Welcome to today's lesson.

It's a practical lesson looking at red cabbage indicator solution and it's part of the unit, Acids and Bases.

My name's Mrs. Miam Smithson and I'm so pleased that you've come along to learn with me today.

Today, we're going to look at making red cabbage indicator solution and then using it to test solutions to find out if they're acidic or alkali.

Today's keywords are pestle and mortar, chemical indicator, pH scale, universal indicator, solution.

On the next slide there's these keywords in some sentences, so pause the video if you wish to read them.

Then press play when you're ready to start the lesson.

Today's lesson consists of two learning cycles.

Firstly, making an indicator and then testing indicators.

So let's get on with the lesson.

Let's look at making an indicator.

Many brightly coloured flowers, fruits, and vegetables contain chemicals called colourants, and they can change colour in different pH solutions.

So here's some flowers here.

Hydrangea flowers are different colours depending on the pH of the soil that they're growing in.

Some flowers, fruits, and vegetables can have their colourants extracted and used as an indicator to test acidic or alkaline solutions.

A quick check for understanding now.

True or false, indicator solution can be made from flowers? Is that true or is that false? Pause the video, decide, and then when you're ready for the answer, press play.

Well done if you said true, indicator solution can be made from flowers.

Now on to justification.

Is it that the colourants from all flowers can be made into a solution that changes colour if mixed with acids or alkalis? Or is it that the colourants from some flowers can be made into a solution that changes colour if mixed with acids or alkalis? Pause the video while you decide and then press play and I'll tell you if you're right or not.

So well done if you said the colourants from some flowers can be made into a solution that changes colour if mixed with acids or alkalis.

So not all flowers have these colourants that can change colours if mixed with acids or alkali.

Well done if you've got that one right.

Which vegetable or vegetables is or are likely to be a good indicator? So we're looking at these images.

Which one or ones are going to be a good indicator? Pause the video while you decide and then press play and I'll give you the answer.

So well done if you said A and C.

They're brightly coloured, so they're likely to be a good indicator.

The mushrooms don't have any colour in them, so they're not likely to be a good indicator at all, 'cause we couldn't see a colour change.

So well done if you got that one right.

In order to make an indicator from red cabbage, you will need some chopped red cabbage, a mortar and pestle.

So the mortar's this bowl, and the pestle is the kind of club-shaped instrument that you grind with.

You might have seen these at home.

A stirring rod; so this is a bit of glass or plastic used to stir things in science.

Hot water from a kettle and a beaker.

And then we've got this filtration equipment.

So we've got the filter paper that fits inside the funnel and the funnel then fits inside the conical flask.

So it's called a conical flask 'cause it's shaped like a cone.

And here's how you fold your filter paper.

So you fold it in half, first of all, then you fold it in half again, and then you open it up to find a little pocket and pop it in the top.

Let's watch that again.

Fold it in half, fold it in half again, open it up.

There you go, you can see, place it in.

That's our filtration equipment.

The method for making a red cabbage indicator is as follows.

The first thing you need to do is crush the chopped cabbage pieces for two or three minutes using a mortar and pestle.

So you're going to use that pestle to grind the red cabbage until it's all mushy.

You're going to then transfer this crushed cabbage to a beaker.

You're going to pour hot water from a kettle until it covers the crushed cabbage.

Now it needs to be hot, but it doesn't need to be boiling hot.

You want to really add just enough to just cover it.

If you add too much water, you're going to make an indicator that's pale in colour and it will be difficult to see the colour changes.

Then what you're gonna do is you're gonna stir the cabbage and water mixture with a stirring rod for around two minutes until the water changes to a deep purple colour.

So you should be stirring this and looking at the colour change in the water.

Then you're going to use your filtration equipment.

You're going to filter the cabbage and water mixture, and you're going to keep the coloured water.

And this coloured water is now called your red cabbage indicator.

A quick check for understanding now.

Which is the best volume of water to add to the red cabbage to make an indicator? Is it a little bit, a middle size bit, or a lot? Pause the video while you decide and then press play when you've got your answer.

Well done if you said A.

You just need to cover that red cabbage with the hot water.

You don't need to put a lot in because if you put a lot in, you're going to make a very pale-colored indicator solution.

So you want to go as deep as possible.

So just cover that red cabbage with the water.

Well done if you got that one right.

Which equipment is used to separate the red cabbage pieces from the red cabbage indicator solution? Is it A, B, or C? Pause the video while you decide, then press play and I'll tell you if you're right or not.

Well done if you said A.

This is filtration equipment, so it consists of a conical flask with a funnel and some filter paper inside of it.

You're going to pour the red cabbage pieces and the solution in the top and out of the bottom of the funnel, you're going to get the red cabbage solution.

So the red cabbage indicator solution is going to be in the conical flask and all the pieces of red cabbage are going to remain in the filter paper.

B was just a kettle and C was a mortar and pestle that you are going to grind your red cabbage to smaller pieces.

So let's see what you think here.

Which are the best size red cabbage pieces to make an indicator with? Is it A, B, or C? Choose your answer and then press play and I'll let you know if you're right or not.

So well done if you said C, you want it chopped as small as possible so we can get as much colour out of the red cabbage as possible.

So well done if you've got that one correct.

Here's another check for understanding.

Why should you take care not to add too much water to the crushed cabbage? Will it be that the indicator solution will be too deep in colour, will the indicator solution be too pale in colour, or will the indicator solution be too reactive? So pause the video, decide on an answer, and then press play and we'll go through it together.

So well done if you said if you add too much water to the crushed cabbage, your indicator solution will be too pale in colour.

Now, here's task A.

What I want you to do now is match the equipment to the image and description.

So here's the equipment, here's the name.

So we've got funnel, pestle, conical flask, mortar, stirring rod, and filter paper.

And then we've got descriptions of where the filter paper is placed for filtration, the bowl where the red cabbage is crushed to make smaller pieces, used to stir the red cabbage and water mixture, used to crush the red cabbage to release the colourant, used to separate the crushed cabbage from the coloured solution, and this is where the coloured solution is collected.

So pause the video, match up the equipment, so match up the pieces of equipment to those names and then to the description.

Well done, let's go through the answers now.

So we've got a funnel and then we've got the pestle there, the conical flask, the mortar, that's the bowl, the stirring rod, and finally the filter paper.

Now we're going to have a little look at the descriptions there.

We're going to match those up.

So the funnel, that's where the filter paper is placed for filtration.

The pestle is used to crush the red cabbage to release the colourant.

The conical flask, that's going to be where the coloured cabbage solution is collected.

The mortar is the bowl where the red cabbage is crushed to make smaller pieces.

The stirring rod is used to stir the red cabbage and water mixture.

And finally, the filter paper is used to separate the crushed cabbage from the coloured solution.

So well done if you've got all of those correct.

What I'd like you to do now is write a method.

So you're going to write a five-step method for making indicator.

I want you to use the images to help you.

I want you to write a step for each image there and what it shows.

So pause the video, once you do that, then press play and we'll go through the answers together in a minute.

Well done for completing that task.

Let's see if your method is similar to mine.

So using a pestle and mortar to crush the red cabbage, you're going to crush that for two or three minutes.

Then, you're going to place a crushed cabbage into a beaker.

You're going to cover the crushed cabbage with hot water.

Stir the crushed cabbage and water mixture for two minutes.

Filter the cabbage mixture and keep the coloured solution.

So that's our five-step method.

Your words might not exactly match, but you should have mentioned the equipment and what you would do with it in each step.

Well done for completing that task.

So part three of task A, this is the fun bit now.

You're going to carry out the practical to prepare your own indicator solution.

So prepare your indicator solution and then press play when you've done that.

Well done for making the indicator solution.

You should have some red cabbage indicator solution that looks similar to this.

So the deeper the purple colour, the better the red cabbage indicator solution.

This is one that I made.

I wonder how deep yours is compared to mine.

We've completed our first learning cycle and made an indicator.

Now we're moving on to testing indicators.

Indicators can be tested by adding them to a range of different solutions, then observing any colour changes.

So to test some indicators, you are going to need a range of solutions at different pH levels and some different indicators.

So you might choose some red and blue litmus paper, red cabbage solution that you've made earlier, and some universal indicator solution or some universal indicator paper, whatever you are provided with.

You'll also need a pipette and a spotting tile.

Here's the method that you're going to use to test your indicator.

Firstly, you're going to place three or four drops of each pH solution in the wells of the spotting tile.

So here's us putting the solutions of different pHs.

You'll obviously need to remember which ones which pH.

Then what you're going to do is you're going to add indicator solution, so two or three drops of indicator or indicator paper to the well.

Then you're going to record the colour of that solution.

Then you're going to repeat it for all the other pH solutions and all the other indicators until you've got a full set of results.

A quick check for understanding.

Which piece of equipment is used to place the solutions and indicators into the spotting tile wells.

Pause the video while you have a think, then press play, and I'll go through the answer with you.

So well done if you said B.

B is a pipette and pipettes are used to transfer solutions from one place to another.

What should you record in your results table? The number of drops of pH solution being tested placed in the well of the spotting tile, the number of drops of indicator solution placed in the well of the spotting tile, only the colour of the solution before the indicator solution or indicator paper is added, or only the solution or indicator paper after the indicator solution or indicator paper is added.

Pause the video and then press play when you've got your answer.

Well done if you said only the colour of the solution or indicator paper after the indicator solution/ indicator paper is added.

Well done if you got that one right.

What I want you to do now is carry out the practical following instructions from your teacher to compare different indicators.

So the indicators, they're in the left-hand column there.

So we've got red litmus, blue litmus, universal indicator, and red cabbage.

And then you are going to record the colour of the indicator when it's placed in different pH solutions.

So pause the video while you carry out the practical and then press play and we'll go through some results together.

Your results might look similar to these.

So red litmus, it should be red in acid and pH7, and in alkaline it should be blue, so it should be blue.

And then the blue litmus, again, that should be red in the acid.

It should be blue at pH7 and at pH9 and 11, those alkalis, it should be blue.

Universal indicator should go from orange to yellow to green to light blue to dark blue as you go up through the pHs.

And red cabbage, maybe a pink colour at pH2, a pink colour at pH4, a purpley colour at pH7, a greenish colour at pH9.

At pH11, it will also be a greenish colour.

So well done if you've managed to complete that practical and got similar results to mine.

What I want you to do now is write a conclusion for your indicator experiment.

Which indicator or indicators do you think give the best results in this experiment and which one or ones were the least effective? So we've got some sentence starters to help you.

So the best indicator or indicators were, and then you're going to write the name of it there, and then you're going to tell me the advantages of using it or them.

Then the least effective ones, and you're going to tell me the disadvantages of using them.

So pause the video, once you do that, then press play and we'll go through the answers together.

Well done for completing your practical.

Your conclusion might be similar to this.

So the best indicator was the universal indicator and the advantage of using it, it was easy to see all the different pH solutions as each had a different colour.

So you could have said that it had a large colour range.

As long as you've got something that says that each pH has got a different colour, then that's correct.

Now, for the least effective indicator, here's a reason that you might have chosen red or blue.

So the disadvantage was that for the red litmus, you can't tell the difference between neutral, which is pH7, and acidic solutions.

And for the blue litmus, you can't tell the difference between pH7 and the alkaline solutions.

You might have said that there were just limited colours, so it was either red or blue and there was no range of colours.

Or you might have said that the least effective indicator was the red cabbage.

So you might have said that you couldn't tell the difference between the acidic solutions and the alkaline solutions.

So, so long as you've got something that sounds similar to these, then you've got it right.

Well done.

Here's a summary for today's lesson.

Red cabbage solution is pink or red in an acid, purple in a neutral solution, and green in an alkali.

Universal indicator will turn many different colours depending on pH.

Different chemical indicators have their advantages and disadvantages.

Well done on working really hard this lesson to make an indicator out of red cabbage and then testing it and comparing it to other indicators.

I hope you've enjoyed this lesson and we'll come back soon.