Hello, scientists.

My name is Mr. Wilshire.

And in this lesson, we are going to be looking at separating soluble solids from solutions.

The outcome for this lesson is I can describe how to separate soluble solid from a solution.

There are some keywords to consider as we work our way through the lesson.

The first is dissolve, then soluble.

After that, solution.

Next, separate, and finally, evaporate.

Don't worry if you can't remember exactly what some of these words mean, or if this is the first time that you've seen them.

As we progress through the lesson, the meaning should become clear to you.

If you need to recap, you can pause the video now and restart when you've done that.

The first part of this lesson is called recovering solids and filtering.

Lucas went swimming in the sea and accidentally swallowed some water.

(Mr. Wilshire gulps) Here you can see a image of a child swimming in the sea.

Lucas says, "The water tasted salty in the sea.

Oof, why is that?" Why do you think? Have you ever been to the sea and tasted this as well? Did you find that it was particularly salty? Discuss.

Were you able to share some of your ideas? Well, sea water contains dissolved salt.

That doesn't mean that someone has gone along with a salt and pepper set and tried to mix things up.

No, this is a naturally occurring type of salt.

You can't see the salt because the salt is broken down into tiny pieces, and they're far too small to see.

If you had a microscope, you may be able to see it.

You know it's there because you can taste it when you are swimming in the sea.

I wonder why salty though.

There must be a reason for that.

Maybe that's some extra research that you can do to discover why the sea tastes so salty.

Salt is a solid that dissolves in water.

A solid that dissolves in a liquid is called soluble.

That means that it disappears entirely from our site.

Remember though, just because it's disappeared from our site doesn't mean that it isn't there.

It's just broken down into much smaller pieces, pieces that you'd only be able to see really with a microscope.

Lucas says salt is soluble in water.

So when a solid dissolves in a liquid, this makes a solution.

So solid salt and water mixed together equals a salt solution.

Seawater is one type of a solution.

Lucas wants to prove to his family that salt is dissolved in seawater even though you can't see it.

Is there a way that he can do this without a microscope, I wonder? Lucas teacher says that scientists don't taste things when they're investigating.

Yuck, no, that would be rather unhealthy and especially bad if they go licking things that might be bad for them or poisonous.

So how could Lucas prove that salt is dissolved in seawater? We know that a microscope is one way, but how else can he prove this? Discuss.

Lucas says, "I've learned about filters, and that they can separate some solids from liquids.

Could I sieve the sea water to separate the solid salt grains? I think the water will travel through the holes in the sieve." Would this work? What do you think? Is the water going to travel through the holes in the sieve this way? Discuss.

So what did you think? Is Lucas going to be able to sieve the sea water to separate the salt from the water? Unfortunately, in this case, no.

Sieving doesn't separate salt from sea water.

The salt stays mixed in the water and falls through the holes in the sieve.

The children think about other types of filters that they could use instead.

Sam says, "We could use filter paper to separate salt from seawater.

The holes in filter paper are much, much smaller than the holes in a sieve, so the salt will be trapped." Lucas says, "Yes, I think filter paper will separate salt from water because solid salt can't travel through solid paper." What do you think? Are they both correct here? Is this going to work? Pause the video and discuss.

Restart it when you've done that.

Great discussing, everybody.

I wonder if you were able to consider whether filter paper is the right thing to use here or maybe you've already decided on what is going to work and what isn't going to work.

Ultimately, the end goal here is to find that salt that's dissolved inside the water to make sea water.

Stop and think.

A solid dissolved in a liquid becomes a what? Is it a soluble, a solution, a mixture, or water? The correct answer here is b, solution.

A solid dissolved and a liquid becomes a solution.

So here is task A.

Lucas says, "I think filter paper will separate salt from water." So we need to test if Lucas is correct or not.

You're going to need to put some salt into water and mix it up.

So dissolve a teaspoon of salt into water to make a solution.

The next step then is to observe whether the salt can be separated from the water using filter paper.

So remember, you're going to need to take your filter paper and fold it in half.

Then you're going to need to fold it into a quarter and make a little cone that's going to fit inside the funnel.

Then you can place a funnel inside the beaker.

And when you are pouring your salt and water solution inside the filter paper, you've got to make sure that none of that water will run down the edge.

It all needs to go into the central part of that filter paper or otherwise we're going to miss out on parts that are going to be leaking down the edge of the filter paper.

So best of luck with this task then.

Do you agree with Lucas here? What do you think? Make sure that you have a good think and predict what you believe is going to happen doing this test.

Do you think that the filter paper will separate the salt from the water? Have a go at this task.

Restart the video when you've done that.

These are the different steps that we followed, so your results that may have been similar to this.

Don't worry if they're not though because you could have had some slightly different things to work with.

It says here, "We couldn't see any salt on the filter paper." You can see the filter paper there.

"So now we don't think that the salt in a solution can be separated from the water using filter paper." Hmm, that's a shame.

It's certainly no reason to give up.

There must be a way that we can get the salt out of this water.

Here's step two.

Have a recap here and group these solids according to whether you think they could be separated from water by filtering.

The examples you've got are stones, sand, salt, sugar, flour, and peas? Are they all soluble or are they insoluble items? You decide.

Then after you've done that, you need to add a sentence to explain why filtering does not work for some of the mixtures.

So group the solids according to whether you think they could be separated from water by filtering.

Best of luck with your task.

Restart the video when you've done that.

Well, done for completing that task.

Here's some answers that you could have had.

Don't worry though, some of yours may be different to these.

I think the solids that can be separated from water by filtering are stones, sand, peas, and flour.

This is because they are insoluble in water.

You may already know some of this information before, especially if you've done similar experiments in the past.

I think the solids that cannot be separated by filtering are salt and sugar.

This is because they are soluble in water.

Now that you've had a good recap as to the different materials that are soluble and insoluble, you might have a better idea as to how else you might be able to separate one item from another.

So that question remains still, doesn't it? Are we able to get the salt out of the water and use it in any way? What do you think? The second part of the session is called recovering solids by evaporation.

Lucas and Sam are looking at the filter paper from when they try to separate salt from seawater.

You can see an example there of Lucas and Sam's filter paper, and it's empty.

Lucas says, "If I observe closely, I think I can see tiny crystals of salt on the filter paper.

You might need a magnifying glass to see that maybe, but Sam says that, "Well, you are incorrect.

The salt hasn't collected on the filter paper.

The dissolved salt has passed through the paper." What? But I thought filters were there to stop that kind of thing from happening.

Hmm, let's find out more.

Well, unfortunately, soluble solids cannot be recovered from solutions using filtering.

When a solid dissolves into a liquid, it breaks down into tiny, tiny pieces that can't be seen at all.

These tiny pieces are going to be able to travel through a filter.

So here you can see an example of someone filtering a solution, very similar to what you've done.

They've got their funnel in the top.

They've got their filter, which they've coiled up to create the little cone to go down inside.

Then you've got the solid dissolved in the liquid, going down into the flask or beaker below.

Then the solid dissolved in liquid is still the same below.

It can't really be filtered in the same way.

So how can we separate the salt from the water? There must be a way to get the salt back.

We can taste that the salt is there, but we can't see it.

So how can we separate it? Discuss.

Restart the video when you've done that.

I wonder what kind of ideas you came up with.

Is there a way that we could do this with a different type of filtering, maybe? Let's find out more.

But first, let's stop and think.

Match the type of solids to whether it can be recovered by filtering.

There you have soluble and insoluble.

One of them can be recovered by filtering, and the other one cannot be recovered by filtering.

The answers here are on the screen.

If something is soluble, it can't be recovered by filtering.

If something is insoluble, it can be recovered by filtering.

Remember, soluble means that it was able to dissolve, so there really is nothing left.

It's turned into much tinier, tinier pieces that you can't see.

Insoluble means that this process hasn't happened.

You are still able to see the item that's there, usually collected on the top of the filter paper.

Sam says, "Well, I remember my beach shoes had a puddle of seawater in them.

And when they dried, I could see tiny little salt crystals left behind where the water had been." So here's Sam's beach shoes containing a puddle of seawater.

There's Sam's beach shoes again, and there is a salt crystals.

Oh yes, I can see.

It's definitely not sand, it's salt.

So what happened? Discuss.

Restart the video when you've done that.

So what's happened in this case? How come the salt crystals are there? In Sam's shoes, the water had evaporated from the salt solution, leaving just the salt behind.

And Lucas says, so could we evaporate the water to separate it from the salt? Soluble solids can be recovered from a solution using evaporation.

Sam says, "Well, I can't remember what evaporation is.

How do you do it? Do you know?" Talk to a partner now and discuss, how do you do evaporation? Restart the video when you've done that.

So how does evaporation work? How can you make sure that something has evaporated? Sam says, "Is evaporation where you let the solid settle to the bottom of the liquid?" Lucas says, "Is evaporation where you pour the water away from the solid?" Do you know what evaporation is? Are either of these two correct? Discuss.

Evaporation is when the liquid in a solution changes into a gas and leaves the original solid behind.

So neither of those children were correct really.

So here you can see the salt solution in a beaker.

You can see the gas, which is the water vapour in the air, and then the solid salt.

So by allowing the water to heat up, it's then able to start evaporating and rising into the air.

Liquids evaporate more quickly when they're heated in this way.

So lighting a small fire or using something in the classroom that's going to heat up the beaker is going to help the water to evaporate quicker.

Water evaporates in nature as well.

This is why puddles dry up and washing dries on the line.

There you can see some examples of puddles evaporating and water evaporating from washing as well.

This isn't something that we can really observe with our eyes happening right in front of us.

It's something that takes a little time.

The only way that we know that this process has happened is that the washing is dry or that the puddles have gone.

Stop and think.

How can you recover soluble solids from a solution? Is it by filtering, sieving, settling, or evaporating? The correct answer here is evaporating.

You can recover soluble solids from a solution by evaporating.

Lucas says, "If we heat the salt solution safely, the water will evaporate and the salt will be left behind." Sam says, "I think the salt will evaporate too." What do you think? Are either of them correct? Discuss.

So what did you think? Are either of those children correct there? When the liquid in solution evaporates, the original solid is left behind.

The children would like to try to recover salt from a salt solution using evaporation.

They decide to heat the salt solution so that the water evaporates more quickly.

Sam says, "We could boil it on a cooker." Izzy says, "We could use an oil burner." Lucas says, "We could leave it on a heater." And Andeep says, "We could leave it outside in the sun." Which of these do you think is going to be the best way of doing this? The children ask an adult to help them to work safely because this is an example of an experiment that could be very hot.

To begin the evaporation, they pour a small amount of salt solution into the top of the oil burner and they light the candle.

You can see there the water vapour rising out of the top, the salt solution in the well, the oil burner below, and a candle to provide the heat underneath the well.

They observe what happens and record their observations in their notebook.

Remember, this isn't something that you can see happening right in front of you, but you can speed it up by using a candle and heating it up more in this way.

So let's stop and think, what happens during evaporation of a salt solution? Read these statements and decide which one best matches.

The correct answer here is c, the liquid water changes into a gas and leaves the salt behind.

Here's your final task.

You need to use evaporation to recover salt from water.

You could try the method on the next slide or you could plan your own method.

Record your observations as notes.

Step two of this is to try separating other soluble solids from solutions using evaporation, sugar in water, for example.

So you could recover a salt from a salt solution like this by using the oil burner method.

You pour a small amount of salt solution into the top of an oil burner, you light a candle.

Or you continue heating until the water bubbles, then blow out the candle and let it cool.

Have a go with this experiment.

Remember to be incredibly careful when you're using these hot items. Restart the video when you've done that.

Here's an example of how the results could have been.

It says, "We put a tablespoon of salt solution in a warm, sunny place and left it until the water had evaporated.

The water evaporated, and we could see the salt crystals left in the saucer.

We also managed to do this with sugar solution to recover sugar crystals.

So they've done something in a slightly different way.

They've left it out in the sun to evaporate over time.

If you were to lie to a fire or a heat source underneath, it's going to speed up the process.

And you can clearly see there the crystals that are on the saucer left over and left behind.

Let's summarise our lesson.

A solid that dissolves in a liquid is soluble.

This makes a solution.

Soluble solids cannot be recovered from a solution using filtering.

Soluble solids can be recovered from a solution using evaporation.

Evaporation is when the solution is heated, the liquid changes into a gas, and leaves the original solid behind.

And during evaporation, liquid water changes to invisible water vapour or gas in the air.

Well done for completing those two tasks.

Hopefully, you might go on to use some of these skills in some science experiments of your own.

I wonder what other solutions you can evaporate to reclaim the lost items that have put in at the beginning.

Well done for completing your tasks.

I've been Mr. Wilshire.

Thank you very much for listening.