a substance we might want or need? We'll also be able to use what we learn in today's lesson to answer those big questions of how can we explain how substances behave, and also how we can use that information to describe what substances are actually made out of.

So let's get started.

By the end of today's lesson, you should be able to describe what a mixture actually is and be able to list some methods that you might be able to use to separate them out.

Throughout the lesson, we'll be using a few different keywords and they include mixture, property, formulation, and separate.

On the next slide, you'll see the definitions for these keywords provided in sentence form, and you may wish to pause the video here so you could read through them or perhaps make a note of them, so you can refer back to them, later on in the lesson.

In today's lesson, we'll be looking at two main things.

Firstly, we'll look at mixtures and then we'll look at how we can separate those mixtures.

So let's get started by talking about what a mixture is.

Now many of the starting materials that chemists work with on a regular basis are actually found in nature, and those materials tend to exist as mixtures in nature.

So a lot of the materials that chemists might use could come from rocks, it might start as part of the sea water, or it could even be found in air.

Now the thing to remember though is that a mixture is a material that contains two or more different substances, and those substances could be elements and, or compounds, but crucially, those substances are not chemically bonded together.

So when we take a closer look at rocks, they tend to be a mixture of many minerals, and some of those minerals may actually include some useful metals.

So the materials we might want to separate from this mixture could include some of the materials you might find in electronics, like your mobile phones, things like that.

In sea water, it's actually a mixture of the salt and the water.

Anybody who's ever gone in the sea and accidentally got some in their mouth, will be able to taste the salt.

But, being able to separate this particular mixture out, we'll be able to use water that we can help to hydrate ourselves, and also salt that might be able to use to preserve or flavour food, so it's useful to separate this mixture.

And air, for instance, is actually a mixture of lots of gases and they include things like argon, water vapour, nitrogen, carbon dioxide, and oxygen.

And there's many other gases that are still in the air, but these tend to be the ones that are there in the largest proportions.

Let's pause here for a quick check to see how you're getting on.

Which of the diagrams below shows a mixture? Well done if you said b, c, and d.

All three of those show a mixture.

And the reason they show a mixture firstly, is because they have two different substances within those diagrams, and we can see that by the different colours.

Secondly, we can see that they're not joined together.

They may look like they're joined together, but they're not overlapping and therefore, they're not chemically bonded together and could potentially be separated from each other.

Well done, if you managed to get those three correct.

So a quick and easy way to distinguish if the substance you're looking at is pure or a mixture, is to consider the temperature that it changes state of matter.

For instance, a pure substance would change state at a very definite temperature, like water boils if it's pure at exactly 100 degrees Celsius, and it would melt at 0 degrees Celsius.

So if we are looking at these two samples over the bunsen burners in the picture here, pure water on our thermometer then, would boil at 0 degrees Celsius, whereas sea water, which is a mixture of salt and water, would probably boil closer to, 102 to 123 degrees Celsius.

Mixtures, on the other hand, tend to change state over a range of temperatures.

For instance, whilst pure gold, that's 24 carat gold, would melt at 1064 degrees Celsius, a mixture of metals, so probably an alloy, for instance, here we've got rose gold, which is a mixture of gold and copper that would melt anywhere between 1000 and 1100 degrees Celsius.

Let's stop here for another quick check.

Which of the following would help a chemist decide if a sample is a pure substance or a mixture? You may wish to pause the video here, so you can read through and discuss your options and then come back when you're ready to check it.

Well done if you said d, the temperature at which a substance melts, would help a chemist decide if a substance is pure or a mixture.

We could also look at whether or not the temperature at which it boils.

A doesn't really work because if substances are mixed to make it, it might have actually resulted in a chemical reaction.

Likewise, for c, what happens when it's added to water could tell us whether or not it reacts or not, and that's not really gonna give us a good indication of whether or not it's pure or a mixture.

Neither will it tell us, if it's natural or man-made will help us.

Really, we need to look at its physical properties, and that is its melting or boiling points.

So well done if you answered d.

Now, some mixtures are better known as formulations, and a formulation is simply a designed mixture, and that means that each part or each component within that mixture has a very specific purpose to play in the final product.

And an example then is medicines.

In a medicine, you are likely to find an active ingredient, the drug that is being delivered as part of that medicine, be it to relieve your headache or perhaps aches and pains in your joints or an upset stomach.

It might have some flavouring in it.

You see this most likely in children's medicines, black current, orange, strawberry, to make it easier for them to ingest, more willing to take their medicine.

It might have a binding agent to keep it in its tablet form so it doesn't disintegrate when you take it out of its packaging.

Maybe it has some colouring so that you can tell one tablet different from the other if they're of similar size and of shape.

And finally, it might have a stabiliser to make sure that everything does its job and stays as it should be until it's actually taken by the patient.

So each of these different components, makes up the one mixture, the medicine, but each part of it plays a very specific role within that mixture.

Now, most of the products that you come across on a daily basis are most likely going to be formulations, and you'll find them in all parts of life.

Some examples include health and beauty care products.

So we've got a toothpaste, then we've got some hand lotion, chapstick, mouthwash, body soaps, even hair products will be formulations.

Now, other examples that you might come across as a formulation include foods.

So milk for instance, is a formulation.

If you go down the dairy aisle, you could see whole milk, 2%, semi-skimmed, skimmed milk, and each of these are formulations that have varying degrees of fat and water in there with other ingredients.

The ketchup you might have.

Now, some people might have Heinz, somebody might prefer Sainsbury's own brand, and the difference in the flavourings comes down to the formulation for that particular type of ketchup.

Any milk alternative, so oat milk, almond milk, things like that will be a formulation to provide a particular consistency and flavouring that simulates milk, cow's milk.

Stork, for instance, if you look at the ingredients list, you can actually see parts of the formulation in there.

So it contains emulsifiers, which help to keep the mixture from separating and then also flavourings, so that, you get that when you are baking with it.

Another great example of formulations is paint.

When we're talking about fence paint, we want to make sure that the components are going to work to last with any type of weather it might encounter over the course of a year.

Whereas watercolour paints, we would like them to have slightly different properties.

And the same again with face paint.

Those should be able to rub away quite easily, very different from our fence paint.

And finally, some other products that we might come across that are formulations.

Any protectants you might use for your shoes, any fertilisers for your plants, lubrication that you are using on your bike chains or your door locks, things like that.

And any alloys that you might come across, and that could be jewellery or tin cans, or things like that.

They are all formulated.

So have a very specific components and very specific proportions, in order to provide the properties that are needed within that particular product.

Time for another quick check, true or false.

Useful substances are called mixtures.

Well done if you said false, but which of these statements best explains why? Well done if you said b.

A formulation is a mixture for a specific purpose and those tend to be very useful products.

A compound is simply two or more elements that have been chemically bonded together.

Time for our first task, what I'd like you to do for this part is for each of the diagrams that are shown, I want you to decide if the substance is pure or a mixture.

Once you've decided that, tell me do you think it will have a definite melting point or if you think it will melt over a temperature range.

And then finally, can you tell me, is this displaying an element, a compound, or a combination of both? Pause the video here and come back when you're ready to check your answers.

Okay, let's see how you got on.

So for diagram a, you should have said that it was a mixture, and that's because we can see two or more substances that are not bonded together.

And because it's a mixture, it's going to melt over a temperature range, and what we see here is an element shown by the single pink circles and then a compound, which is the white and blue circles that have been overlapped and therefore are bonded together.

For diagram b, we can see that it's a pure substance because all of the circles in there are the same colour and because it's pure, it's going to melt at a very definite temperature.

And because all of the circles are the same, we can say that it is an element.

For diagram c, we can say that it is a pure substance, and because it's pure, it is going to have a definite melting temperature, melting point, and we can say that it is a compound.

If we look at these, we have always one red element with two of the white elements bonded to it, 'cause they're overlapping.

So each of these units are composed of just one red and two white circles, and so our diagram here is showing that pure compound substance.

Now for diagram d, it gets a little bit more complicated.

I personally would draw circles around the different components that I have, so I can try and keep track of them.

But when I do that, I can see that it is a mixture, and because it's a mixture, it's going to melt over a range of temperatures.

And when I look at them, I can see that I have two different compounds.

One compound is composed of one black and two red circles, whereas the other compound is composed of one red and two white circles, and they are overlapping, so it's compounds.

So that was a really, really tricky task.

I would say give yourself a massive pat on the back if you managed to decide if they're pure or a mixture.

Fantastic work, if you managed to also tell me if it was going to melt at a specific temperature, over a range of temperatures and very large kudos if you were able to tell me if it was an element, a compound, or a combination of both, because that would've relied on you remembering some of your previous learning, so incredibly well done on this first part of task A.

Great job, guys.

Okay, for the second part of task A, I'd like you to first of all use the words in the box to complete the summary about formulations, and then for part b, I'd like you to circle all of the examples of formulations that you can see in that list below.

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

Okay, let's see how you got on.

So for the first part of this question, you were asked to use some words in a box to complete a paragraph summary about formulations.

Now, before we go through this, I would recommend, you actually go back and actually highlight the words that you originally chose.

It makes them easier to find when you're checking your answers, and it also means that you can see really quickly and easily, whether or not you got them in the right place.

As we go through these, always tick it if you get it right, fix it if you got it wrong and fill it in, if you left it blank.

Now, if you put the correct words in the right spots, it should read like this.

Some mixtures have been designed for a specific purpose.

These mixtures are known as formulations.

Much time, energy, and money is spent ensuring components are added in the right proportions to achieve the desired, most useful product.

So well done if you managed to correctly finish that paragraph.

Now for part b, you were asked to circle all the examples of the formulations that were listed.

And if you've done that correctly, you have circled the following formulations.

So sun cream, fuel, fertiliser, paint, and detergent, are all examples of formulations because they all have a very specific job to do and therefore tend to be mixtures with a specific components, in specific proportions to make them useful.

So really well done, if you manage to get at least two or three of those.

A fantastic job, if you got all five.

You guys are doing really well, keep up the good work.

Now that we're feeling more comfortable being able to decide whether or not, a substance is pure or a mixture, let's move on to look at how we might be able to separate mixtures.

Sometimes we come across substances that are mixed together but can't be easily separated.

And a good example of that might be cake batter.

You would put together maybe some flour, eggs, milk, vanilla flavourings, things like that, mix 'em all together, and once that's done, it's very difficult to get the eggs back the way they were or the milk back.

And the same can be said as something like cement, where you have the cement powder maybe mixed with water, some aggregate pebbles, things like that.

They've all been mixed together, but it's very difficult to then separate them completely from each other, once they've been mixed together.

Now in everyday life, you might refer to cake mix that you could find, you can actually get a cake mix box down the bakery aisle.

And we refer to these large trucks that are carrying cement from place to place as a cement mixer.

But when we're talking about a mixture in a chemistry lab, a key feature of the definition of a mixture is that, the different substances that make up that mixture, the different components can be physically separated from each other rather easily.

So the way that we talk about a mixture is very different from real life.

In chemistry terms, cake batter is not a mixture and neither is cement.

So chemistry refers to a mixture as a material made of two or more substances that can be easily separated.

Now those can be easily separated because the individual substances, the individual components of that mixture, retain or keep their chemical and physical properties even when they're in that mixture.

So we're looking at sea water, the water would keep its chemical and physical properties and the salt would keep its chemical and physical properties.

What chemists do is they exploit those properties in order to separate the mixture into its individual components.

Now, in order to do that, the chemist needs to consider the mixture itself, the properties of the individual components within that mixture, and then decide what technique is going to be best used to separate one component from the others in that particular mixture.

So let's look at an example.

The metals, iron, nickel, cobalt, and steel are all magnetic materials, okay? That means, that if I need to remove any of those four metals from a mixture, I could simply use a magnet.

So I've considered the mixture it con-, containing one of those four metals.

I know that those metals are magnetic, so therefore I'm going to use a magnet to remove them from the mixture.

Another property I might be able to exploit in separating a mixture is the fact that a pure substance has a very specific density.

Likewise, substances that are more dense than other materials in a mixture, might sink to a bottom of my container, whereas others that are less dense than other substances in the mixture, could actually float and I'd be able to easily scoop them up, off the top of that mixture.

Meanwhile, some components in a mixture, might dissolve in water or another solvent and others might not, and that would impact on the technique that I'm using, in order to separate that component.

For instance, if I have an insoluble substance, I might use this technique, and if I have a soluble substance, I might use another technique.

Now, another thing a chemist might be able to do, is consider a change of state in order to fully isolate a component.

Now, if that's a consideration, we might need to think a little bit more carefully about the components properties, in order to separate it in the first place, or to ensure that it's completely isolated from the other components of that mixture.

For instance, if I just had one liquid that I wanted to remove from a mixture and isolate in another container, I might use this setup.

But if I had a mixture that contained two liquids and I wanted to fully isolate them into separate containers, I might need to adjust the setup slightly, in order to make sure that it's separated fully.

Let's pause here for a quick check to see how you're getting on.

Which of the following is a property that chemists could use to separate components in a mixture? Well done if you said all of them.

There is an arsenal of properties that chemists can consider and exploit in order to separate out the mixture, which is fantastic.

It means you have a lot of options open to you, in order to pick the best technique for the mixture or component that you're considering.

Let's move on to the last task of today's lesson.

Aisha and Izzy are deciding which properties of iron filings, pebbles and seeds are important when separating them from a mixture.

What I'd like you to do, is to suggest a method for fully separating a mixture that contains these substances.

You'll probably want to pause the video here to consider and discuss your options with the people nearest to you and jot those down and then come back when you're ready to check your answer.

Okay, let's see how you got on.

So one of the first things, you could have thought about doing is maybe adding water to the mixture, so actually adding another component to this mixture.

But there is a reason why.

If you do that, then the seeds would float to the top and you could simply pull them out the top of it.

You could just scrape them off the top of your mixture.

The next thing you might be able to do is to use a magnet then to remove those iron filings from the mixture.

Now, iron filings tend to be quite fine and very difficult to pick up.

So using a magnet would be the best option here.

And the other thing we could think about is the fact that pebbles tend to be quite dense, so they would've sunk to the bottom of our container, and if that happens, the next thing you could do is simply pour the water off the top, or you could maybe pour the entire mixture of the pebbles and water through a sieve, and that might leave the pebbles behind and let the water through, completely isolating all of the components of that mixture.

So lots of options open up to you.

Well done if you manage to suggest even one or two and fantastic work if you've managed to suggest a method that would've isolated all of those different components.

Great job guys, and an excellent start to this topic of separating substances.

Let's summarise now, what we've learned in today's lesson.

Well, we learned that a mixture consists of two or more elements and, or compounds, that are not chemically bonded together.

And that pure substances change state at a specific temperature, whereas a mixture would do so over a range of temperatures.

We also learned that a formulation is a designed mixture, and that each part of that mixture has a very specific purpose in order to create a desired, useful product.

We've also learned that the chemical and physical properties of substances in a mixture are retained, they're unchanged, and chemists can exploit those properties in order to separate the components out of a mixture.

And finally, we've learned that there are many processes that are open to chemists in order to separate out these mixtures.

I hope you've had a good time learning with me today, and to see you again soon.