Lesson video

Hello, everybody! My name is Miss Couves.

It's lovely to see you again.

What have you been doing since our last lesson? I have been in my garden, growing lots of lovely plants.

Today we're going to learn some more about chemistry, which is great because chemistry is my favourite science.

I am so excited for our lesson today, as we're going to do an experiment at the end.

That's why I've got my lab coat ready.

Shall we get started? We're going to start our lesson today by recapping the knowledge from our last lesson.

Then we're going to learn about mixtures and alloys.

And then finally, we're going to do an experiment with oil and water.

You will need an exercise book and some paper and a pencil.

And if you would like to have a go at our experiment, you'll need a glass of water, some oil, and some soap.

You'll also need an adult to help you.

If you don't have these things, you can do the experiment with me instead.

If you need to go and get one of these items, pause the video now, and resume when you're ready to continue.

Let's get ready to recap our knowledge.

Remember to think really hard.

Firstly, we learnt about the three states of matter and how particles were rearranged, were arranged.

Which state of matter had particles arranged in ordered rows? A solid has particles arranged in ordered rows.

Can you point to the diagram of a solid? Which state of matter has particles arranged randomly but still touching? A liquid has particles arranged randomly but still touching.

Can you point to the diagram of a liquid? And which state of matter has particles that are touching and moving very fast? A gas.

Gases have particles that are not touching and moving very fast.

Can you point to the diagram of a gas? Check your answers.

Did you get them right? One of these diagrams shows a pure substance.

Which one? How did you know? The diagram on the left shows a pure substance because it only has one type of particle.

The other shows an impure substance.

How do you know the diagram on the right is an impure substance? The diagram on the right is an impure substance because it contains more than one type of particle.

Today we're going to be learning about impure substances.

Impure substances are also called mixtures because they contain a mixture of particles.

Here are three examples of mixtures, salty water, air, and steel.

Salty water contains a mixture of salt particles and water particles.

Which two particles are in salty water? Salty water contains salt particles and water particles.

Air contains a mixture of oxygen and nitrogen particles.

Which two particles are in air? Air contains a mixture of oxygen particles and nitrogen particles.

Steel is a mixture of iron and carbon particles.

Which two particles are in steel? Steel contains a mixture of iron particles and carbon particles.

How do we know that all of these substances are mixtures? All of these substances are mixtures because they contain more than one type of particle.

How would we represent this on a particle diagram? We would use two different colours.

I'm going to show you the particle diagrams for salty water, air, and steel.

I want you to look at how the particles are arranged and how many different types of particles there are.

How do we know that these are examples of mixtures? We know they're mixtures because they contain more than one type of particle.

When drawing these diagrams, we need to know whether the mixture is a solid, a liquid, or a gas and whether it is a pure substance of a mixture.

Let's have a think about some more examples.

Squash contain sugar particles and water particles.

What state of matter is squash in? How are the particles arranged? How many different types of particles are there? Pause the video, and draw squash as a particle diagram.

Press play when you're ready to continue.

The particle diagram for squash looks like this.

Squash is in the liquid state of matter.

So the particles are touching but arrange in a random order.

There are two different types of particles, squash particles and water particles.

Point to a water particle.

Point to a squash particle.

Pause the video to tick and fix your diagram.

Let's test our knowledge.

We're going to answer these five questions.

I'm going to read you all the questions and then give you time to pause the video to complete them.

Question one, draw a diagram to represent a pure solid.

Question two, draw a diagram to represent a mixture of gases.

Question three, give an example of a solid mixture.

Question four, give an example of a liquid mixture.

Question five, give an example of a gaseous mixture.

That means a mixture of gases.

Pause the video to complete the questions.

Press play when you're ready to continue.

For our pure solid, we should have our particles arranged in ordered rows and touching.

There should only be one type of particle.

In question two, a mixture of gases, our particles should be moving fast and not touching each other.

It's a mixture, so there is more than one type of particle.

So some of your particles should be shaded in.

An example of a solid mixture is steel.

An example of a liquid mixture is salty water.

An example of a gaseous mixture is air.

Pause the video to tick and fix your answers.

An alloy is a special type of mixture that includes a metal.

Metals are usually solids.

How are the particles arranged in a solid? Particles in a solid are arranged in ordered rows, and they're always touching.

How do the particles behave in a solid? They are vibrating on the spot.

Show me a solid.

Great.

The particles in a solid vibrate on the spot.

Bronze is an alloy of two metals, tin and copper.

Look at the diagram.

How do you know that tin is a pure metal? We know that tin is a pure metal because it contains only one type of particle.

Look at the diagram.

How do you know that bronze is an alloy? We know that bronze is an alloy because it is a mixture of metals.

Bronze contains tin particles and copper particles.

Tin and copper are both soft metals, but bronze is very strong.

In fact, bronze was used by humans in the Bronze Age to make tools.

When you mix metals together to form an alloy, they become stronger.

What happens to metals when you mix them together to make an alloy? The alloy is stronger.

Steel is another type of alloy.

It is a mixture of iron and carbon.

Steel is really strong, and it's used as building materials.

Why are alloys more useful than pure metals? Alloys are more useful than pure metals because they are stronger.

How do we know that an alloy is a mixture? We know that an alloy is a mixture because it contains more than one type of particle.

How does the diagram show us that it contains more than one type of particle? The diagram shows this because some of the particles are shaded in and some aren't, to represent different types of particle.

What is the benefit of an alloy over a pure metal? Alloys are stronger than pure metals.

White gold contains gold particles and platinum particles.

What state of matter is white gold in? How are the particles arranged? How many different types of particles are there? Pause the video, and draw a particle diagram for white gold.

Press play when you're ready to continue.

What do the particles in white gold look like? White gold is a solid, so the particles are touching and arranged in ordered rows.

How are the particles, how many different types of particles are there? There are two types of particles, gold particles and platinum particles.

Point to a gold particle.

Point to a platinum particle.

Pause the video to tick and fix your answers.

Press play when you're ready to continue.

Let's test our knowledge by answering these four questions.

I'm going to read you the questions.

Then you can pause the video to give you time to answer them.

Question one, what is the difference between a pure metal and an alloy? Question two, which metals make the alloy bronze? Question three, how is bronze different from pure metals? Question four, how do you know that bronze is a mixture? Question one, a pure metal contains only one type of particle, whereas an alloy is a mixture of different types of particles.

The metals that make the alloy bronze are tin and copper.

Question three, bronze is stronger than pure metals tin and copper.

Question four, bronze is a mixture because it contains two different types of particle.

Pause the video to tick and fix your answers.

Press play when you're ready to continue.

We're going to investigate mixing with two different substances, oil and water.

If you would like to have a go at the experiment, you will need some oil, some water, some washing-up liquid, and a spoon.

If you don't have these items, you can do the experiment with me.

If you would like to do the experiment, you need to make sure there is an adult to help you.

Pause the video now, and go and get them.

I'm wearing my lab coat because this experiment can get a little bit messy.

You might also want to wear something to protect your clothes.

We're going to look at the mixing of oil and water.

I have two liquids, oil and water.

Let's see what happens when I mix them.

That's interesting.

The oil floats on the top.

Can you see that? The two liquids are still separate.

They didn't mix.

Did that happen in your experiment too? Let's try giving them a stir, and see what that happens.

They still don't mix.

The oil is still at the top, and the water is still at the bottom.

These two liquids, oil and water, don't mix.

There is a special scientific word for liquids that don't mix.

These liquids are called immiscible.

My turn.

Immiscible.

Your turn.

Good pronunciation.

These liquids don't mix.

They are immiscible.

What do we call two liquids that do not mix? Immiscible.

Now let's see what happens when we add some washing-up liquid.

Before I add the washing-up liquid, the oil and the water do not mix.

Which scientific word can I use to describe that? Oil and water are immiscible because they don't mix.

Now I'm going to add some washing-up liquid.

Let's see what happens.

Give it a stir.

Can you see what's happening? The oil and the water are now mixed.

We've not got two separate layers anymore.

Liquids that mix are called miscible.

My turn.

Miscible.

Your turn.

What do we call two liquids that do mix? Miscible.

Isn't it interesting that oil and water don't mix by themselves, but they do mix when we add washing-up liquid? That's why we need to use washing-up liquid when we clean our pots and pans.

The washing-up liquid makes the oil and water miscible so that we can remove it from the pan.

Next time you're washing up, you can explain that we use soap to make the oil and water miscible.

Isn't that interesting? Let's practise.

Why do we have to use soap when we're washing up? We use soap when we're washing up to make the oil and water miscible, so we can remove it from the pan.

What did the word miscible mean? Miscible means that two liquids can mix.

Great.

Let's recap our knowledge.

You have four questions to answer.

I'm going to read them to you and then give you time to pause the video.

Question one, what happens when you mix oil and water together? Question two, what is it called when two liquids do not mix? Question three, what happens when you add soap? Question four, what is it called when two liquids do mix? Pause the video, and answer the questions.

Press play when you're ready to continue.

Question one, oil and water do not mix.

There is a layer of oil on top of a layer of water.

Question two, two liquids that do not mix are called immiscible.

Question three, when soap is added, the oil and water mix together.

They are no longer in separate layers.

Question four, two liquids that can mix are called miscible.

What an exciting lesson that was.

It is great when we learn things about the world around us.

Isn't it? Make sure you have a go at the quiz to recap your knowledge.

See you next time!.