Welcome to today's lesson.

Today we're going to learn about chemical reactions, and this is the lesson on neutralisation.

It's part of the unit, Acid and Bases.

Today's lesson is all about neutralisation.

You might have heard of this word before, but don't worry if you haven't because we are going to work through this step-by-step, and by the end of the lesson you should be able to describe what happens during a neutralisation reaction and write word and symbol equations to represent different neutralisation reactions.

Today's keywords are neutralisation, metal salt, aqueous solution.

You can pause the video now to read the definitions and then press play when you're ready to start the lesson.

Today's lesson consists of two learning cycles, neutralisation and neutralisation equations.

So let's get going with neutralisation.

The pH of a solution can be increased or decreased when you add an acid or base slash alkali.

If you remember, an alkali is a soluble base.

It can be observed, so you can see this by adding an indicator.

So, here's the universal indicator scale.

It goes from 1 to 14.

So at one end we've got acidic solutions on the low end of the scale, the low pHs.

And then we've got high pHs which are alkaline, so they're the blue and purple colour that that indicator would change.

And in the middle we've got neutral, which is pH 7, and it's a green colour.

So we can increase the pH by adding a base or an alkaline, and we can decrease the pH by adding an acid.

Now if we want to get something to neutral, we've got to add the correct quantities of acids and bases or alkalis.

True or false.

When acids and bases or alkalis are mixed in the correct quantities, a neutral solution is made.

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

Well done if you said that that statement was true.

When acids and bases or alkalis are mixed in the correct quantities, a neutral solution is made.

Now I want you to justify your answer.

So, you've got two choices here.

Acids and bases are alkalis in correct quantities will react to form a neutral pH 7 solution.

Or acids and bases are alkalis in correct quantities will react to form a neutral pH 1 solution.

Pause the video while you decide which is the correct justification and then press play, and I'll tell you if you're right or not.

Well done if you said acids and bases or alkalis in correct quantities will react from a neutral pH 7 solution.

Remember, if you've got universal indicator paper or universal indicator solution, it will turn green.

So well done if you got that one correct.

Here I've got three test tubes that each contain a solution.

We want to know which test tube contains a neutral solution.

In the top of these is a piece of universal indicator, which is change colour.

So is it a, green, b, blue or c, red.

Pause the video while you decide, then come back and press play, and I'll tell you if you're right.

Well done if you said a, green.

The test tube that contains a neutral solution must be the one that turns universal indicator paper green.

Well done if you got that correct.

So to neutralise an acid, an alkali can be added because adding an alkali increases the pH.

So here we've got some acid with universal indicator solution added.

You can see it's a red colour.

If we add alkali drop by drop, we should eventually achieve neutralisation and that will give us a neutral solution and that will then change to a green colour on the pH scale and the pH of that solution has increased.

Now we're going to look at how to neutralise an alkali.

So if you want to neutralise an alkali, an acid can be added.

So here's an acid here being added drop by drop to an alkaline solution with universal indicator added to it.

So, it starts off blue.

You're going to add the acid drop by drop.

We're going to achieve neutralisation and that neutral solution will be a green colour.

For that to happen, the pH of the solution has decreased.

Here's a solution with some universal indicator in.

It's changed to an orange colour.

So what needs to be added to this solution to neutralise it? Is it acid, is it alkali or is it a neutral solution? Pause the video while you decide and then press play, and I'll tell you if you're right or not.

Well done if you said you need to add an alkali to this solution, 'cause this solution is orange colour, which shows that it is an acid.

So well done if you got that one correct.

Let's have another check for understanding now.

What will happen to the pH of this solution when it is neutralised? So, it's a purple colour.

Will it increase to pH 7, decrease to pH 7 or increase to pH 12? Pause the video now while you decide, then press play, and I'll tell you if you're right.

So well done if you said it would decrease to pH 7.

The purple colour shows that it's an alkaline solution and you need to get it to pH 7, so that pH must decrease by adding an acid to it.

So well done if you got that one correct.

Here's part one of task A1 neutralisation.

You'll be given an acid and we'll use an alkali to neutralise it.

So here's the acid in the test tube and the universal indicator solution is probably going to come to you in a little drop of bottle like this.

You're going to add two to three drops of universal indicator solution to the acid.

Then step two, you're going to add one drop of alkali to the acid using this pipette.

Then step three, you're going to mix the solution by shaking the test tube from side to side.

So you're just going to sway the test tube from side to side.

And this will allow it to mix up without it splashing out.

Step four, you're going to repeat steps two and three until you've reached a pH 7.

And this should be a neutral green solution.

So you're going to add one drop of alkali to the acid, give it a mix, take a look at the colour and you're going to continue until you've reached this green colour.

Now the problem is sometimes you might add one or two drops of alkali too much.

If that's the case, you are going to then add drops of acid to your solution if your solution becomes too alkaline and becomes purple or blue.

So what you're gonna do then is you're going to use acid to then bring the pH down to a neutral green pH.

So good luck with your practical task, pause the video while you carry it out and then press play.

So congratulations if you manage to achieve a green neutral solution, you've made a solution of a soluble salt and water.

Well done.

Here's part two of task A.

What would you add to the solution to neutralise it? And you're going to choose either acid or alkaline.

So, here's the first one.

A solution that is red in colour when universal indicator is added, what are you going to add to that solution to make it neutral? Would you add acid or would you add alkaline? B is a solution that turns universal indicator paper blue.

Now I've got three pictures for you.

So C is universal indicator paper is turned yellow when placed in that solution.

D, universal indicator paper is turned red when you've placed it in the solution.

E, universal indicator paper has turned purple when you've placed it in the solution.

Then we've got blue litmus paper that has turned red.

And then a solution where red litmus paper turns blue when added to it.

So pause the video while you choose either acid or alkaline, then press play, and we'll go through the answers together.

Let's have a look at the answers.

So a solution that is red in colour when universal indicator is added, we must be adding an alkali to that because a solution that is red when universal indicator is added must be an acid.

So we need to add alkali to increase the pH to neutral.

A solution that turns universal indicator paper blue.

We're going to be adding an acid to that to reduce the pH until it's pH 7 showing that green colour, so that's neutral.

Then we've got these three pitches here.

So yellow, it's we're going to be adding an alkali to that because yellow indicates acid, so we need to increase the pH by adding an alkali.

Red, again, it's an acidic solution.

So we're going to add alkali to increase the pH to pH 7 and then we're going to look at the purple one.

So we need to do the opposite here 'cause that's an alkali already.

So we're going to need to add acid to reduce the pH to pH 7.

Blue litmus paper turning red indicates an acid, so that must be an acidic solution.

So we must have to add alkali to increase the pH to neutral.

And finally, a solution where red litmus paper turns blue.

So that's shown that it's an alkaline solution.

What we're going to do is we're going to add acid to decrease the pH of that solution to pH 7, which is neutral.

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

We've completed our first learning cycle of neutralisation.

Now we're going to look at neutralisation equations.

In chemical equations you can identify the state of matter of each substance.

And you can use these when writing a word or symbol equation.

Just gives a little bit more information about what's going on in your reaction.

So here's the states of matter.

Solid, lowercase s in bracket.

Liquid, lower case l in bracket.

Gas, lower case g in bracket.

And in solution, which we say aqueous shortened for aq.

And that's lowercase and that's also in brackets.

So there's some rules about how to write the states of matter.

So they must be written in lowercase, must be written in subscript.

And all that means it is slightly smaller and it's below the line of where the word is written or the symbol is written.

And it must be included in brackets.

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

And then you can see that that g is in brackets, lowercase and it's also in subscript, so smaller and below the line.

Or we could write it using the symbol CO2.

And you can see that that g is in brackets, it's in lowercase and it's in subscript.

So it's the same height and size as the number two there.

Got another example for you here.

This is solid sodium hydroxide.

So this is where it starts to become really useful because sodium hydroxide comes in different forms. So solid sodium hydroxide would be written sodium hydroxide and then in bracket lowercase s and in subscript or also you could have NaOH and it's in bracket and it's a lowercase s.

We could also have sodium hydroxide solution.

So, if we were having sodium hydroxide in our reaction.

We might be interested in are we going to use sodium hydroxide solution or are we going to use solid sodium hydroxide? And in this case the sodium hydroxide would be written in words and then aq, short for aqueous meaning water, so it's in solution.

And that would be in brackets and it would be subscript.

And then we've also got NaOH, which is a symbol for the compound sodium hydroxide.

And we would write this lowercase in brackets, in subscript.

Here's a quick check for understanding.

What is the correct way to use a state symbol for copper sulphate solution? I want you to select the correct answer or answers.

So have a really good look at those options.

Pause the video once you do that and then press play, and I'll go through the answer or answers.

So, well done if you said it's b.

it does need to be lowercase and in bracket and in subscript.

So, well done if you got that correct.

True or false.

The correct way to write the state symbol for solid sodium chloride, NaCl is NaCl, brackets, aq, close brackets.

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

So well done if you said that that was false.

And let's have a justification for that now please.

So the state symbol for solid is in brackets s.

It should be written in lowercase, in brackets and in subscript.

Or is it the state symbol for solid is S.

And that's a capital S.

It should be written in uppercase in brackets and in superscript.

So pause the video while you decide which one's correct and then press play, and I'll tell you if you're right.

So well done If you said that that was a.

The state symbol for a solid is it must be lowercase s and it should be in brackets and it also should be in subscript.

So, well done if you got that correct.

When a neutralisation reaction happens, the general equation is acid plus based makes metal salt and water.

So let's have a look at a specific example.

So the neutralisation of hydrochloric acid with sodium hydroxide solution is, hydrochloric acid plus sodium hydroxide makes sodium chloride plus water.

So we've got HCL plus NaOH makes sodium chloride plus water.

Now the problem with this is that these equations tell you a lot but it doesn't tell you all about the states.

So we need to put the state symbols in here.

So hydrochloric acid, that is always a solution.

And then it tells you there that the sodium hydroxide is a solution.

And because we make water, the sodium chloride that's made must also be in solution.

And the water, well the water in these reactions at room temperature is always liquid.

So, we put our state symbols in there.

Hydrochloric acid (aq) showing that it's a solution.

Sodium hydroxide (aq) meaning that that's a solution.

And sodium chloride (aq) because that's dissolved in the water and the water is produced from the reaction and that is a liquid because you cannot have water dissolved in water.

So we can put them in the word equation.

There are the state symbols in the word equation.

We could also put them in the symbol equation here.

So, I've got a quick check now for understanding.

What is a general equation for the reaction between an acid and a base to produce a metal salt and water? Is it acid plus base makes solution plus water, acid plus base makes metal salt plus hydrogen, acid plus base makes metal salt plus water.

Pause the video while you decide which one it is, and then press play, and I'll tell you if you're right or not.

So well done If you said it's c, acid plus base makes metal salt plus water.

Well done if you got that one correct.

Common metal oxides and hydroxides are bases.

And sodium hydroxide, calcium oxide and copper oxide are common bases and these will all neutralise in acid.

So let's have a look at some pictures of them.

Here's sodium hydroxide, here's calcium oxide, and here's copper oxide.

And all of these are bases, so you can add these to acids to neutralise them.

Which substance could be a base? Carbon dioxide, magnesium oxide, copper sulphate.

Pause the video, choose your answer and then press play, and we'll go through the answer together.

Well done if you said magnesium oxide.

That's the only metal oxide listed there.

So magnesium's the metal, so that makes magnesium oxide a metal oxide, that can be a base.

Well done if you got that one correct.

In a neutralisation reaction, the salt formed is named after the metal, which is from the base and an acid used.

So, let's have a look.

So we've got hydrochloric acid makes chlorides, sulfuric acid makes sulphates, nitric acid makes nitrates.

So we can change the salt produced by changing the acid.

So let's have a look at an example here.

So we've got hydrochloric acid plus sodium hydroxide makes sodium chloride plus water.

So you can see here the first part of the metal salt name is always the metal.

So, that's sodium.

So, that's from the base.

And the hydrochloric acid bit, that gives the ending of the metal salt, so that means that it's a hydrochloric acid makes chlorides.

A quick check for understanding now.

Which metal salt can be formed by the neutralisation reaction between magnesium oxide and sulfuric acid? Pause the video while you decide and then press play when you've got the answer.

So well done if you said magnesium sulphate.

Because we've used magnesium oxide, the salt made must start with the word, magnesium.

And the last bit of the salt, the ending, we've got sulfuric acid.

So, sulfuric acid makes sulphate.

So we put those two bits of knowledge together and we get magnesium sulphate.

Well done if you've got that one correct.

So now we've going to write state symbols for neutralisation reaction word equation.

So here we've got acid plus base makes metal salt and water.

That's our general equation.

So acids are always a solution in the school laboratory, so we would write aq for that.

Bases, now these could be a solid or a solution.

More information is needed and that would usually be given in the question if you were asked a question about this.

So that could be a solution or it could be a solid.

So I've just put aq showing that this one is a solution and we've got a metal salt, so that could be a solid or a solution.

More information is needed about metal salts.

So some of the metal salts are not soluble in the water, but this one must be because I've written aq showing that that salt has been dissolved in the water that's produced in the equation.

So water is always a liquid at room temperature, so it is always a lowercase l for water 'cause you cannot have water dissolved in water.

What I'd like you to do now is select which option completes the sentence.

Acids used in the school laboratory are? Are they always in solution and have the state symbol (aq), always in the solution and have the state symbol (L), always a liquid and have the state symbol (L), always a solid and have the state symbol (s).

So pause the video once you decide and then press play, and I'll tell you the answer.

Well done if you said the acids used in the school laboratory are always in solution and have the state symbol (aq).

Well done if you got that one correct.

So in these neutralisation reactions, the metal salt formed is always named after the metal from the base and the acid used.

So, let's have a look.

So, we've got the name of the acid.

So we've got hydrochloric acid, sulfuric acid, nitric acid and got the chemical formulas for them and the ending of the metal salts and also the chemical formula for the metal salt ending.

So hydrochloric acid, the formula for the acid is HCl.

The name of the metal salt ending would be chloride.

And we would write that Cl.

We've got sulfuric acid.

The chemical formula for this is H2SO4.

And that would make metal salts ending in sulphate.

And the chemical formula for the metal salt ending, so sulphates are always SO4.

Then we've got nitric acid there.

Chemical formula of the acid is HNO3.

And we make nitrates.

So the metal salts would be a nitrate.

And the chemical formula for the metal salt ending would be NO3.

Let's have a look at an example.

So we've got hydrochloric acid plus sodium hydroxide makes sodium chloride plus water.

So we've got HCL plus NaOH makes NaCl plus H2O.

We can see there that the sodium, so the symbol for sodium is Na and we can see that that forms a start of the formula for sodium chloride.

And then the ending of the acid, so hydrochloric acid, that becomes the ending for the metal salt.

So, that's sodium chloride.

So I've got a quick check here for you.

What is a formula for the metal salt formed from the neutralisation reaction between zinc oxide? That's the ZnO and sulfuric acid, H2SO4.

Is it MgSO4, ZnSO4, ZnNO3? Pause the video now while you decide, press play, and I'll go through the answers.

Well done if you said that that was ZnSO4.

Well done if you got that one correct.

So what we're going to do now is I'm going to go through how to write the state symbols for the symbol equation that's been described in words and then you are going to have a go.

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

So here's the equation here.

And now what we're going to do is going to write the state symbols for this symbol equation.

So the first one we're going to do is the first bit there, H2SO4, that is sulfuric acid.

And we know that all of the acids in the lab are in solution.

So we're going to write aq, must be in brackets, must be subscript and it must be lowercase.

Next we're going to have a look at the words there.

So it says sulfuric acid and potassium hydroxide solution.

So because it says solution, again, we're going to write aq in brackets there and it says it produces a soluble potassium sulphate.

So because it says the word, soluble, that means it can dissolve in water.

So that means it's going to make a solution.

So, that's aq.

And water which is always liquid.

So that's lowercase l in bracket and subscript.

Now you are gonna have a go.

So what I want you to do is write the state symbols for the symbol equation that has been described in words.

So, here's the words.

A neutralisation reaction takes place between hydrochloric acid and silver hydroxide solution producing insoluble silver chloride and water.

Here's your equation.

What I want you to do now is pause the video, then you're going to add in those state symbols written correctly and then press play, and we'll go through the answers together.

Well done for completing that.

Let's have a look.

So the first one is HCL, so that's hydrochloric acid.

And we've said that that must be in solution because they're all solutions.

So, that's aq.

Then we're going to have a look at the next bit.

It says silver hydroxide solution.

So because it says solution, that means it's dissolved in water.

So, that's also aq.

Then we're gonna have a look at silver chloride here and it says this time it says it produces insoluble silver chloride.

That means it won't dissolve in water.

So that means it must be a solid.

So we're going to write an S, lowercase S in brackets.

And finally and water.

So water is always a liquid at room temperature.

So we're going to write an l in bracket, lowercase l.

So well done if you've managed to get that correct.

What I want you to do now is tell me what is the formula for the metal salt formed from potassium hydroxide.

So that's KOH.

And nitric acid.

So, that's HNO3.

Is it MgCl, is it PNO3, is it KNO3? Pause the video whilst you decide, then press play, and I'll tell you if you're right.

So well done if you said c, KNO3.

Remember the metal salt gets its name firstly from the metal, so potassium hydroxide would make potassium.

That's the metal.

So that symbol for that is a K.

And nitric acid, the metal salt ending comes from the ending of the acid, so that's NO3.

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

What I want you to do now is tell me the state symbol for water at room temperature.

So take a look at your options there, select one of them.

Whilst you're doing that, pause the video and have a little think, then press play and I'll tell you if you're right or not.

Well done if you said it was c, H2O.

And then a little lowercase l in bracket, subscript.

Well done if you've got that one correct.

What I want you to do for this task is match up the state with a substance correctly represented in that state.

So here we've got four different states.

We've got aqueous, gas, liquid and solid.

And you're going to find an example.

So I'm going to give you 12 different examples and you've just got to match one of those examples up to the state.

So here's three of them, three more, three more and three more.

So you've got a total of 12 to choose from and I want you to just match them up.

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

Well done for completing that task.

Let's see if you managed to find an example of aqueous.

So, there we go.

You can see aq in brackets, lowercase and subscript.

Gas, there's hydrogen gas there.

Again, lowercase g, in bracket and subscript.

Liquid, so that's water there we've got.

It's a lowercase l, in brackets in subscript.

And finally solid.

Where's our solid example? There it is, it's calcium carbonate, it is in lowercase and it's in subscript and it's in bracket.

So, well done if you managed to find those different state examples.

What I'd like you to do is correct the statements of these pupils.

So, here's Aisha.

In a combustion or neutralisation reaction, the acid or salt formed is named after the metal in the base and the acid used.

Jacob's saying, when using hydrochloric acid, metal salts called metal sulphates are formed.

Lucas is saying zinc oxide reacts with nitric acid to form a salt called magnesium nitrate.

So I'd like you to correct all of these statements to make them correct statements or pause a video whilst you do that, press play, and we'll go through the answers together.

Well done for working hard and completing that.

In a neutralisation reaction that salt formed is named after the metal in the base and acid used.

Here we've got when using hydrochloric acid, metal salts called metal chlorides are formed.

But you could have also written it the other way around when using sulfuric acid, metal salts called metal sulphates are formed.

Then we've got Lucas, zinc oxide reacts with nitric acid to form a salt called zinc nitrate.

And also acceptable, magnesium oxide reacts with nitric acid to form a salt called magnesium nitrate.

So well done if you've got those correct, you're doing really well.

What I'd like you to do now for part three is name the metal salt formed where metal hydroxides and metal oxides react with acids.

So I've got a table of information to help you with that.

Some magnesium oxide and nitric acid, potassium hydroxide and sulfuric acid, zinc oxide and hydrochloric acid, lead hydroxide and hydrochloric acid, lithium hydroxide and sulfuric acid.

Pause the video while you do this, then press play, and I'll tell you the answers.

Well done for completing that task.

Let's see how you got on.

So we were naming the metal salts formed with metal hydroxide and metal oxide react with acids.

So magnesium oxide and nitric acid must make magnesium nitrate, 'cause the first part of the metal salt name is from the metal oxide and the second part is from the acid.

So magnesium nitrates formed for that first one.

Potassium hydroxide and sulfuric acid makes potassium sulphate, zinc oxide and hydrochloric acid makes zinc chloride, lead hydroxide and hydrochloric acid makes lead chloride, lithium hydroxide and sulfuric acid makes lithium sulphate.

Well done if you've got all of those correct.

For this task, you'll need the information from the tables to help you.

You can find this in the additional materials.

What I want you to do is complete the equations including missing state symbols using the correct chemical symbols.

So, here's the first one.

You can see it's missing something.

I want you to write what's missing and also the state symbol for that.

Again here, what's missing on the state symbol? We've got two things missing here and I want those state symbols.

Again for this.

And this one.

And finally this one.

So pause the video whilst you complete this, then press play, and we'll go through the answers together.

Well done for completing that task.

I hope you got on okay with it.

So if you remember from the general equation, acid plus base makes salt and water.

So here we've got the acid, which is hydrochloric acid, the base, which is potassium hydroxide and that's going to make potassium chloride and water.

So water is always made in these equations.

And because they take place at room temperature, it's always a liquid.

Then what you've got to do for this one is figure out which acid it is.

So now I'm looking at the salt produced, so that's calcium chloride.

So that must mean that we must have hydrochloric acid there.

So that's HCL and that is aqueous.

It's a solution in the lab.

Next one, what kind of acid makes zinc sulphate? So we must have had sulfuric acid there.

And remember we always make water.

And water is always in the liquid state and the acids are always aqueous dissolved in water.

Next one here, we've got what base is going to react to make calcium chloride.

So, let's have a look.

So we've got calcium oxide here, makes calcium chloride plus water.

Then this next one we've got sulfuric acid 'cause we're going to make a sulphate, salt and we always make water, which is always in the liquid state.

And then finally we've got nitric acid plus zinc oxide is going to make zinc nitrate plus water.

So well done if you've managed to get all those missing symbols correct.

Here's a summary of today's lesson.

In chemical equations, (s), (l), (g) and (aq) identify the state of each substance as solid, liquid, gas, or in solution.

Neutralisation reaction general equation is base plus acid makes metal salt plus water.

Sodium hydroxide has a formula, NaOH (aq) and hydrochloric acid has a formula HCl (aq).

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

Common bases include metal oxides and hydroxides, for example, CuO, which is copper oxide, and KOH, which is potassium hydroxide.

Well done for working really hard this lesson.

I hope you enjoyed that little neutralisation practical and also now feel much more confident in writing both word and symbol equations, including states for acid plus base makes metal salt and water equations.

I hope to see you back sometime soon.