Welcome to today's lesson on Chemical reactions: acid and metals.

It's part of the unit, acids and base.

My name's Mrs. Mytum-Smithson, and together, we're going to work through this lesson step by step, and we're going to look at acids and metals reacting together.

By the end of this lesson, you should be able to describe what happens when an acid reacts with a metal, and write word and symbol equations for these reactions.

The keywords for today's lesson are effervescence, chemical test, corrosion, acid, metal salt.

On the next slide, there's some sentences that include these keywords.

So pause the slide whilst you read those.

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

Today's lesson consists of two learning cycles, acid and metal reactions and testing for hydrogen.

So firstly, let's start with acid and metal reactions.

Let's get going.

Different metals have varying reactivity with acids, and you can observe these and compare the reactivity.

So here's a metal.

This is magnesium, and it's reacting with an acid.

You can look at the bubble formation, so the rate of those bubbles being formed.

Sometimes, we can call this effervescence, so that's a new word for many people today.

And we can look at the temperature of the reaction mixture.

So this can increase as the reaction is exothermic.

We can also look at, so we can also observe the corrosion of the metal.

So that's when the metal is worn away and reduces in size.

Now, we've got a quick check for understanding for you.

How would you observe that a gas is being produced in a reaction? So what I want you to do is select all the answers that are correct here, so select all that apply.

So you would see bubbles being formed in the liquid.

The liquid would change colour.

The liquid would be effervescing.

The liquid would start to fizz.

So pause the video for some thinking time, then press play when you've got your answer or answers.

Well done if you said you would see bubbles being formed in the liquid, the liquid would be effervescing.

Remember that's our science word for fizzing, and the liquid would start to fizz.

So well done if you managed to get all of those three correct.

Well done.

I've got another check for understanding now, which is the most reactive metal? So I want you to look at these pictures, and tell me which is the most reactive metal.

Pause the video while you do that, and then press play when you've got your answer.

Well done if you said A was the most reactive metal.

If you have a look, B's only got two bubbles.

C's got a few more, but the most reactive metal is A, because that's got the most bubbles.

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

When a metal reacts with an acid, the products are metal salt, which is soluble in the reaction mixture.

So that will dissolve into the reaction mixture.

Hydrogen gas, which can be seen as bubbles in the reaction mixture.

So here's a general equation.

So metal plus acid makes metal salt plus hydrogen.

Here's a specific example.

So we've got magnesium reacting with nitric acid.

So we say magnesium plus nitric acid makes magnesium nitrate, that's the metal salt, plus hydrogen.

So the metal salt will depend on metal and acid that is used.

So here, you can see that we've got magnesium as a metal, and that gives the name for the first part of the metal salt, so that's magnesium.

And then the second part of the metal salt name comes from the acid.

So in this case, we've got nitric acid, and that's going to produce that name of nitrate at the end.

So our metal salt gets its name from the metal used and that acid used, but we always produce hydrogen.

That doesn't change in a metal and acid reaction.

A quick check here, what is the general equation for a reaction between a metal and an acid? Is it metal gives acid plus metal salt plus hydrogen? Is it metal plus acid gives metal salt and hydrogen? Is it metal plus acid gives metal salt plus carbon dioxide? Is it metal plus acid plus hydrogen makes metal salt? So pause the video while you decide which equation it is.

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

So well done if you said metal plus acid makes metal salt and hydrogen.

Well done if you got that one correct.

Different acids produce different types of metal salts.

So here, we've got a table, and this includes the name of the acid, the name of the metal salt ending, and the chemical formula of the acid.

So you can see if we using hydrochloric acid, we would make metal salts ending in chloride and the chemical formula of the acid is HCl.

Then we've got sulfuric acid.

Sulfuric acid makes metal salts called sulphates, and the chemical formula for the acid is H2SO4.

Then we've got nitric acid.

Nitric acid makes nitrate salts, and the chemical formula for the acid is HNO3.

So here's another example.

We've got magnesium plus hydrochloric acid, makes magnesium chloride plus hydrogen.

So we can see here, we've got this metal name here, and this gives the first part of the metal salt name, and then we've got the hydrochloric acid.

So we're going to make a chloride salt, and we always produce hydrogen.

So we've got iron plus sulfuric acid makes iron sulphate and hydrogen.

So remember, the first part of the metal salt name comes from the metal, so that's iron, in this case.

And the second part comes from the type of acid.

So sulfuric acid makes sulphates.

So you can see that there's a link between the name of the acid and the name of the metal salt ending.

Now, we're going to have a look at some chemical equations for the reactions of metals and acids, and how they're written.

So we've got our equation here.

So magnesium and hydrochloric acid makes magnesium chloride and hydrogen.

So here's the symbols.

The symbol for magnesium is Mg.

The symbol for hydrochloric acid is HCl, and they're going to react together to make that metal salt.

So the symbol for that metal salt is, so it's MgCl2 plus hydrogen, which is H2.

So let's take a closer look at this.

So we've got the magnesium there, that is the first part of the metal salt.

And then we're going to have a look at the second part of the metal salt, and that's a chloride.

So we've got magnesium chloride.

So we've got the Cl that moves across there when the atoms are rearranged.

And then you can see there that this is where the hydrogen gas comes from.

So we've got the hydrogen there, H2.

Let's have a look at another one.

So iron plus sulfuric acid makes iron sulphate plus hydrogen.

So we've got the iron plus sulfuric acid, which is H2SO4, and we're going to make with this iron sulphate and hydrogen gas.

So let's have a look.

So we've got the iron there that makes the first part of the iron, sorry, the metal salt.

Then we've got the second part which is the sulphate part, which is SO4.

And, of course, the hydrogen is then going to come from the first part of that acid, H2.

Here, I've got the true or false.

True or false, zinc plus nitric acid makes zinc chloride plus oxygen.

Is that true or is that false? Pause the video, once you decide, then press play, and I'll tell you if you're right or not.

Well done if you said that that reaction was false.

Let's have a justification for that now.

Nitric acid and metals react to form metal nitrates and hydrogen.

Nitric acid and zinc reacts to form metal chlorides and carbon dioxide.

Pause the video while you decide which statement's correct.

Then press play, and I'll tell you if you're right or not.

So well done if you said nitric acid and metals react to form metal nitrates and hydrogen.

Well done.

What I want you to for this one now is the symbol equation for the reaction between zinc and hydrochloric acid to produce zinc chloride and hydrogen gas is? So I want you to select which one of those equations matches up with the description in the question.

Pause the video whilst you do that, and then press play and I'll go through the answer with you.

So well done if you said C, zinc plus HCl, so that's hydrochloric acid make zinc chloride plus hydrogen gas.

So well done if you got that right.

For part one, what I'd like you to do is take a look at these images below, and order the different metals reacting with the acid from the most reactive to the least reactive.

Then I want you to explain how you decided on the order of reactivity.

Then I want you to name the gas produced.

Then I want you to tell me what else could you do to assess the reactivity of the metals.

Pause a video while you complete parts one to four, then press play, and we'll go through the answers.

So well done if you've got these metals in the correct order.

So the most reactive was metal B, then metal C, then metal D, and finally, metal A.

In terms of how you decided that, you should have had a look and seen how many bubbles were being produced.

So the more effervescing you see, or the more fizzing you see, or the more bubbles, the more reactive the metal.

And the bubbles are filled with hydrogen gas.

And what else could you do to assess the reactivity of the metals? You could measure the temperature of the reaction mixture, and the higher the temperature increase, the more reactive the metal.

What I want you to do for this task is complete the missing words in the following word equations.

There's a table of information here that contains the name of acid and the name of metal salt endings.

And all you've got to do is complete these equation.

Zinc plus sulfuric acid makes something sulphate plus hydrogen.

Magnesium plus nitric acid makes something plus hydrogen.

Something acid makes lead sulphate plus something.

Zinc plus hydrochloric acid makes zinc chloride and something.

Iron plus something acid makes something chloride.

Pause the video while you complete this task, then press play and we'll go through the answers together.

Well done for completing that task.

Let's go through these equations now, and see how many you got correct.

So zinc plus sulfuric acid.

So when sulfuric acid is involved, it's going to make sulphates, and the metal name for that comes from the metal.

So zinc plus sulfuric acid is going to make zinc sulphate plus hydrogen, 'cause hydrogen is always made in a metal plus acid reaction.

Then we've got magnesium plus nitric acid makes magnesium nitrate.

Remember, the first part of the metal salt comes from the metal, and the second part comes from the acid used.

Let's have a look at C now.

So we've got lead plus sulfuric acid makes lead sulphate and hydrogen, because hydrogen is always made in acid and metal reactions.

We've got zinc plus hydrochloric acid makes zinc chloride and hydrogen.

And then we've got iron plus hydrochloric acid, 'cause hydrochloric acid makes chlorides.

We've got iron as the metal, so that means that iron chloride is the salt made.

And then plus hydrogen, because we always make hydrogen in these reactions between metals and acids.

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

You're working really well.

What I want you to do for this part is complete the symbol equations for your answers from part five.

So here's the word equations from part five, the first three, and here's the symbol equations with some gaps that you need to add in and complete.

Pause the video whilst you do that and press play.

And then we'll look at the questions for D and E.

Here's the second part of part six, task A.

So here's D and E.

So what I want you to do now is complete these missing blanks.

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

Well done for completing that task.

So here's our equation.

We are missing the symbol for sulfuric acid.

So that's H2SO4, and that completes that equation.

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

So this is magnesium.

So magnesium plus nitric acid mix, magnesium nitrate.

And the other thing it's going to make is hydrogen gas, so it always makes hydrogen, and the symbol for hydrogen is H2.

Then we're gonna have a look at this lead one.

So we've got lead, and then we need the symbol for sulfuric acid.

So that's H2SO4, and it's also makes hydrogen, as well.

So we need to put the symbol for hydrogen which is H2.

Well done if you've got A, B, and C correct.

Let's now have a look at D and E.

So here, we've got zinc plus, and then we're looking for the symbol for hydrochloric acid, which is HCl.

And then that makes zinc chloride, and we're looking for the symbol for hydrogen here, so H2.

Capital H, and then subscript number two.

And finally, E, we're looking for the symbol for iron, which is Fe, the symbol for hydrochloric acid, which is HCl.

And that completes our equation making iron chloride plus hydrogen.

So well done if you've managed to get all of those symbol equations correct.

You've done really well.

Now, we're moving on to our second learning cycle of testing for hydrogen.

The chemical test for hydrogen gas is to introduce a lit splint, which will make a squeaky pop.

We are going to watch a video of this now.

<v Narrator>Okay, so this is magnesium</v> and the hydrogen pop.

(Bunsen burner hissing) (lit splint popping) <v ->So let's recap that video.

</v> So the first thing you're going to do is you're going to add metal to the acid.

Then you're going to hold an empty test tube over the reaction mixture.

Hydrogen gas is less dense than air, so it will rise up into that empty test tube.

So please make sure that you continue to hold that test tube upside down.

Once you've collected some hydrogen gas, you're going to ask your partner to hold a lit splint near the test tube opening, and you're going to listen for that distinctive squeaky pop.

Some of the reactions between acids and metals are exothermic, and they give off enough heat, so that you can feel the temperature increase through the test tube, or you could measure it using a thermometer.

So here's a picture here of a metal reacting with acid.

And you can see there, if you just place your fingers on the outside of the test tube, you might be able to feel a temperature increase through that test tube.

What is the chemical test for hydrogen? Do you place a glowing splint in the test tube, and watch to see if it relights? Do you bubble the gas through lime water, and see if the lime water goes cloudy? Do you hold a lit splint near the test tube opening, and listen for a squeaky pop? Or do you place a damp piece of blue litmus paper in the test tube, and see if it bleaches? So pause the video whilst you decide what the chemical test for hydrogen gas is, and then press play, and I'll tell you if you selected the right one.

Well done if you said hold a lit splint near the test tube opening, listen for a squeaky pop.

Well done if you got that one correct.

Some reactions between acids and metals are so exothermic that you can hear the temperature increase from the test tube with a squeaky pop.

Feel a temperature decrease through the test tube, feel a temperature increase through the test tube.

Pause a video while you decide your answer, and then press play, and I'll tell you if you're right or not.

Well done if you said C, you should be able to feel a temperature through the test tube with an exothermic reaction.

Now onto task B, this is a practical task.

What I want you to do is react hydrochloric acid with different metals, and record your observations.

So I want you to complete your results table.

So here's the results table.

We've got four metals that we're going to test, copper, magnesium, iron, and zinc.

You're going to write down your observations.

So that's what you see, and that's what you feel.

And then you're going to say, does it give a positive hydrogen gas test? And then you're going to order them in order of reactivity.

So you're going to go from the most reactive, you're going to write one, to the least reactive, you're going to write four.

So here's your method that you're going to use.

You're going to add metal to the acid.

You're going to hold the empty test tube over the reaction mixture.

You're going to feel the outside of the test tube for a temperature increase.

And then you're going to test the gas with a lit splint, and you're going to listen for a squeaky pop.

So pause the video while you carry out that practical activity, completing your results table.

Then press play and we'll discuss your results.

So what I want you to do is I want you to make sure that you've done the order of reactivity based on observations.

So one being the most reactive, and four being the least reactive.

And I also want you to write the word and symbol equations for each reaction that takes place.

Pause the video while you do that, then press play, and we'll discuss the results together.

So well done for completing that practical.

Your results might look a little bit like this.

So you might not have seen any bubbles formed.

So there should have been no bubbles formed, and no reaction with copper.

You should not have got a positive gas test, and that would be the least reactive metal.

Then we've got magnesium.

You should see lots of bubbles formed, so effervescing.

And the test tube, you should be able to feel from the outside that it gets warm, and that should have given a squeaky pop if you've managed to do that test correct.

So that one was the most reactive, because there were lots of bubbles formed.

And then iron, lots of tiny bubbles formed, and no for a positive gas test.

And then zinc bubbles formed on the surface of the zinc, and not a positive hydrogen gas test there either.

So I've ranked these as two or three.

So you might have got them that iron was more reactive than zinc or you might have got 'em that zinc was more reactive than iron.

Sometimes, it's difficult to see.

For the order of reactivity, it is difficult to see, which is more reactive between zinc and iron.

Other factors such as the size of the metal pieces will affect the rate of reactivity, so I've got iron here, and I've got zinc here.

And you can see that the smaller pieces, and you've got more bubbles produced.

And zinc, you've got a large piece here, and that's got bubbles on the surface.

So as you can see, this is not a fair test.

If you wanted to see for sure which was the most reactive, then you would have to make sure that either all the pieces of iron and zinc were little or all the pieces of iron and zinc were large.

So maybe you want to carry that out another day with your teacher.

Equations for the reactions are given below.

And although you may not have been able to carry out a positive chemical test for hydrogen, the bubbles confirm that a gas was produced just not enough for us to collect to give a squeaky pop.

So we've got magnesium plus hydrochloric acid makes magnesium chloride and hydrogen.

We've got iron and hydrochloric acid makes iron chloride and hydrogen.

We've got zinc plus hydrochloric acid makes zinc chloride and hydrogen.

And we've got copper plus hydrochloric acid, no reaction there.

Here, we've got the chemical equations, we've got Mg plus 2HCl gives MgCl2 plus H2.

Iron, symbol for iron is Fe.

So we've got Fe plus 2HCl makes FeCl2 plus H2, that's a hydrogen.

And then, again, we've got zinc.

So the symbol for zinc is Zn plus 2HCl makes zinc chloride, ZnCl2 plus H2.

And finally, for the copper, there's no reaction at all.

So we are not going to write an equation for that.

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

You've done really well this lesson.

Here's a summary for today's lesson.

When a metal reacts with an acid, bubbles may form, it is exothermic and the metal reduces in size.

Different metals have varying reactivity with acids.

When a metal reacts with an acid, the products are a metal salt and hydrogen gas.

The word equation for a metal and acid reaction is metal plus acid makes metal salt plus hydrogen.

The test for hydrogen gas is to introduce a lit splint, which will make a squeaky pop in hydrogen.

Well done for working really hard this lesson.

I hope that you enjoyed testing the gas for hydrogen and hearing those squeaky pops.

You should now feel much more confident about writing equations, both word and symbol for metals and acid reactions.

I hope to see you again sometime soon.