Hello.

Welcome to our lesson today.

This is on acid based reactions, so we're gonna to look at what an acid is, what a base is, what an alkali is, and what a neutralisation reaction is.

This is part of the "Making Salts" unit.

My name is Mrs. Clegg.

Let's start the lesson.

Here's the outcome for today's lesson.

By the end of it, you should feel more confident at being able to identify substances which are classified as bases.

You'll understand how to predict the names and the states of products from neutralisation reactions, and we'll also compare the properties of metal and non-metal oxides.

So let's begin.

Here are the key words for today's lesson.

Here are those words written into a sentence.

You might like to pause the video and make some notes to help yourself throughout the lesson.

Today's lesson is split into three parts.

Types of bases, neutralisation reactions, and then we're going to compare metal and non-metal oxides.

Let's get started with the first part.

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

Alkalis are soluble bases, and they form alkaline solutions.

So an example that you've probably come across is sodium hydroxide.

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

Copper oxide, on the other hand, is a base, but it's not an alkali, because it's not soluble in water.

There are three main types of base.

Hydroxides containing the hydroxide ions, OH-.

For example, sodium hydroxide and magnesium hydroxide.

We've got oxides containing the oxide ion, O2-, for example, potassium oxide and copper oxide.

And then we've got carbonates, containing the carbonate ion CO3 2-, for example, calcium carbonate and zinc carbonate.

A further base that we should consider is ammonia, and ammonia produces hydroxide ions when it dissolves in water.

And here's the equation.

Let's do a quick check.

Which of these are bases? Well done if you said iron hydroxide, and even better if you noticed aluminium oxide and lithium carbonate.

Well done.

Now all bases react with acids to form salts, but most bases are actually insoluble in water.

So the circle, the purple circle, represents the insoluble bases, which is most of them, as you can see.

And then the green circle in the middle there represents the soluble bases, which we call alkalis.

So you can see alkalis are a much smaller subset of bases.

Let's have a look at task A.

So I'd like you to look at the table.

You've got the base formulae, and I'd like you to write the name of those bases in words.

It might be useful to have a periodic table to help you.

Pause the video and come back when you're ready.

How did you do? Let's have a look.

So the first one is calcium oxide, potassium hydroxide, magnesium carbonate, lithium oxide, beryllium hydroxide, and ammonia.

Well done.

Question two.

So we've got Laura and Jacob discussing bases.

They've made several statements, and I'd like you to decide which statement is correct, and then amend any of their incorrect ideas.

So here's their statements.

Pause the video and come back when you're ready.

Okay, let's have a look.

So the first statement by Laura was incorrect.

Let's change that to be correct.

So most bases are insoluble and they release hydroxide ions.

And then her second statement, again, that was incorrect.

How do we correct it? We add carbonates there.

So we know three main types of base, hydroxide, oxides, and carbonates.

Let's have a look at Jacob.

So Jacob's first statement is incorrect, and we change that to say sodium chloride is a type of salt.

And then Jacob's second statement is correct.

Well done if you've got all of those.

We're going to move on to the second part of our lesson now, neutralisation reactions.

So in chemical equations, you should be able to identify the state of matter of each substance, solid, liquid, gas, or aqueous.

And you should be able to use it when writing a symbol equation.

So let's just familiarise ourselves with the states of matter symbols.

So little s there, in brackets, l, g, and aq.

So those are the states of matter we should be using.

Let's just have a refresh about how to write them.

They must be in lowercase, subscript, and in brackets.

So for example, carbon dioxide gas would be written like this.

And solid sodium hydroxide would be written like this.

And a sodium hydroxide solution would be written like this.

And it's aq because it's in solution, it's aqueous.

Let's have a quick check to see how comfortable we are with that then.

So what is the correct way to use a state symbol for zinc sulphate solution? Select the correct answer or answers.

Have a look.

Well done if you said B.

It's not A, because the aq is in capitals there.

It's not C because the aq is not subscript.

And it's not D because the aq is not in brackets.

Let's have another question.

True or false? The correct way to write the state symbol for solid copper oxide is.

There we go.

Is that true or false? Well done if you said false, and now let's justify the answer.

Well done if you said A.

Lowercase, in brackets, and subscript.

Fantastic.

Let's have a look at neutralisation reactions now.

And they are when an acid reacts with a base.

There are lots and lots and lots of examples of this reaction happening in every day.

So for example, if you've got a stomach upset, you might be taking indigestion tablets to neutralise stomach acid.

If you get a bee sting, then you might use bicarbonate of soda to neutralise the bee sting, 'cause the bee sting is acidic.

And we can write a neutralisation reaction as a general equation.

So acid plus base combine to form salt plus water.

So let's look at a specific example.

The neutralisation of hydrochloric acid with sodium hydroxide solution would be hydrochloric acid plus sodium hydroxide combined together to form sodium chloride and water, and there's the symbol equation as well.

And then here are the state symbols.

So let's have a quick check.

What is the general equation for the reaction between an acid and a base? Which of those is correct? Give you a moment.

Well done if you said C.

Fantastic.

When alkalis react with acids, they either release or produce hydroxide ions and form salts.

Neutralisation occurs when equal concentrations of hydroxide ions and hydrogen ions released by the acid react to form water.

So there must be equal concentrations for neutralisation to occur.

So here we've got hydrogen ions and hydroxide ions combining in equal quantities to form water.

And this equation is known as the ionic equation of neutralisation.

Let's have a quick check.

The state symbol for water at room temperature is, which one of those would be correct? Well done if you said C.

It's the only one that has got liquid for water.

Water is not a solid at room temperature, so it can't be A.

Water's not a gas at room temperature, so it can't be G.

And water cannot be aqueous, because water is water, so it can't be dissolved in water.

In a neutralisation reaction, the salt formed is named after the metal from the base and from the acid that's used.

So if we look at this table, we've got the type of acid, and then we've got the metal salt ending.

So hydrochloric acid has chloride as the metal salt ending.

Sulfuric, sulphate, nitric, nitrate.

Let's have a look at specific example.

So hydrochloric acid and sodium hydroxide form sodium chloride and water.

So sodium from the base there can be seen in sodium chloride.

And the chloride from the hydrochloric acid forms the salt.

Let's have a look at those again then.

Just again.

So the salt formed, remember, is named after the metal from the base and the acid used.

So if we find the base, that's sodium hydroxide, there's the metal.

And so we see the sodium in the salt, and then the acid is hydrochloric, and the name of the ending therefore is going to be chloride.

So we get sodium chloride and water.

So let's have a quick check.

Which salt can be formed by the neutralisation reaction between iron oxide and sulfuric acid? Well done if you said iron sulphate.

So the iron is coming from the base, iron oxide, and the sulphate is coming from the acid, sulfuric acid.

Well done.

Neutralisation reactions can be written as both word equations and symbol equations, and if we're using a symbol equation, we should be using the state symbols, solid, liquid, gas, or aqueous.

Here we can see in this table, we've got the name of the acid, the chemical formula for the acids, which you might need to take note of, the name of the non-metal ion that's released from the acid, and the chemical formula of that non-metal ion.

So if we look at this equation again, hydrochloric acid and sodium hydroxide produce sodium chloride and water.

And we've got hydrochloric acid, which is aqueous.

Sodium hydroxide, which is aqueous.

Produce aqueous sodium chloride, and water.

Now let's just refresh ourselves how we name sodium chloride.

So we've got the sodium metal from the base there, and the chloride is coming from the acid, hydrochloric acid.

Let's have a quick check.

What is the formula for the salt formed from the neutralisation reaction between zinc oxide and sulfuric acid? Well done if you said B.

So it can't be A, because there is no magnesium involved in the reaction at all.

And it's not going to be C, because the acid that was used was sulfuric acid, not nitric acid.

Well done.

Let's have a look at an example together.

So write the state symbols for the symbol equation that has been described in words.

A neutralisation reaction takes place between sulfuric acid and potassium hydroxide solution, producing soluble potassium sulphate and water.

And here's the equation.

So what we've got to do is add in the state symbols.

So we know that sulfuric acid is going to be aqueous.

Potassium hydroxide, if we look at the statement that we're given, potassium hydroxide solution, and therefore it's going to be aqueous there for potassium hydroxide in the equation.

And then if we look at the next part of the sentence, it says producing soluble potassium sulphate.

So that's also going to be aqueous.

And then water is a liquid.

So let's just have a look at another example there, and I'm gonna ask you to have a go.

So here's the word description of what's going on.

Could you write the state symbols for this equation? Pause the video and come back when you're ready.

Okay, let's see how you've done.

Hydrochloric acid we know is aqueous.

In the description, it says silver hydroxide solution, therefore it's aqueous.

And producing insoluble silver chloride.

So we know that's a solid.

And of course, water is a liquid.

How did you do? Let's try another question.

So what's the formula for the salt formed from potassium hydroxide and nitric acid? Well done if you said C, potassium nitrate.

It can only really be C, because if we look at A, there's no magnesium and no chloride in the description.

And similarly, P is the symbol for phosphorus.

Neutralisation reactions involving ammonia actually only produce one product.

So acid and ammonia combine to form an ammonium salt.

So that's the general equation for ammonia and acids.

So the neutralisation of hydrochloric acid with ammonia would be hydrochloric acid plus ammonia, and combines to give ammonium chloride.

And here's the equation.

But in reality, ammonia reacts with water when it's dissolved to make ammonium hydroxide, which acts as an alkali.

So really, the general equation is more like this.

Acid plus ammonium hydroxide produces ammonium salt plus water.

So if we looked at hydrochloric acid, the reaction would be hydrochloric acid plus ammonium hydroxide combine to form ammonium chloride plus water.

And here's the equation, and don't forget the water.

So what would be produced if ammonia was reacting with sulfuric acid? Well done if you said ammonium sulphate.

Good.

So let's have a go at task B.

What I'd like you to do is complete the following word equations.

Pause the video and join us when you've completed them.

Okay, let's have a look at the answers.

So acid plus hydroxide base would produce salt plus water.

Acid in an oxide base, similarly, salt plus water.

And here we've got some specific examples now.

Sulfuric acid plus copper hydroxide would produce copper sulphate and water.

Nitric acid plus zinc oxide gives us zinc nitrate and water.

Well done if you've got all those correct.

So let's have a look at question two.

So now I'd like you to write balanced symbol equations for the following reactions, and don't forget the state symbols.

There is a table there with the formula of the acids and some of the alkalis and bases there.

So use those to help you.

Pause the video, and come back when you're ready.

And here are the answers.

You might like to pause the video to just mark yours and check they're correct.

Let's move on to the last part of our lesson now, metals and non-metal oxides.

So metal oxides are ionic compounds that consist of metal ions bonded to oxide ions.

And there are many, many metal oxides that exist.

For example, calcium oxide, chromium oxide, iron oxide, mercury oxide.

Let's have a quick check.

So select all the correct statements here.

There might be more than one.

Okay, well done if you said A and D.

Well done.

Let's have a closer look at metal oxides now.

So remember, metal oxides are bases, and the small amount of them which are soluble will turn universal indicator a blue colour when it's dissolved in water.

So we're going to watch a small video now.

This involves a bit of magnesium metal being placed in the bunsen burner.

The magnesium reacts with oxygen to form magnesium oxide.

And then we're gonna see what happens when the magnesium oxide is dissolved in water and tested with universal indicator.

So the bunsen is being put to the roaring flame.

A strip of magnesium metal is being heated strongly.

We see a bright white light.

Magnesium is reacting with oxygen, to form magnesium oxide.

So we place magnesium oxide on the watch glass, turn the bunsen to a safety flame.

Here we're adding distilled water to both watch glasses.

And then we're going to test using universal indicator solution.

The magnesium oxide dissolves in the water, and when we test it with universal indicator, we can see that an alkaline solution is formed.

Universal indicator turns blue.

So just to recap then, metal oxides are bases, and those which are soluble will turn universal indicator a blue colour and dissolved in water.

We formed magnesium oxide, and the magnesium oxide was dissolved in water, tested with a universal indicator, and we saw an alkaline solution being formed.

So let's do a quick check.

Most metal oxides are soluble in water.

Is that true or false? Well done if you said false.

Now can you justify your answer? Well done.

Most metal oxides are insoluble in water.

There's only a few which are.

Now remember that metal oxides are bases, and so they can neutralise acids.

So the general equation is acid plus metal oxide combine to form salt and water.

And let's look at a specific example.

So hydrochloric acid plus copper oxide produces copper chloride and water.

And here's the symbol equation with the state symbols.

Let's look at non-metals now.

So a non-metal oxide consists of non-metal atoms bonded to oxygen atoms. For example, carbon dioxide.

We use carbon dioxide in fire extinguishers.

And organisms in lakes can be affected by acid rain, which is caused by pollution from a non-metal oxide, sulphur dioxide.

Let's have a look at a quick check.

So a non-metal oxide is, which of those do you think is correct? Well done if you said B, non-metal atoms bonded to oxygen atoms. Nonmetal oxides are mostly soluble in water, and they make acidic solutions.

There is one exception which is silicon dioxide.

So if we put non-metal oxide and water in a test tube, and we tested it with universal indicator paper, it would turn red, showing that it was acidic.

Carbon dioxide, for example, dissolves in water to form carbonic acid.

And there's the equation.

And we've also got sulphur trioxide, which dissolves in water to form sulfuric acid.

Let's have a quick check.

Which of these could contain nitrogen dioxide in water? Well done if you said A, because the universal indicator paper has gone red, indicating that it's acidic.

Now, rain water is usually acidic, and that's due to carbon dioxide from the atmosphere dissolving in it.

When rain is more acidic than normal, we call it acid rain.

And acid rain has a pH equal to or lower than 5.

6.

And here, non-metal oxide pollutants, such as sulphur dioxide and nitrogen oxides have also dissolved in rain.

And acid rain and rainwater will both react with carbonates, causing chemical weathering, and you can see the gargoyle there, which was probably made from limestone, which is calcium carbonate, has lost a lot of its features because it's been weathered by acid rain.

Let's have a look at task C.

So what I'd like you to do is correct the following table to sort the metal and non-metal oxides out.

Use your periodic table to help you with some unfamiliar names there.

So sort these out into the right column.

Pause the video and come back when you're ready.

So let's have a look.

How did you do? You might need to pause the video to check.

Let's have a look at question two.

Explain why acid rain causes chemical weathering on building and statues.

I want you to make sure your answer contains the following.

It covers why acid rain is acidic, and what happens when acid rain falls on buildings or statues.

Pause the video and come back when you're ready.

Okay, let's have a look.

So why acid rain is acidic.

You should have included something like this, that non-metal oxide gases in the atmosphere dissolve in rainwater, as they're soluble in water, and that makes an acidic solution.

And when acid rain falls on building or statues, it can cause the materials to deteriorate.

This can result in the weakening of the structures, loss of detail in the statues as we saw on the previous slide, and the wearing away of the material.

So you won't have written it exactly the same, but hopefully you've got those components.

So we've come to the end of the lesson now.

So let's have a look at our summary.

So we've learned today that a base is a substance that neutralises an acid to make salt and water only.

This is called a neutralisation reaction.

Hydroxides are generally soluble bases.

They contain OH- ions.

Metal oxides are bases that are generally insoluble in water.

There are very few of them that do dissolve.

But if they do dissolve, they'll form an alkaline solution.

Non-metal oxides are soluble, and they form acidic solutions in water.

So well done for sticking with us.

I hope that you feel a lot more confident now about being able to identify substances which are classified as bases.

You know what a base is, and what an alkali is.

You'll understand how to predict the names and the states of the products that are produced in neutralisation reactions, and also that you can compare the differences between metal and non-metal oxides.

Well done, and I look forward to working with you next time.