Welcome to today's lesson on acids and basis.

It's part of the topic acids and basis.

My name's Mrs. Mytum-Smithson and today we're going to learn all about acids and bases, and how to test for them.

By the end of this lesson, you should be able to describe some properties of acids and bases and use litmus paper to test for acids and bases.

Don't worry if you don't know anything about this topic.

We're going to work through it step by step.

Today's keywords are acid, base, alkali, litmus paper, corrosive substance.

On the next slide, there's some sentences that include these keywords, so pause the video if you want on the next slide to have a read and then press play when you're ready to start the lesson.

Today's lesson consists of two learning cycles.

Firstly, we're going to look at acids, bases and alkalis, and then we're going to move on to testing and we're going to look at red and blue litmus paper.

So let's start our first learning cycle, acids, bases and alkalis.

Let's get going.

Edible acids have got a sour taste.

Some food and drink contains edible acids that are safe to eat or drink.

And these include fizzy drinks, fruits, such as lemons, fizzy sweets.

And if we have a look at these fizzy worms and the ingredients on the back of the packet there, we can see that these fizzy worms that taste sour contain three different types of acid.

They contain malic acid, lactic acid, and citric acid.

If we have a look here at this cola drink, we can see on the ingredients listed as phosphoric acid.

So this cola contains phosphoric acid, which gives that sour taste to it, that tangy taste.

However, I must point out at this point that not all acids are edible, so I don't want you going drinking, eating anything that's labelled as an acid, but it would be interesting if you go home and have a look at some of the ingredients of some of the things that you eat that have got a sour taste and see if you can spot the acids listed on the back of the ingredients.

Quick check for learning.

Edible acids have got a sweet taste, sour taste, bitter taste.

Pause the video, select which answer you're going to choose, and then press play and I'll let you know if you're right or not.

Well done if you said that edible acids have got a sour taste to them.

True or false? You can eat all acids.

Is that true or is that false? Pause the video for some thinking time.

Then press play when you've got your answer.

Well done if you said that that was false.

Now I want you to justify your answer.

So you can only eat edible acids.

You can only eat acids in a science laboratory.

Pause the video, have a little think and then press play and I'll tell you if you're right.

So well done if you said you can only eat edible acids.

All the acids in a science laboratory are not safe to eat.

A base is any substance that reacts with acids to form a compound called a salt.

Alkalis are soluble bases and form alkaline solutions.

So copper oxide is a base because it will react with acids to form salts, but it is not an alkali because if you put it into water, it will not dissolve.

It is not soluble in water.

However, sodium hydroxide is an alkaline because it's soluble in water and it forms an alkaline solution.

So it's a base because it reacts with acids to form compounds called a salt, and it's also soluble in water.

So you can have a look there.

Those white pellets dissolved in water produce that solution there called sodium hydroxide solution.

Some acids and alkalis are corrosive and they can cause chemical burns.

So if you can get these on your skin, they can cause irritation and they could even cause a burn, a chemical burn where your skin was be would be destroyed.

So here's a hazard symbol for substances that are corrosive.

So if you see this anywhere, you want to stay away from them because they might cause chemical burns.

Here's some caustic soda.

So this is another name for sodium hydroxide solution.

This is used as a drain cleaner.

So here's a picture of a drain cleaner, and sometimes you can find the hazard symbol on it.

So you can see here just in that circle that that is the hazard symbol for corrosive.

True or false? Some acids are corrosive and can cause chemical burns.

Is that true or is that false? Pause the video while you decide, then press play and I'll tell you the answer.

So well done if you said that that was true.

Some acids are corrosive and can cause chemical burns.

So here we've got two justifications.

Edible acids do not cause chemical burns.

Chemical burns are caused by all acids.

I want you to select one of those answers, so pause the video whilst you do that.

Then press play and I'll let you know if you're right or not.

So well done if you said that edible acids do not cause chemical burns.

We wouldn't add them to our food if we were going to swallow them and cause chemical burns in our throat.

So the acids that you see contained within food are safe and they're edible acids, and they do not cause chemical burns.

Well done if you got that one correct, which is the hazard symbol for corrosive? Pause the video now for some thinking time.

Press play when you've got your answer.

Well done if you said B.

That is the hazard symbol for corrosive.

So anything with that, you want to be very careful with how you use it because it might cause chemical burns.

A is the hazard symbol for pressured gas, and C is the hazard symbol for explosive.

Here's task A.

What I want you to do is help the students to complete the sentences by selecting the correct word or words from the brackets.

So Sophia says, "Edible acids have a sour or sweet taste.

These acids are dangerous or safe to eat and can be found in sweets and drinks.

Laboratory acids should or should never be consumed." That means eaten.

Sam says, "Some acids and alkalis are corrosive or flammable and can cause chemical burns.

A danger symbol or a hazard symbol is added to products to warn that the substance is corrosive." Pause the video, complete the sentences, press play when you've completed this first part of the task.

Well done for completing the first part of the task.

Let's go through the answers.

So edible acids have a sour taste.

These acids are safe to eat and can be found in sweets and drinks.

Laboratory acids should never be consumed, so you should never eat or drink laboratory acids.

Thus anything found in the science lab at school.

Some acids and alkalis are corrosive and can cause chemical burns.

A hazard symbol is added to the products to warn that the substance is corrosive.

Well done if you got those sentences correct.

So here's part two of task A.

We're still helping the students to complete the sentences by selecting the correct word or words from the brackets.

Bases will react or not react with an acid to form a salt or an alkali.

Sam saying, "Alkalis are insoluble or soluble bases that will or will not form acidic or alkaline solutions." Pause the video while you complete the sentences and press play and we'll go through the answers together.

Well done for completing that task.

Let's go through the answers.

Bases will react with an acid to form a salt.

Sam said, "Alkalis are soluble bases," that means that they can dissolve in water, "that will form alkaline solutions." So well done if you got that correct.

Well done for working hard during the first learning cycle.

Now we're going to learn all about red and blue litmus paper.

To see if a solution is an acid or an alkali, we can use litmus paper, which is either red or blue in colour.

So here's some blue litmus paper and here's some red litmus paper.

They come in these tiny little books and you just pull a little piece out and then you can use it.

Red and blue litmus paper will change colour to show if a solution is either an acid or an alkali.

So if we have a look here, we've got some acid in this watch glass and we've dipped some red litmus paper and some blue litmus paper into it.

You can see that the red litmus paper has stayed red at the end where it's wet with the acid and the blue litmus paper has turned from blue to red.

Now, if we do the same with the red litmus paper and the blue litmus paper, this time we're putting them into an alkali and you can see that the red litmus paper has turned blue and the blue litmus paper has stayed blue.

So here's a little table that summarises it.

So in a solution of acid, red litmus paper will go from red and it will stay red.

And blue litmus paper will start off blue and turn red in an acid.

And then in an alkali, we've got red litmus paper, which will turn blue and the blue litmus paper will stay blue.

What will happen if you place blue litmus paper and red litmus paper in an acidic solution? So will it? The blue litmus paper would turn red or the blue litmus paper would stay blue? The red litmus paper would turn blue or the red litmus paper would stay red.

Pause the video while you have a think about that and then press play when you've got your answer or answers.

Well done for completing that task.

The blue litmus paper would turn red in acid and the red litmus paper would stay red in acid.

So in an acidic solution.

A piece of red litmus paper is placed in a cleaning solution.

The litmus paper turns blue.

This shows that the cleaning solution is? Is it acidic, is it neutral, or is it alkaline? Pause the video now while you have a think.

Then press play when you've got your answer.

Well done if you said because the red litmus paper turned blue, this shows that the cleaning solution is alkaline.

So well done if you got that one correct.

So here's the practical task.

You're going to be given six solutions to test from your teacher, and you're going to test them with red and blue litmus paper.

And then you're going to use your results to see if the solution is an acid or an alkali.

So here's your results table and then let's have a look at the method.

So here's your method.

You're going to collect your test tubes containing all the six household solutions.

So there's the test tubes.

You should get 'em in a test tube wrap to make it easy for you to carry them over to where you're working.

They'll have the solutions inside of them.

Then you're going to use a pipette and you're gonna place three or four drops of solution into the spotting tile well.

So there's a spotting tile well.

That's a little dimple in the spotting tile.

And here's a pipette.

The next thing you're gonna do is you're gonna place the end of a piece of red and blue litmus paper in the solution.

Then what you're going to do is you're going to observe your results and record them in your results table.

Pause the video while you carry out the practical and then press play and we'll discuss the results together.

So your results might look similar to these.

So these are the six solutions that I used, lemon juice, vinegar, cleaner, toothpaste, milk, and a fizzy drink.

And then all I did was look at the colour of the red litmus paper after the test.

So the lemon juice was red and the blue litmus paper was also red, and was it an acid or an alkali? Because the blue litmus paper turned red, we know that that is an acid.

Then we did the same with the vinegar.

So we found that the red litmus paper was red.

The blue litmus paper turned red, and therefore, it was an acid.

With the cleaner, the red litmus paper turned blue and the blue litmus paper stayed blue, and that means that that is an alkali.

With the toothpaste, it was the red litmus paper turned blue and the blue litmus paper stayed blue.

So that's an alkali.

With the milk, the red litmus paper stayed red.

The blue litmus paper turned red, and that means it's an acid.

And for the fizzy drink, the red litmus paper stayed red and the blue litmus paper turned red.

That means that it's also an acid.

So well done if you've carried out that experiment successfully.

Part two of task B.

Andeep tested some household solutions using red and blue litmus paper to see if there were acidic or alkaline.

So his A, he found out that the cleaning solution was alkaline.

Describe what he would observe.

B, some fizzy drink was tested.

Red litmus paper remained red, so it stayed red.

Describe what you would expect to see for the blue litmus paper and what conclusion Andeep could write.

Andeep said that lemons, limes and oranges are all acidic.

What I want you to do is write a method for an experiment that he could carry out to prove that he is correct.

Draw a results table for him to fill in.

So pause the video while you complete this part of task B and then press play and we'll go through the answers together.

Well done for completing that task.

Let's have a look at Andeep's results.

So he found out that a cleaning solution was alkaline and what did he see? So he should see the red litmus paper turn blue and the blue litmus paper should stay blue.

You need to have written about both the different colours of litmus paper.

Some fizzy drink was tested.

Red litmus paper remained red.

Describe what he would expect to see for the blue litmus paper and then what conclusion he could write.

So the blue litmus paper should turn red because the red litmus paper stayed red and Andeep could conclude that the fizzy drink was acidic.

Let's see how you got on with Andeep's method.

So the method should be similar to this.

Firstly, you want to squeeze and collect separately the juice from a lemon, a lime, and an orange.

Then you're going to place three to four drops of each juice in a well of a spotting tile using a pipette.

Then you're going to place the end of red and blue litmus paper into each juice.

You're going to observe, so you're going to look at and record the colour of the red and blue litmus paper.

So here's what your results table could look like.

Well done for completing that task.

Here's a summary for the acids and bases lesson.

Edible acids have a sour taste.

A base is a substance that reacts with acids to form a compound called a salt.

Alkalis are soluble bases and form alkaline solutions.

Some acids and alkalis are corrosive and can cause chemical burns.

An acid turns blue litmus paper red, an alkali turns red litmus paper blue.

Well done for working really hard this lesson.

I hope you've enjoyed carrying out that practical on acids and alkalis, and I hope you're feeling much more knowledgeable about acids, bases and alkalis.

I hope to see you in a lesson sometime soon.