Lesson video

Hello, everyone, how are you today?

I hope you're feeling really good.

My name is Ms. Afzal, and I'll be your teacher for this lesson.

I'm feeling very pleased about that because we're looking at quite an interesting topic today.

It's catalysts.

Have you heard of catalysts, do you know what they are, or are they entirely new to you?

Don't worry, whatever is the case, we are gonna be getting right into finding out all about catalysts today.

Our lesson is called "Catalysts," and it comes from the unit of work "Materials.

" So if you're ready to dive into catalysts to begin our exploration of them, if you have energy, focus and enthusiasm, we'll begin our lesson now.

The outcome for today's lesson is, "I can describe how catalysts, including enzymes, speed up chemical reactions.

" I hope that sounds interesting to you.

We have some keywords in our lesson.

I'd like us to go through them one at a time saying them out loud.

Catalyst, enzyme, chemical reaction.

Good to hear those keywords.

Let's find out what they mean.

Catalyst, this is a chemical that speeds up the rate of a reaction without itself being used up.

Enzyme, a biological catalyst that speeds up reactions in living things.

And chemical reaction, when atoms are rearranged to make new products and changes can be observed, e.

g.

bubbles of gas forming.

So these are our keywords, catalyst, enzyme and chemical reaction.

Pause here and share with someone, had you heard of any of these keywords before?

Did you already know their meanings?

Thanks for sharing your prior knowledge of these keywords.

Let's look out and listen out for them.

Let's think carefully about them.

They'll be coming up in our lesson today.

Today's lesson is called catalysts, and it has two learning cycles.

First of all, catalysts, and next, enzymes.

Let's begin by exploring catalysts.

A catalyst is a chemical that speeds up the rate of a chemical reaction without itself being used up.

In a chemical reaction, atoms are rearranged to make new products, and changes can be observed, usually bubbles of gas forming.

The symbol equation for a reaction shows how the atoms rearrange, hydrogen peroxide reacts to form water and oxygen.

So we could say 2H2O2 reacts to form 2H2O plus O2.

Let's have a check for understanding, which statement best describes a catalyst?

Choose from this selection.

A, it is a chemical that is left over at the end of a reaction.

B, it is a chemical that speeds up the rate of a reaction.

C, it is a chemical that speeds up the rate of a reaction without itself being used up.

D, it is a chemical that changes the rate of a reaction.

Pause here while you decide which statement best describes a catalyst.

Well done if you selected answer C.

Indeed, it is a chemical that speeds up the rate of a reaction without itself being used up.

This statement describes a catalyst.

Catalysts are specific to particular reactions.

Different reactions require different catalysts.

Different catalysts were added to the same volume of hydrogen peroxide, iron oxide, copper oxide and manganese dioxide.

A drop of washing up liquid was added to help show which experiment produced the most oxygen gas.

Pause it while you watch the video clip of the experiment.

So you've watched the video clip of the experiment, and here are the results.

Manganese dioxide is the most effective catalyst, as lots of oxygen was quickly produced.

It was quite exciting to watch the experiment.

Iron and copper oxide would not be good choices of catalysts for this reaction.

They did not speed up the reaction.

This confirms that catalysts are specific to particular reactions.

Let's have a check for understanding.

True or false, metal oxides are used as catalysts for all chemical reactions?

Pause here while you decide, is this statement true or false?

Well done if you selected false.

And now I'd like you to justify your answer by choosing from one of these two statements.

A, catalysts are specific to particular reactions, or B, a catalyst can be used to speed up several different reactions.

Pause here while you decide which of these statements justifies your earlier answer.

Well done if you selected statement A.

Indeed, catalysts are specific to particular reactions.

This statement justifies your earlier answer.

Catalysts have important applications in everyday life.

Take a look at this image of exhaust fumes from a petrol or diesel engine.

The combustion engine, used in many vehicles, pumps out toxic and polluting gases into the atmosphere.

Fitting a catalyst to the exhaust system reduces the polluting gases.

The toxic and polluting gases produced in an engine include carbon monoxide and carbon particulates from incomplete combustion of the fuel.

Nitrogen oxides, Nox, formed because high temperatures cause nitrogen in the air to react with oxygen.

A catalyst fitted to a combustion engine exhaust system is called a catalytic converter.

It is made from a transition metal, such as platinum or rhodium.

When a catalytic converter is fitted, chemical reactions speed up and less harmful gases are produced.

That's a very important part of the exhaust system.

And we can see an exhaust system in this image on the screen.

In a car's exhaust system, the catalytic converter speeds up the following chemical reactions.

The word equation is that carbon monoxide and oxygen react to form carbon dioxide, and that's using a platinum catalyst.

And the chemical symbol equation is 2 CO plus O2 react together to form 2CO2, and that's using a platinum catalyst.

And then we have nitrogen oxide and carbon monoxide react together to form nitrogen and carbon dioxide, and that's with a platinum catalyst.

And the chemical symbol equation is 2NO plus 2CO react to form N2 plus 2CO2 using a platinum catalyst.

So these are the chemical reactions which are speeded up by a catalytic converter in a car's exhaust system.

Maybe we can think about that next time we're being driven in a car.

Catalysts are used in industry to ensure that the product is made efficiently and is cost effective.

Many fertilizers are made from ammonia-based chemicals.

Here we can see an ammonia-based fertilizer.

Ammonia is produced from nitrogen and hydrogen in the Haber process, which uses an ion catalyst to speed up the rate of the chemical reaction.

Nitrogen and hydrogen react to form ammonia using an ion catalyst.

The ammonia, however, can also react to form nitrogen and hydrogen.

This is a reversible reaction.

This is also shown in the chemical symbol equation, 2N plus 3H react to form 2NH using an iron catalyst.

As it's a reversible reaction, this can also go the other way, 2NH can react to form 2N and 3H using an iron catalyst.

Let's have a check for understanding.

Catalysts have many applications because, choose from this selection.

A, they make chemical processes more efficient by speeding up chemical reactions.

B, they make chemical processes more cost effective.

C, the same catalyst can be used for many different chemical reactions.

D, they can be reused.

Pause here while you decide why catalysts can have many applications.

Well done if you selected A, B, and D.

Catalysts have many applications because they make chemical processes more efficient by speeding up chemical reactions, they make chemical processes more cost effective, and they can be reused.

And now it's time for your first task.

I would like you, one, to write a definition for the following terms, chemical reaction and catalyst.

And two, a class carried out an investigation to find a suitable catalyst for a chemical reaction, which produced a gas.

They added a different chemical to each beaker, and here are the results.

We can see chemical A, B and C.

I'd like you to, A, answer which chemical was the best catalyst, B, give a reason for your answer, and C, explain, why didn't all the chemicals catalyze the reaction?

So pause here while you have a go at this multi-stage task.

I'll see you when you're finished.

So how did you get on with that task?

First of all, writing a definition for the following terms, chemical reaction and catalyst.

Perhaps you said something like this.

A chemical reaction is when atoms are rearranged to make new products and changes can be observed, e.

g.

bubbles of gas forming.

And a catalyst is a chemical that speeds up the rate of a reaction without itself being used up.

And for the second part of your task, which chemical was the best catalyst?

Chemical C.

And perhaps you gave a reason for your answer, like this.

More bubbles were produced, as seen in the beaker, suggesting that the chemical reaction was occurring faster at a quicker rate.

And C, why didn't all the chemicals catalyze the reaction?

Perhaps you said a catalyst is specific to a particular reaction.

Different reactions require different catalysts.

Well done if you answered the questions in this way.

And now for the third part of your task, use all of the following words to complete the sentences below to explain why petrol and diesel cars have a catalytic converter fitted to their exhaust systems.

Here are the words, speed up, pollutants, carbon monoxide, chemical reaction, nitrogen oxides.

And the sentences.

A combustion engine produces toxic gases, such as.

And a catalytic converter is fitted to.

So pause here while you have a go at this part of your task.

Good to be back with you.

How did you complete those sentences?

Perhaps like this, a combustion engine produces toxic gases, such as carbon monoxide and nitrogen oxides, which are pollutants.

And a catalytic converter is fitted to the engine exhaust system to speed up the chemical reactions and reduce the amount of toxic gases going into the atmosphere.

Well done for having a go at this part of your task.

And now we're onto our next learning cycle, enzymes.

An enzyme is a biological catalyst made of protein that speeds up reactions in living cells.

They're not used up in the chemical reaction.

An enzyme has a specific shape and an active site where the chemical reaction takes place.

And here's a simplified diagram of an enzyme showing the active site.

Let's have a check for understanding.

True or false, an enzyme is a biological catalyst?

Pause it while you decide, is this statement true or false?

Well done if you selected true.

And now I'd like you to justify your answer by choosing from one of these two statements.

A, it is a transition metal that can speed up a chemical reaction in industrial processes, or B, it is a molecule that speeds up a chemical reaction in living cells.

Pause here while you decide, which statement justifies your earlier answer?

Well done if you selected statement B.

Indeed, this justifies your earlier answer.

In the digestive system, the enzyme amylase is used to speed up the breakdown of large starch molecules into smaller glucose molecules, as we can see on the screen here.

This chemical reaction takes place in the active site of amylase.

The starch molecule is called the substrate.

During an enzyme reaction, the substrate reactant binds to the active site.

The chemical reaction takes place and is catalyzed here.

The products are released and the enzyme is reused.

Enzymes are specific to particular reactions.

For the reaction to be catalyzed, the substrate, the molecule or group of molecules, must fit into the active site.

A lock and key is often used to model an enzyme.

Only the correct-shaped key will open the lock.

Only the correct-shaped substrate will fit the active site.

Let's have a check for understanding.

A lock and key is often used to model an enzyme.

What does the key represent?

Choose from this selection.

A, the enzyme, B, the active site, or C, the substrate?

Pause here while you decide.

Well done if you selected answer C, the substrate.

Catalase is an enzyme found in nearly all living things exposed to oxygen.

It speeds up the decomposition of hydrogen peroxide.

The word equation for the decomposition of hydrogen peroxide is that hydrogen peroxide decomposes to water and oxygen.

And the chemical equation for this reaction is 2H2O2 decomposes to form 2H2O plus O2.

Hydrogen peroxide has the potential to harm living cells, so it needs to be removed.

This is done by speeding up the decomposition reaction.

Potatoes contain catalyze.

We can investigate the rate of decomposition at different temperatures and learn more about enzymes.

Here's the equipment required to investigate catalase.

A potato, a cork borer to give us some potato samples, hydrogen peroxide, test tubes, washing up liquid, a beaker for hot water, and some iced water.

And now I'd like you to watch the video below, observing the effect of temperature on the rate of reaction of catalase enzyme from potatoes to learn more about enzymes and temperature.

So pause here while you watch the video.

Now you've watched the video, let's consider the results.

At which temperature does catalase work best, cold, room temperature or hot?

Pause here while you decide.

Well done if you said room temperature.

And now it's time for your next task.

One, I would like you to define an enzyme, and then 2a, label the diagram, and 2b, name an enzyme, and three, a lock and key is often used to model an enzyme, describe why it is a good model.

So pause here while you have a go at this multi-stage task.

I'll see you when you're finished.

It's good to be back with you.

How did you get on with that task?

So defining an enzyme.

An enzyme is a biological catalyst that speeds up reactions in living things.

Did you label the diagram in this way, substrate, active site, and enzyme?

Naming an enzyme, perhaps you said amylase or catalase.

And describing why the lock and key is a good model for an enzyme.

Perhaps you said something like this.

The lock represents the enzyme.

The keyhole represents the active site.

The key represents the substrate.

Only the correct-shaped key will open a lock.

Only the correct-shaped substrate will fit the active site.

The lock can be used many times and so can the enzyme.

Well done for having a go at these parts of the task.

And four, proteins are digested in the stomach and small intestine.

Protease enzymes break down proteins into amino acids.

Pause here while you complete the diagram.

It's good to be back with you.

So how did you get on with that task?

Did you complete the diagram in this way?

Protease enzymes break down proteins into amino acids.

In our lesson "Catalysts," we have covered the following.

A catalyst speeds up a chemical reaction without being used up or chemically changed.

Catalysts are specific to particular reactions.

Different reactions require different catalysts.

Enzymes are biological catalysts that speed up the reactions in living cells.

Well done everyone for joining in with this lesson.

It was so interesting to explore catalysts, chemical reactions, and to find out how catalysts are used in the body, in industry and in car engines.

I really enjoyed teaching you, and I hope you enjoyed this lesson too.

I look forward to seeing you at another lesson soon.

Until then, stay curious.