Not very sensible, is it? But like I we did most of the topic, like we did a lot of lesson than like one lesson. So you felt confident with what you did. Did you have your Marks back from the test? No. All right. Well, we will be going through it a little bit slower. So I don't think that will do any harm. And we can always catch up a little bit during the holidays. We'll catch up anyway, won't we? How long have you got back for Chinese New year? One to two weeks, I think. Okay. So thatwill, give us a couple of lessons to catch up. Right. We won't start with your homework. We'll mark it together if we get time. But let's get going with the lesson first. If we don't mark it together, I'll just do it for you at the end of the lesson. So we are looking at chemical equations today. Let's get the PowerPoint. Okay. Not that one. That one. No, that's the wrong one. Sorry. That one, okay? So we want that one first. Word and simple equations, we want that as well. Yep. And. Okay, let's start. So today's lesson here, chemical equations. Can you read that please? Any objective to understand how to write chemical equations to represent chemical reaction success criteria, to describe what is meant by the term reactant and product, to write word inquestion ation from information about chemical reaction, to write the symbol equation from given formulae including state symbol. Brilliant. So that's what we're doing. So did you cover that? We did like some like magnesium and oxygen is like magnesium oxide. Okay. Alright, a student reacted bicarbonate of soda with vinegar. One of the products of the erection was carbon dioxide, which caused the mixture to bubble. Carbon dioxide has a chemical formula, co two. Is this a chemical or a physical change? It's a chemical change. How many atoms are present in carbon dioxide? Three. Good one. Carbon, two. Oxygen, three. In total, the student carried out the reaction on a top pan balance and noticed that the MaaS decreased y. Because the carbon dioxide gas like escapes. Into the air. Absolutely. So it wasn't trapped. Chemical equations. So when heated, magnesium reacts with oxygen in the air. And we looked at that last lesson and the reaction produces magnesium oxide. So chemical reactions can be represented using chemical equations. What do we call the reacting substances? Reactant? Yep. And you can guess what's coming next. What do we call the substances produced product, right? You definitely know that word equations. So we're going to start with word equations, then we'll go on to symbols. And then if we get time, we will balance them. Okay. So when heated, magnesium reacts with oxygen producing magnesium oxide. What are the reactants? A magnesium and oxygen and the product magnesium oxide. And the word equation would be. Magnesium plus oxygen goes an arommagnesium oxide. Yeah, got it. So we separate the multiple reactions with a plus, and we separate the reactants with an arrow. Magnesium. I'm just wondering why that's decided to put the answer up. Never. Evermind magnesium will also react with hydrochloric acid to produce magnesium chloride and hydrogen. What are the reactants magnesium and hydrochloric acid? What are the products? Magnesium chloride and hydrogen, and then the word equation is decided to give you the answer. Right, naming reactants and products, right? I'll let you read the blue box this time. In order to write a word equation for chemical reaction, we need to know the names of the reactant and product. The chemical name will often be a combination of elements that make it up. If the compound contains the metal, the metal converse in the name. If a compcompound is made from only two elements, the name ends in eyed, right? I'm just going to put that in the chat there, just in case that's helpful later. Can you see where I've put that? Just in the yein, a cluchat in the reaction between magnesium and oxygen, the product is named magnesium oxide, name the product in the reaction between iron and sulfur. Iron plus sofa goes to iron so ate so ate I'd. Yeah p, because it's Yeah, there's no oxygen. Sorry. Yeah, there's no oxygen. That's why it's not sulfate. It's just iron and sulfur. If it was iron sulfur and oxygen, it would be iron sulfate. So I'd when it's just two things. Right. Before we go into that, let's do some practice. So we're going to do a little bit of cutting out, but we are not concerned with the second page at the moment. So we don't want the symbols. We'll keep those for later. So we are just going to do the word equations and then we're going to leave a space for the symbols, and we're going to add that on later. So if you cut out that first one. Youlike, give me the pen. Oh, Yeah, sorry, you good. That's our next one. 12345. I keep clicking the wrong thing today, right? One, two, three, four, five, six, seven, eight. So when you arrange these on the screen, I want you to do the word equation, and then I want you to leave a space underneath so we can add the symbols later. Oh, why do I feel like I've lost my place? Yeah, no, I didn't do think. Yep, hopefully that's everything. You feel like you've done everything. Yeah. Okay. So we can change the side if you want to. Here's all the arrows over here, then we'll put all the pluses. Okay. Why there so many? Yeah. Right, I'll get you started. So you've got zinc and lead up there. So let's get started with those. So let's have zinc plus lead for our first one. And then add your arrow in. Oh, sorry, zinc plus lead nitrate. This is a displacement reaction yethat's it where they swap places. Okay, now that's it. Leave a little space for the symbols. We can make the symbols a bit smaller. So Yeah, Hey, good. Steam, this one reacts with so beryllium plus steam. And then you get a gas. Yeah, beryllium oxide. That was right. And then you get a gas. Oh, where's that gone? Where did that just go? I deleted it. Oh, okay, let's get it again. I'll just cut it. Don't worry, we're really lioutside xide. And then you get a gas which goes pop when you put a glowing splint in it. Do you remember what gas that is? Hygen hydrogen. That's it. Eight plus hydrogen. Right. Super, let's leave a gap. Let's start with copper. And Yeah, that's it. You can work that out from your reactant. Start with potassium hydroxide for your next one. That's it. Well done. Chasing chlorioride. Did you just delete it again? Yes. Was it water? Got it out. Yeah, okay, water. Well, I couldn't like unundo it though. Well, I don't know. I know control z sometimes undoes it. Are you on a mac or a. No, I'm on an iPad. Oh, no, it won't work. I don't know what the shortcut is for that. Magnesium carbonate. Noyou were right before. So this is just about decomposition. So this is just about a chemical breaking down. That's it. Yep. So it hasn't got anything to react with as such. So you would just add heat to it and you would just break it down into its parts, right? We need to save this because we're going to come back to it. Hmm, how am I doing this? This is going to be interesting. I'll leave it on the screen, but I want to take a copy of it in case I Manato lose it. So we'll just do it in sections. So that's one. Right? I'm just going to put that down here out the way and it shouldn't disappear. Oh, we've got another one, a writing one set a bit bit quicker. Write word equations for each of these reactions. Have you just moved it, just get that arrow on again, okay? Yeah, so this is the thermal decomposition. So decompose, we know that word, like worms and bugs that decompose leaves, breaks them down into their component parts. Right. Cutting that out, let me move down. All put that on the chat. The other chat finished. Okay, get rid of. Right, moving on. Right. Let's when we go back to that, right, representing the reactants and products. So we've done word equations done. Now we're going to go on to symbols and then we'll go on to balancing. So how do we write chemical formula? We write the symbol for the elements, uppercase for the first letter and lower for the second. If there is a second, if there is more than one atom by oxygen, we will write a number after the symbol to show how many atoms. And the number is in what we call subscript. So it's small and it's at the bottom. So some atoms are what we call diatomic. They are more stable if they are hanging around in pairs like oxygen. For example, magnesium mg oxygen O2, magnesium oxide MgO. And we've just got some diagrams here of the atoms. So what would the formula be for sodium to draw that? Just write it in that space. Just here, Linda, what would it be? Not two capitals. Really? Not it. Just do it with your pen. Just write it rather than do it. Yeah, you're going to need to anyway because you you're going to struggle to do your little numbers, right? That's good. What about nitrogen? Yeah and carbon dioxide. Got it correct, correct and correct. How many of each type of atom are present in water? H2O? Right. Sorry, that just gave you the answer for that one, two hydrogen and one oxygen. What about ammonia nh three? Perct. I supposed enjoy it. No, no. Just tell me don't bother writing that. You just tell me six carbon, twelve hydrogen, six oxygen. Yeah and there it is. A glucose molecule and that's a small molecule. Unlike starch, bill looks pretty big. Okay, so that's glucose. So that's one molecule of glucose. Symbol equations are another way of representing a reaction. Instead of using the names, we use symbols, obviously, because it is quicker and symbols are all represented in the periodic table. And it is a universal language, much like the symbols that we use in electricity. You want those symbols to be understood across the whole world. It's no good each country having their own symbols because that would not be universal. So instead of using the names, we use the symbols. For example, carbon reacts with oxygen to produce carbon dioxide. So what's the word equation? Just tell me. What was the word of pression? Carving plus. Oxygen is carbon dioxide. And how do we represent that using symbols yet? So you can do the symbols feel like it's kind of done at the bottom? Why does it randomly keep putting answers in? Bit confused about that, right? Yeah Urbon oxygen not equals. All right. Yep, thanks so much for doing the answer already. Formula for carbon is c, formula for oxygen is zero, two. Carbon dioxide is co two, so we can put them together. Pustraightforward so far. Now coming on to state symbols. What do we mean by state symbols? Like if it's like solid, liquid or gas? And then what's this last one? Eight queous eight queous right. Does that remind you of a word? Like aqua. Water water. So this literally means Yeah dissolved in water. So a solution where the solvent is water. So when we are writing a symbol equation, we should put the state symbols in. Solid gas, carbon dioxide. So we have carbon plus oxygen, carbon dioxide. Carbon is a solid. Oxygen is a gas. Carbon dioxide is a gas. That's a state symbols. Oh. Right? Correct answers gone. Pretend you didn't see it. Calcium carbonate caco three is a White solid. So what? You've clicked back. And again, one more. Yeah. So what elements does that contain? Cao three. So what is it? What's ca? Yeah. C is. Carbon oxygen and oxygen Yeah right solid good cathree solid plus. Carbon dioxide water. And it produces calcium hydrogen carbonate and it's told us it's a solution. So your symbol is going to be aq. Yep, got it right. And now the ants are at the bottom. Let's check. Correct correct correct. Yeah, brilliant. Right, let me just double check. I think now we're going to go back and we're going to add our symbols to those reactions. And they're all still there. So that's great. But I think it's going to be easiest to deal with my cutouts. Otherwise things might start moving. Right, let's. Cut out the symbols lower down. So let's put these at the top, start losing things whizzing around here, right? I've got that one. Now what I might get you to do, rather than cutting out, I might just get you to write it on, might be a little easier because otherwise I think it could get a bit crazy. So this is our second page, so we don't need any of the arrows or the pluses. So here's the symbols. So I'm going to get you to use these symbols and just write them underneath. So that's better, Linder, than trying to cut them. Yeah, Yeah, let's do that then. Okay, go on then, whenever you're ready. I'll let you move things around as you need to. Magnesium carbonate, magnesium oxide. That's a symbol for potassium. Yeah, that's it. You've done the periodic table, haven't you? But Yeah. Like not that much. Yeah symbol for lead is pb. Beam. Yeah water brilliant, right? A little bit more practice on symbol equations and then we'll go on to balancing. Yeah, okay. Probably best writing this rather than trying to type. So you've got to include state symbols for reactants and products. Yep. Good. Is that big enough? Okay. And then so five. So Yeah, and only done good practice. Yeah. Get around that room. Yeah, just close your bracket on the eight queous. All right, finish on this one, then. All right. Done. Okay, finish there. Popping that on the chapter so we can remember what you've been doing. Let's finish off that PowerPoint, and then we'll go on to balancing. And then I can give you the balancing worksheet for your homework. But you don't have to write it, you can just tell me to save a bit of chime. Tell me, so just word equations. Sodium plus chlorine. It's sodium chloride. Yeah chlorine chlorine. Carbon plus oxygen is carbon dioxide. Iron war plus oxygen is a solid compound, right? We wouldn't say iron wool wejust say iron, iron plus oxygen, iron oxide. Okay, right. Symbol, you can tell me the symbols. I Yeah don't worry about that to say solid Yeah solid plus. Gas is. Solid. Sao two solid so sai solid plus O2 gas arrow. Sao two solid. And ng c. Three. Solid, solid. Plus H2S O H two so four aq Yeah is. Mgs so four A Q plus H2O like l plus co 2G. Okay now mg so four aqueous Yeah soluble so eight queers for that one rather than the solid. M solid plus? C S C S O four. Aq Yep is. MgSO for aq plus. Good. Okay, let's go on to balancing equations. My, what do we want? We want. That one. And. That one. So balancing equations, coming back to our conservation of MaaS, we know that nothing can be created or destroyed. It just changes form. So you've got to have equilibrium in your equation. You've got to have the same number of atoms. So we've got the symbol equation for the reaction between carbon and oxygen. So carbon, solid oxygen gas, carbon dioxide gas. And here it is, carbon two oxygens, because they hang around in pairs. Co two molecule. When we count the number of atoms, we can see that it is balanced. So they've rearranged, but we haven't lost anything. We haven't gained anything. So our scales are balanced. Right now. We're looking at another one that isn't so we've got magnesium solid, one atom, oxygen gas, two atoms in our reactants. But something's gone wrong with our products. So what's gone wrong? There's missing like an oxygen Yeah now we're presuming this is in a closed system. We're presuming that nothing has been lost to the air, so this oxygen atom cannot have disappeared. So this is not balanced. So this is where we've got to start writing in our numbers to get it balanced. So let's look at this step by step. So we know the number of atoms of each type does not change. So what this actually means is that we make twice as much magnesium oxide. We show this in a symbol equation by putting a big number two in front of the molecule, magnesium oxide. And this is called a multiplier. When we now count the number of atoms of each type, we've now got another problem because we've got too much magnesium. Okay, so we put our multiplier in. So we doubled the molecules of magnesium oxide, which is great, sorted our oxygen problem, but now we've created a magnesium problem. So what would you do? Take away a magnesium? We can't start splitting up molecules. Divide by me, no. So it's magnesium that is our problem. So we've got to do something to the magnesium reactants. What can we do? Add magneto three. So we put a big two and multiply a number, double the magnesium. Yep, there we go. Okay, here you're going to balance because you should be balanced. Now why is that not balanced? Right? That is right. Let me go back. So we have added two magnesium atoms to the reactants. So the equation is now balanced, two magnesium atoms, two oxygen atoms. Right. So let's look at this one so you can write this in now. So write your reactants and your products for magnesium, hydrogen and chlorine. Okay, Linda Yep one Yeah p good one. Magnesium. After one hydrogen atom, one chlorine atom. Yeah. Yeah, Yeah. Okay. So what you're going to do from add two in front of hci? Okay. So then that would become. Two hydrogens, two chlorines that's looking good, that's looking balanced. 对言。There we go. Balanced. All right, let's do this one. Right. Can we put a little two over here like this? Can we do that? No, why not? Because you can't change the thing because that would be a completely different chemical that wouldn't be water anymore. So we can't add the small numbers. We've just got to add multipliers. All right? So it's the products that's a problem gone then that. So it's 42. Yeah. And then you need to more. So you put like a two here. Brilliant. Yegot, it yevery good. So that's all it is really. It's nothing particularly complicated. So she follow those rules. And there we are. Come on. Yewe've, got there. And then the next slide just goes on to say why we can't add a small two to the oxygen, because we would actually be creating here H2 hundred two is hydrogen peroxide, which is a completely different chemical. It is not water used as a cleaning fluid. All and we've got five minutes left. So let me show you your homework and then we can go through last week's homework. So I've got to decide whether I'm going to give you this one, which is a slightly easier worksheet, because you get the little table and you can go through and you can write in your numbers of atoms, and that gives you nine, or I can give you a hardoa, which doesn't have the table and you've got twelve. So which one would you like any? Do you think you're going to need the table to help you visualize what you need to do, or do you think you'll be all without it? I think I'll be all right. So I'll give you the harder one then. So I'll give you the one with twelve. All right. I shall pop that on for your homework. Let's have a little look and let's get. Some of this marked. A conservation of MaaS, explaining changes in MaaS. Did we do some of this in the class or we did a similar one? Didn't we wear a couple of the reactions were the same? Magnesium ribbon burnt in oxygen is chemical and the MaaS will increase. MaaS, Yep, is the oxygen that is added. And of course, we didn't actually measure how much oxygen because it wasn't in a closed system. Hydrochloric acid with powdered marble. And you get a gas. It's decreasing because the gas muscle is escaped gas, yet it's escaping into the atmosphere. Water, basalt, dissolved. Physical yethe same. Nothing new is formed. Brilliant, just because you can't see it. So what's happened is it's just gone. The salt molecules have just gone into the spaces between the water molecules. And that's why the solution becomes saturated when you keep adding the salt, because it can't go into those spaces anymore. So you start seeing it. Lemonade left open, physical decrease. It's going flat because the gas is escaping into the air. Zinc, so metal plus acid bung is on the top of the tube, we can see bubbles same. Yep, traps the gas. So we have what we call a closed system. Brilliant. Let's put that on. Click the next one. Right. Calculations should be quite quick to mark if you got it all right, which I'm sure you have. Yes. Well, that was quick. Perfect. Last one. Coppcarbonate is heated, reacts to form solid copper oxide and carbon dioxide gas. Student heated 1.24 grams of copper carbonate strongly after heating. Student measured the MaaS, the solid product as 0.8. Why did it decrease? Castle escape, sir. Yep. Sorry, I don't know why I can't write there. So this is what we call an open system rather than the other one, which was a closed system. Yep. So just a couple of new words for you. Open system and closed system. That's just a proper terminology. All right, Linda, we are done. So you're happy with your homework. I'll put that on the chat for you, and I will see you next week. Say bye bye.