Secondary Science KS3

The lesson we are deconstructing is a KS3 lesson on Neutralisation, which is lesson 7 in the Chemical Reactions topic.

Neutralisation

Science

The quiz will test your knowledge learned in the previous lesson, as well as previous lessons

Tick FOUR signs of chemical changes

What product is formed when zinc reacts with oxygen?

Jack added universal indicator to an unknown liquid. It went purple. What does this mean?

What salt will form when aluminium is added to nitric acid?

What is the word equation for copper reacting with hydrochloric acid?

Revision 1

﻿Hi everyone, and welcome back to Chemical Reactions with me, Mrs. Walsh. I hope you're feeling good today and you're ready to learn. In this lesson, we're going to be looking at neutralisation reactions. For this lesson, you're going to need a piece of paper and a pen to jot your answers down with. You're also going to need a pencil and a ruler to jot down some of the diagrams that'll pop up later in the lesson. If you haven't got these items to hand, don't worry, just pause the video here, grab what you need and as soon as you're ready, hit play and we'll get started. All set? Brilliant. Now, a couple of quick reminders as always before we get going. Make sure you're in a nice distraction-free environment, and this can be achieved by turning your phone off or putting it on do not disturb. Make sure you have a go at all the activities that I've set for you. You can always pause the video if you need to, if you want to go back to any material that you've missed, or you just simply didn't get it the first time round, that's absolutely fine. You can take this lesson at your own pace, the most important thing is that you don't give up. So, what does our lesson look like? We're going to start off by looking at what actually happens during a neutralisation reaction. Then going to explore some acid and alkaline reactions and look at what products are formed. We're then going to look at predicting the salt names from the products when an acid and alkali react. And always, there's an end of lesson quiz where you can test yourself on the knowledge gained in this session, and also some of your prior knowledge. So, let's get things started get you warmed up with a short quiz. Are you ready? Remember, you don't need to write any of this down, you just need to shout the answer out or point to the correct answer on the screen. So, what does this symbol mean? Three, two, one. It means corrosive. Well done if you got that correct, well remembered. What gas is produced when a metal reacts with an acid? Three, two, one. It is hydrogen, well done if you've got that. What type of salts do sulfuric acid produce? Three, two, one. It is sulphates, well done if you got that one as well. What type of salts do hydrochloric acid produce? In three, two, one. They produce chloride salts. And the last one, what is the test for hydrogen? Three, two, one. A lit splint pops. Well done if you remembered all those. Right, I hope you're feeling warmed up now, let's get cracking on with the lesson. Okay, why is baking soda used on bee stings? Any idea? We're going to have a look at this a little bit later on in our lesson, but there is a saying bicarb for bees, vinegar for wasps. So, why is baking soda used on bee stings? Let's find out. In the first part of our lesson today, we're going to look at what actually happens in a neutralisation reaction. So, here is the pH scale. This was covered in lesson four when we looked at the pH scale. Now, if you can recall, over on the left-hand side we have acids, and on the right-hand side we have alkalis. We're just going to top up this little bit of knowledge and give you a little bit extra scientific information about this. Now, what makes something acidic is a number of H+ particles it has. An acid contains H+ particles, or hydrogen particles. Alkalis on the other hand contain hydroxide particles, or OH- articles. The more hydrogen particles a substance has, the more acidic it will be. And the same is true for alkalis, the more hydroxide particles there are, the stronger the alkali will be. So, when an acid alkali come together, the hydrogen particles from the acid combine with the hydroxide particles from the alkali, H+ and an OH-, it creates water. And this is shown in the equation below, this is neutralisation. I'd like to pause the video here whilst jot this down in your notes. When you're done hit play, we'll have a look at an animation of this. All set? Brilliant. So let's have a look at what happens during neutralisation. So here we have our acid, our strong acid rather and our strong alkali. We add our alkali to our acid. Our acid is no longer red and is now green, so what does that indicate about the substance? That's correct, it is now neutral. Want to see that one again? Okay. We got a strong acid and strong alkali, add our alkali to our acid, and a neutral substance is produced. You got it that time? Okay, let's do a quickfire quiz and see what you can recall. Again, you don't need to write these answers down, you just need to shout out the answer or point to the correct answer on the screen. So, acids contain what? Three, two, one. It is H+ particles or hydrogen particles. Well done. Alkalis contain? In three, two, one. That's correct, hydroxide particles or OH- particles. Strong alkalize contain? Three, two, one. Lots of hydroxide particles. Strong acids contain? Three, two, one. That's right, lots of hydrogen particles. In a neutralisation reaction blank is formed. What should go in that space? Three, two, one. That's correct, it's water. So, the H+ or the hydrogen particles from the acids combined fully with the OH- or the hydroxide particles from the alkalis, and therefore water is made, and that is neutralisation. Okay, so water is just one of the products that's formed in an acid and alkaline reaction. Let's explore these reactions a little bit further, and then we're going to advance our knowledge by trying to predict name of the salt which is the other products that comes out of this reaction. So, put this down as a subheading on your page and let's move forward. Let's have a look at the reaction between sodium hydroxide and hydrochloric acid. Now, I don't want you to write anything down for a moment, I just want you to listen. So, put your pen down on the desk and put all of your focus on the screen. Brilliant. So, in the reaction between sodium hydroxide and hydrochloric acid, you have the following. Here is sodium hydroxide, and here is hydrochloric acid. When these two substances undergo a chemical reaction a new substance is formed, this is known as sodium chloride. The water is produced from the hydroxide group from the alkali, and the hydrogen from the acid. Can you spot where these are in this diagram? Well done if you spotted them here. Here is the formation of water. I'd like you to pause the video here for a moment, and I'd like to jot this particle diagram down. Make sure you include the word equation at the bottom of the screen. When you're all you set, resume the lesson and we'll carry on. Here is the general equation when an alkali, which is a metal hydroxide, reacts with an acid, you will always get a salt plus water. We're going to look at the name of that salt later on 'cause they're all different depending on the chemicals used. But as a general rule, when an alkali, which is a metal hydroxide, reacts to the acid, you get a salt and water. Underneath your particle diagram, please jot this down. You got it? Fantastic, let's look at another acid and alkali reaction. This time we're going to react lithium oxide and hydrochloric acid. So, here is lithium oxide, and here's hydrochloric acid. These two will react to form a new substance, and this substance is known as lithium chloride. And here is the water formation. A quick revision point, how do we know a chemical reaction is taking place? Brilliant, 'cause the atoms are still there, what went in has come out, it's just rearranged and it's now the atoms are now bonded to a different substance. Well done if you spotted that. Another quick revision point, is mass conserved? Count up the particles on each side of the arrow and see if they're equal. Brilliant, they are, conservation of mass is achieved in this equation. Well done. What I'd like to do now is I'd like to jot down this particle diagram for the reaction between lithium oxide and hydrochloric acid, and make sure you include the green word equation at the bottom as well. Use your pencil to do this. When you're done, we'll have a look at the general equation for these alkali-acid reactions, All set? Brilliant. Underneath your diagram, I'd like you now to write out the bolded general equation. So here you can see when an alkali, that's a metal oxide, reacts with acid, it too produces a salt plus water. So there's very little difference between a hydroxide alkali and an oxide alkali, they both produce salt plus water when reacting with an acid. So, pause the video for a moment and jot that down. All set? Brilliant, we're going to look at one final acid and alkali reaction. This time, we're going to look at the reaction between magnesium carbonate and hydrochloric acid. So, here is magnesium carbonate, it's going to react with hydrochloric acid. They will form a new substance, which is magnesium chloride, but carbon dioxide is also given off as well as water. Where is this carbon dioxide come from? Well, it's quite simple really, alkali has now got this carbonate group. Therefore, in addition to the salt and water, we get a third product, which is carbon dioxide. For the final time, please pause the video here and jot down this particle diagram for the reaction between magnesium carbonate and hydrochloric acid. And once again, make sure you get the words equation underneath. When you're all set, hit play, and we'll look at the general equation for this reaction. All set? Brilliant. Finally, can you jot down the bolded general formula for the reaction between an alkali that is a carbonate and an acid. You'll see here that the salt plus water is produced, but in this instance, there is also that third product, which is carbon dioxide. Excellent, okay. So, we know that in each of these reactions, salt and water came out. Now, we've looked at where the waters come from at the very start of our lesson. So, let's have a go at trying to predict the names of salts that will come out. Just like when the metal and acids react, when we have an alkali and an acid react, the naming rules still apply. This time, the first name of the salt is taken from the metal in the alkali, just as with the previous lesson if hydrochloric acid is used then a chloride salt is formed, if sulfuric acid is used then a sulphate salt is formed, and if nitric acid is used then we have a nitrate salt that is produced. If you need to drop these rules down in case you've not got them in your notes, I will suggest you do that so you've got a quick reference point for the rest of this lesson. You're going to need them, there's quite a few activities that rely on this information. If you're feeling quite confident that you don't need it then you can move on. Let's practise with this first equation. We've got magnesium hydroxide and hydrochloric acid, what's the name of the salt produced? Well, let's use our rules. The first name of our salt is the metal from the alkali. Well, that's magnesium, so therefore the fast name must be magnesium. The surname of the salt comes from the acid that I've used, and as I can see from my equation, hydrochloric acid is used. So therefore, the surname for my salt must be chloride. Is our equation complete? No, it's not, what else has given out? Brilliant, can't forget the water, this the whole part of the neutralisation reaction. Now, our equation is complete. Excellent work. Let's look at another example. Here we have copper oxide and blank to make copper nitrate and water. Now, this time we've got the salt name, but we need to work backwards to see what acid was used. Well, let's just double-check. We've got copper, which is our metal, and nitrate is the surname. Well working backwards, if nitrate is the surname we must have used nitric acid to start. And we did. How are those? Are you feeling okay with them? Fantastic And our equation is complete because we've got water on the end. How are you feeling with those? Are you feeling quite confident? Fantastic. Let's try one more. This time we've got magnesium carbonate and we've got two blank spaces in our equation. The first blank space is for the acid used, and the second blank space is for another product that's produced. Let's figure out the acid first. Magnesium carbonate goes to make magnesium sulphate, so we know magnesium is the metal used. The surname of our salt is sulphate, so what acid was used? Well done for spotting that, it must have been sulfuric acid. Well, what's this other product? What else has been formed? Well, if we look at the equation, we've got this carbonate. So, if a carbonate is present, what other product is produced? That's correct, we also get carbon dioxide given off. Well done. Right, that's about all the practise I think you're going to need. So, if you're feeling confident move on now to the independent activity. If you feel like you need to watch these examples again, don't worry, just rewind the video and watch them as many times as you need. And when you're feeling super confident, have a go at the independent activity. Here is your independent practise. I want you to pause video here, and I want you to copy and complete each of the different reactions down in your book. Be careful, you might be missing one or more from each row. When you think you're done, hit play and we'll go through the answers together. Here are the answers for the independent practise. You might wish to pause the video here whilst you check and correct against your own work. For this answer here, there is a choice of answers you could have had. The reason why it could be either zinc oxide or zinc hydroxide and not zinc carbonate is because no carbon dioxide was produced, only zinc nitrate and water are produced. Therefore, it can't possibly be zinc carbonate. Give yourself a tick for each correct row, it's a mark out of seven. How did you do? A really big well done if you managed to get five or more rows correct. Fantastic work. Right, time for one final independent activity, and it brings us back to the question we asked at the start. I introduced this saying right at the start of the lesson bicarb for bees, vinegar for wasps. I'd like to explain the science behind this common saying. There's some extra information in the box on the left, and there are some sentence stems in the box on the right. Utilise both of these to formulate your answers. Please pause the video to complete your task, and when you think you're done, hit play and we'll go through the answers together. All set? Okay, let's see what you should have written. Please pay particular attention to the orange highlighted sections. A bee sting must be slightly acidic, therefore a weak alkaline, such as bicarbonate of soda, will neutralise the bee sting. A wasp sting must be slightly alkaline, therefore a weak acid, such as vinegar, will neutralise the wasp sting. How did you do? Did you spot all those points? Fantastic work if you did, brilliant. So, why is baking soda used on bee stings? Because bicarbonate of soda neutralises the sting from the bee. Just something for you to bear in mind if you're ever stung by a bee, or a wasp for that matter. And that's the end of our lesson, so let's summarise the key points. Acids contain hydrogen particles, or H+ particles. In a strong acid there are lots of these hydrogen particles. Alkalis however contain hydroxide particles, or OH- particles. In strong alkalis, they will contain lots of these hydroxide particles. In a neutralisation reaction, the hydrogen of the acid and the hydroxide of the alkali come together in order to form water. When all the hydroxide particles have completely bonded to all the hydrogen particles, the substance becomes fully neutralised. However, if a weak acid comes into contact with a strong alkali, there's simply not enough hygiene particles to combine with the hydroxide particles, and therefore some remain in the solution, and this just makes the alkali weaker, but it does not fully neutralise it. The same is true, if we work the other way round, the strong acid can not be neutralised by a weak alkali. When an acid and an alkali react, the same products come out, a salt plus water. The only addition is when the alkaline is a carbonate, and the extra product form is carbon dioxide. Just like when metals react with acids, the name of the salt can be predicted. The first name of the salt takes its name from the metal in the alkali, and the surname of the salt comes from the acid that is used. If hydrochloric acid is used, the salt is a chloride, if sulfuric acid is used, the salt is a sulphate, and if nitric acid is used, the salt is in nitrate. And that's it, brilliant. A really big well done on all that you've achieved in this lesson today. Fantastic work. Now, don't forget to click next and complete the end of lesson quiz so you can test yourself on the knowledge gained in this session, and also some of your prior knowledge. All that's left for me to say now is thank you, take care and enjoy the best of your learning for today. See you next time.

This quiz will test your understanding of today's lesson and some prior knowledge too.

What is the pH of a neutral solution?

What is the pH of acidic solutions?

What is the pH of alkaline solutions?

What two products are always made in a neutralisation reaction?

What products are made when aluminium oxide reacts with sulfuric acid

What products are made when zinc carbonate reacts with hydrochloric acid?

What is the pH of the products from the previous question?

Revision: which gas is produced when zinc reacts with hydrochloric acid?

Describe what happens to the pH when acids are added to alkalis or vice versa

Represent the reaction of acids and alkalis using word equations

Name the salt produced in acid alkali reactions

This lesson focuses on what happens during neutralisation when an acid and an alkali react, how to represent this as a word equation and how to predict the name of the salt produced in this reaction.

ITT: Neutralisation

Secondary Science KS3

1. Original Oak Lesson