 Okay, guys, let's start this lecture again, if you don't mind. So recall the last thing, so you guys don't mind me doing this, right? Okay, so we're just pretending, okay? So recall the last thing we talked about last time was when we have a chemical equation, okay, and it's got moles of gas in that chemical equation, we can actually use Le Chatelier's principle to drive the reaction to one direction or the other, okay? So pressure changes can occur in three ways. As you can imagine, you can change the concentration of the gas at inert gas or change the volume of the reaction vessel. The two things we're going to be looking at is changing the volume and changing the concentration of the gas. We've already talked about changing the concentration of the gas, and if we change it where it'll push the equilibrium mixture, we're now going to be specifically talking about changing the volume of the reaction vessel, which will, in turn, change the pressure of the reaction vessel, okay? So what you find is that if you change the volume of the reaction vessel, this causes a major change in the equilibrium position. So when the pressure increases, so if you can imagine, so if we've got our reaction vessel here, and we've got a piston, right? So if that, we push that piston down, that means the pressure is increasing, right? So the pressure is increasing in that respect. Also, the volume would be decreasing, right? So whenever the pressure increases, the volume decreases, okay? So it's the same but opposite if we're going to take that piston and instead move it up, right? That's going to give us a decrease in the pressure or an increase in the volume, as you would imagine, okay? So what you find is that when the pressure increases or the volume decreases, the system decreases the moles in the chemical reaction of gas, okay? So let's look at a general chemical reaction, maybe A gas plus B gas goes back and forth to C gas, okay? Like that. This would be a general reaction equation. So if we see, we've got how many moles of gas on the left side or in the reactant side? Two moles, right? And how many moles of gas do we have on the product side? One mole. So overall, we've got a two to one ratio of products to reactant moles of gas, right? That's what we're looking at specifically as moles of gas. Okay, so what is this saying? It says when the pressure increases, the system wants to decrease the moles of gas, okay? So we can either go from left to right or from right to left, right? So which side, the left or the right side has the more moles of gas? The left side, this has more, right? And of course, this is going to have less, right? So what does this say? When we increase the pressure, it decreases the moles on the system, right? So if we increase the pressure, which way is this reaction going to be pushed, to the right or to the left? If we increase the pressure, increase the pressure to the right, right? Because we are decreasing the number of moles of gas, right? If we decrease the volume, which way is this reaction going to be pushed? Decrease the volume. It's the same thing as increasing the pressure, right? We have that written here. So don't just say things, you know, we've got it all written here, okay? So look at the problem, analyze it before you say, okay? So let's try this one again. What happens if we decrease the volume? Which way is it going to go? So if we decrease the volume, does that want to have more moles of gas or less moles of gas? If we decrease the volume, less moles. So which way is it going to go? To the right or to the left? To the right, okay? So if we decrease the volume. If we increase the pressure, does that want to have less moles or more moles of gas? Less moles, why is that? Because we're decreasing the volume, right? So it's going to go to the right again, okay? So what if we decrease the pressure? What is that saying? We're increasing the volume, right? So does that give more or less room for gas particles to occupy? More room, right? So if we're going to increase the volume in this particular reaction, which way is it going to be pushed? To the left, okay? Why? Because it's more that way, right? So if we do this stuff, increase the volume or decrease the pressure, it's going to move it to the left. Okay? This is Le Chatelier's principle dealing with volume or pressure change, okay? So let's try a real reaction. I'll leave all this stuff up. And we'll do CaCO3 solid back and forth to CaO solid plus CO2 gas. Okay, so if this is our reaction, how many moles of gas? Remember we're only concerned about moles of gas, right? How many moles of gas do we have on the left side of the reaction? Yeah, zero, right? How do you know that? Because it says S here that tells us, right? Left, this one. That's all right. Okay, so we have overall zero moles of gas, right? What about overall on the right side of that reaction? How many moles of gas do we have? One, one, because this is the only one that says G, right? Okay, so remember now you might want to put more or less, you know, just to get your guys in the right frame set, right? Frame the mind. So is this more or less than this? Less, okay? So I'll just put less there. And is this more or less than this? More, okay? So this will help you. Okay, so if I erase these guys, okay? So if I decrease the pressure, which way is that going to push this reaction? Decrease the pressure. What does that mean? More volume. Increase the volume. So will the number of moles of gas increase or decrease then? Increase, why do you think that it'd increase? Because you've got more space to put them, right? That's all this is, all this is. Okay, so if we increase the volume, which way is this reaction going to be pushed, to the right or to the left? Increase the volume to the right, right? What if we decrease the pressure? Which way would this be pushed? To the left or to the right? To the right as well, right? Because decreasing pressure is the same thing as increasing volume, right? That's right, right? If I come over here and squish you down, right? You get smaller, right? So I'm putting a lot of pressure on you, right? If I come over here and stretch you out, right? You get bigger, okay? Well, I don't know if that's less pressure or not. But you can imagine, okay? Okay, so decrease, pressure, right? Increase volume, right? What if I decrease the volume? Would you want more moles of gas if you decrease the volume? No way, why? Because there's not enough space to put them. So in this particular reaction, if we decrease the volume, is it going to go to the side with more or side with less? Less, so it's going to go to the left, okay? It's all there is to it, yeah, it's all there is to it. The one thing I want you to know, though, let's look at these other problems. Let's just write the equation for B here. So we got S solid plus, what does it say? 3F2. Gas goes back and forth to S, F6, right? Okay, so how many moles of gas do we have on the right side of this equation? One, one mole, right? How many moles of gas do we have on the left side? Three, three, okay? So even though it only has one thing that's gaseous, right? It's got a coefficient that says three, so we say three times that is three, okay? So that one has a three to one ratio. Look at C, that's a two to two ratio, right? So when you got a two to two ratio, increasing the pressure, decreasing the volume is not going to do anything. It's not going to do any change, okay? So these three problems are really good for you guys to try out, and I've got the answers there for you, okay? And then you can try some more without the answers on your own, okay? I'm sure these would be very good problems because I could only imagine that I'll be talking about this on the test. Okay, so let's talk about, let's finish up chapter 8, talking about Le Chatelier's principle but in relation to temperature. So can I erase this stuff here? That was a better lecture than before anyways, huh? Too bad evaluations are already passed, huh? Then you could say how great I am for doing this again. Okay, so let's talk about this reaction that's presented here. Remember, I guess to preface this, remember when we have a reaction here, A going to B, and we got the change of enthalpy of the reaction being negative energy units, kilojoules per mole, is that an exothermic or an endothermic reaction? Exothermic, what does that mean that it's an exothermic reaction? What do you, what, it's giving off heat, so you're feeling it give off heat, okay? Yeah, so like, this is like your heater or something like that, this is an exothermic reaction, okay? So let's write this reaction here. A to B, A going to B says delta H equals negative 111 kilojoules per mole, okay? So that's your exothermic reaction, uh-huh. We could also look at the opposite reaction, B going to A. What we find is that when we measure the energy of B going to A is going to be exactly opposite of this but with the same magnitude, okay? So the delta H of the reaction going the other way is plus 111 kilojoules per mole. So this is an endothermic, there you go, yeah. This is exactly that, you know? Except that I think usually is talking about physics and somebody, when Mike Tyson punches you in the face you can think that your face punched his fist, you know, it's just as hard, it's non-spontaneous, yep, very good. So this reaction would prefer to go this way, right? Prefer to go this way. So I've put these two reactions together, right? We could break these up into their different processes, right, A going to B, B going to A like that instead of writing them like this, okay? Okay, so what are we actually saying? Remember we said an exothermic reaction does what? Gives off heat, okay? So if we were to refer to heat as part of the reaction, would we call it a product of an exothermic reaction or a reactant in an exothermic reaction, do you think? It's a product, right? Why is that? Because the reaction produces heat, right? Does that make sense? Okay, so whenever you see it having a negative delta H here you can think of it as saying A goes to B plus heat, okay? So like heat is a product, okay? So if we're doing this endothermic reaction what happens to the endothermic reaction? It absorbs heat, absorbs heat, that's a good way of thinking about it, it absorbs heat, okay? So what does that mean? Is heat a product of this reaction? It's a reactant, right? It actually needs heat to go, okay? It needs heat to go because it absorbs it, yeah, exactly. Okay, exactly what the reactant was, right? Okay, so this, remember delta H here was negative, delta H here positive, right? Okay, so now let's go back all the way back to what was it? Monday I think when we were talking about putting in excess reactant or excess product, right? Okay, so this, I'm gonna erase all of this delta H stuff here, okay? So this is the breaking up of these two reactions. Let's put them together, right? Where would heat be on this reaction? This side or this side? On the left or on the right? This one, here. Oh, you got this one and this one. Where is it? Where's heat? Wait a second, come on. What do you mean? What do I mean? So wait, okay, wait, wait, wait. Okay, wait, just one second. Is it the case that these two reactions combined is this reaction here? Is that the case? Okay, then if that's the case, we should be able to put this word heat somewhere, right? That doesn't make any sense. You can't have something that's- One place or another. Where, on the reactant side or on the product side? Where do you put it? Well, which side, okay? Where is heat? Where is heat? What, okay, what do you say? Beep? With the B, yeah, right? Because look, we got B plus heat there and B plus heat there. So don't be silly about things. Don't be just be like, I don't know, you know, I'm gonna put them instead of a reaction arrow. It's already given. Well, not necessarily, I mean, in this case, it's in the product, but it doesn't necessarily go on a product, you know? You gotta break it up into these reactions first, okay? But you get that from these numbers here, okay? It's not like that. No, it's not like that because they're the same reaction, you know? They're just going opposite directions. It's like this, right? I'm running forward this way, right? And this way I'm running backwards, right? So if I say, which way do you put the backwards running? You know, you don't say in the middle, right? You say with the one where you're running backwards. You know what I'm saying? Yeah, exactly. Or the opposite size shoes or something like, something weird. You know what I'm saying? Okay, so because it says heat plus B here and heat plus B here, right? It only goes to, it only makes sense to put the heat on the side where the B is, okay? Okay, so, right? Anyways, the other thing we knew is that this reaction was exothermic. So we should have realized that the forward reaction here is exothermic since we had that written down earlier anyways, right? Okay, so again, if you remember from our conversation on Monday, we talked about if you add more reactant or add more product to the reaction, which way it would push the equilibrium, okay? So if our reaction is A, okay, I'm gonna erase these two side, or these two individual reactions, okay? So if our reaction is A goes back and forth to B plus heat and I add heat to this, if I add heat to this, getting more of this, right? Which way is the reaction gonna go to the left or to the right? If I add more heat? If I add heat to the left, right? Because it goes like that, right? So if I add heat, I'm just gonna put add delta H like that, okay? To the left, right? What if I remove heat? If I remove it, so if I take this away, wait a second, come on now. What does Le Chatelier's principle do when you remove one of the products? It's gonna go to the right. Why is it gonna go to the right? What happens when you remove the product? Why does it go to the right? How about that? Do you remember what Le Chat, what does Le Chatelier's principle even mean? How about that? Let's start there. What does it mean? So I'm not gonna go on until somebody tells me what it means. Okay, so that's what Le Chatelier's principle says. So if I'm removing a product, what is it going to do? Make more products, right? That's what it does. It, if I remove it, it's gotta make more. It's like the factory, you know? So like if I've got a full warehouse of products, the factory's not gonna make any more product because they don't have anywhere to put it. But if the delivery man comes, grabs it all, right? Then the factory wants to produce more, right? Okay, what did we say heat was in this reaction? A product, thank you, a product, okay? So if we remove it, do we want, we're gonna wanna make more of it, right? So if we remove it, which way is this reaction gonna go? To the right. You should have known that anyways because it's gonna be opposite of what happens when you add it, okay? Okay? So, remember exothermic reactions give off heat? That means that heats the product of these exothermic reactions. Endothermic reactions absorb heat. That means heats are reactant for endothermic reactions, right? So if I increase the temperature for an endothermic reaction, it's going to make more products, okay? If I decrease, or if I increase the temperature for an exothermic reaction, it's going to push it the other way, go towards the reactants, okay? And that's essentially what this slide says, okay? When the temperature of a reaction is increased, an endothermic reaction will shift towards the products. The exothermic reaction will shift towards the reactants. If the temperature is decreased, the endothermic reaction will shift towards the reactants. The exothermic will shift towards the products. Okay, it's on the blackboard right now, so. We can check it after class and make sure, okay? It's the same thing that's written on the previous slide just in more words, okay? Catalysts, we talked about catalysts earlier. They can't change the position of equilibrium, but they speed up both the forward and the reverse reaction, okay? So don't worry too much about it. We talked about catalysts, kind of put this within the, within the slides that we were talking about catalysts, kind of just put this as another point for catalysts in your head, okay? So let's look at these, these reactions here, this diagram that I've given you. So this first reaction, since it's negative, that means that heat is a what? Product, right? So if we increase the temperature, does that mean we're adding heat or removing heat? Adding heat. So if heat's a product and we increase it, which way is this reaction gonna go? To the left or to the right? To the left, very good. To the left, why is that? Because we're putting more product in, so it gotta go this way, right? For half, you know, the thing is, is half of the people, when they first start talking about Le Chatelier's principle, get it wrong, the other half, get it right. After a second, when, because everybody's like, oh, that's backwards to me, you know? But once you realize the way it goes, then you just turn it around, you know? Okay, so I'll let you try those ones, the rest of them on your own, those are the answers to them, and here's some more that you can try on your own. Here's one that's a big word problem, something like this might be on the test. I'd go and try it, okay? That's the, well, go and look on the blackboard and you can see if they're there, okay? That's the end of chapter eight. Okay, so let's get chapter nine up here. Move on, moving on up. 93, that's it. Okay, so the thing is, normally people's lecture slides are like 20 or something like that, right? I mean, I don't know, I remember when I interviewed for this job, like they wanted me to do a 20 minute presentation, right? And I sent them my lecture slides for it, it was like 57 slides or something like that, and they were like, I can't believe that you got through 57 slides. I don't even think it was 20 minutes, I think it was like 15 minutes or something like that. But I just, you know, I mean, the way I do it is just like, and it really works well with I think a lot of slides, you know? Anyway, except there's a lot of printing to do, right? And I always look at my slides before every class and be like, oh, it'd be nice to put one more here, you know? And then everybody's like, wait, wait, wait, wait, it's not there, that's live, you know? Okay, so acids, bases, and salts, let's start chapter nine. So let's qualitatively look at acids and bases. Of course, acids and bases have been known throughout history for as long as people have been tasting sour and bitter things or slipping on, you know, slippery surfaces or things like that, okay? So as you can imagine, acids and bases have certain characteristics that are associated with them. Acids have a sour taste associated with them. So if you ever taste anything sour, it's probably acidic, like lemon juice, okay? They react with active metals like aluminum and zinc to produce hydrogen gas, okay? It's a good way to produce hydrogen gas is to put HCl on these reactive metals. And then they turn some organic compounds. These organic compounds we call indicators. They turn them different colors. So you've been exposed to this in the laboratory sessions when we've been doing the acid-base chemistry in the buffer reactions. You saw, or the iodine clock reaction, you saw the change in color due to an indicator being attacked by something. The iodine clock reaction isn't an acid-base indicator reaction, but those other ones were. So you've seen like phenylphthalein turn from clear to pink or bromocrysal green turn from blue to green, okay? Those are just indicators. In fact, here is a picture of hydrangeas. If you guys know about these flowers hydrangeas, they have an indicator in them, okay? And what you'll find is that hydrangea plants that are grown in what we say acidic soil, their flowers will be blue. And if you're grown in basic soil, your flowers will be pink. And it's because of the exact same compound. It's just got more OHs on it or more H pluses on it. We'll talk about that stuff later. Okay, so acids will do those things. What will bases do? Well, they taste bitter. They are very slippery. Okay, and they turn the same indicators different colors. So if anybody's familiar with soap, okay? Soap is slippery, right? So you can be fairly confident that it's a base, okay? Tastes bitter, right? If you've ever tasted soap, yeah, from when you were a little kid, right? I tasted it many times, too. I never got caught. That's the most, that's the best, right? So if you ever taste anything bitter or slippery, I feel it as slippery. It's more than likely basic, okay? So, and we'll talk about this later, but a neutralization reaction occurs when acids and bases react. There's some common household acids. You can see acetic acid. This is vinegar, citric acid is like lemon juice. Phosphoric acid is what you find in coke and soft drinks. Hydrochloric acid, you'll have to know if it's an acid. Hydrochloric acid, that's like pool cleaner. Sodium hydroxide is lye, ammonia, and then some other bases, okay? And you can see here some common acids with them using the pH paper as an indicator. You can see there, all the pH papers there are red or orange in this case. That means that it's acidic, okay? Then we look here, you see all that common household bases. You look at the pH paper, they're all blue. That means it's basic. Okay, so that was a qualitative look at acids and bases. Let's look at, well, still qualitative, but a little more in detail. Okay, so an acid is what? Well, it's a substance that produces hydrogen ions or H plus ions or protons, okay? So they all mean the same thing. Hydrogen ions, H plus ions, protons when dissolved into water. So you see this substance here, nitric acid is an acid, HNO3 is an acid. Why is that? Because HNO3 aqueous, remember if it says aqueous, that means it's dissolved into water, right? So HNO3 aqueous when nitric acid is dissolved into water, you see what happens. The reaction produces protons plus nitrate anions, right? It said, or the definition said, if a substance produces protons, then it's an acid, right? So nitric acid is an acid. You should know that, I guess, by the name, if nothing else, right? But yeah, so if you didn't know the name of this thing and you saw the reaction equation, you should know that because you see this proton in the products. A base is the opposite of an acid. It produces the other part of water. So if you think water is HOH, like that, right? This is the part the acid produces. This is the part the base produces. In fact, it's H plus and OH minus is what they produce. Okay, so a base, like we said, it's opposite. It's a substance that produces OH minus or hydroxide ions when dissolved into water. So potassium hydroxide is a base. Why? Because when we dissolve it into water, it goes to potassium ions and hydroxide ions. So what's an acid base reaction that's any reaction involving an acid and a base? And a neutralization reaction is any acid base reaction that forms both water and a salt. Okay, so recall what I was talking about earlier this morning before we started recording about salts, right? So I know that we're very familiar with salt, right? The term salt everybody uses for the stuff that we put on our popcorn or whatever, NACL, right? Okay, this is salt, right? That's its common name, but it's just A salt, okay? So anything really that's an ionic compound, okay? We call those salts, okay? So not only sodium chloride, but potassium chloride is a salt, right? Sodium iodide is a salt, but also sodium phosphate or silver chloride, silver one chloride or aluminum bromide. They're all salts, okay? So look here, when we look at this neutralization reaction here, we see sodium hydroxide, well we know that's a base because it produces hydroxide ions when it's dissolved into water. Hydroiotic acid, well we know that's an acid, again, not only from its name, but if we had broken it up into its half reaction, we would see that it dissolves into water and produces H plus ions or protons. But if we combine those base and acid together, you see we form water, right? And sodium iodide, sodium iodide is a salt, okay? Here you can see, here we've got a table of strong and weak acids and strong and weak bases. What you find is that something is known as a strong acid if it completely dissociates into water, okay? So if you've got something like, so we're just gonna make up an acid, right? HA, we'll say that's an acid because it's got that proton on it that is removable. So if it completely dissociates, what does that mean? It's when the reaction is over, this is all we've got. So that's a strong acid, okay? A weak acid, on the other hand, would be one that, what do you think? Does not completely dissociate. So how would we represent that in relation to something that completely dissociates? What do you think we're going to do? Are you telling me? How do we know? What's happening? What is this reaction look like at the beginning of the reaction? How much of this is in there? Relative to this and this? At the very beginning, time zero, time zero. How much of this is in the reaction? So percentage wise, tell me, 100%, right? 100% of this, right? Does everybody agree with me? At time zero, 100%. So we'll say HA, 100% like that. How much of this is present? H plus at time zero, at time zero. So if there's 100% of this, how can there be 100% of this? Wait, okay, so, okay, wait a second. Okay, so if I have A plus B plus C, right? A plus B plus C, three things. Okay, all of them together, what percentage is that? 100%, okay, that's 100%, right? So if, how can I explain this? Thank you, right? It can only be, if you've got 100% of this in, so if you've only got this in solution, right? Does that mean that you have this too? No, no. Uh-uh. Do you understand? Yes? Okay, if I say I only have this, that doesn't mean I have something else too, right? And 100%, that means I only have this, you know, that's what that means. Okay, so let's start again, okay? Time zero. So don't just guess, you know? Make logical answers, okay? How much of this stuff do I have in solution at time zero? 100%. Okay, if that's the case, how much of this should I have at time zero? Zero percent, right? So H plus is zero percent, right? How much A minus should I have? Zero percent as well, okay? Now at time end of the reaction, what does the reaction look like? So what do I have in the reaction? How much of this stuff do I have in there? At time end. Okay, what does this mean? Wait, what does this mean? What does this mean? This arrow means? It means what? This to this, okay? Okay, so if this has gone to this, how can I have 100% of that stuff? How can I have 50% of it? No, when I say strong acid, look at the strong acid, okay? That's what we're talking about, okay? So if I have this, it goes to this, how much of this do I have? Zero percent, okay? What did we talk about? What did we say this is doing? What does the strong acid do in water? What does it do? Completely dissociates, okay? So if it, what does it mean dissociate? What is that word? Completely breaks apart. It completely breaks apart. If it completely broke apart, how much of the combined thing do I have? Zero, okay? I need you guys to think logically, okay? So, HA, zero percent. Okay, now how much of this do I have in solution? 50%, right? This here, 50%, right? Because the combined of these two should equal to what? 100%, okay? So this is what it looks like. Does that make sense now? Okay, so this is what I want you to think about, okay? Okay, so time zero, time zero. At time zero we're looking, okay? So this is time equals zero. This is time equals end of the reaction, okay? At time zero, what does the weak acid look like? Time zero now, okay? 100%, why? That's all you do, at time zero all you got is enough to put that in there, right? So HA is going to be 100%. How much H plus? Why? Can't already have 100%, okay? A minus? Zero, why? There's nothing left, right? No, nothing left, right? Okay, so this might be a little more difficult, but okay, yeah, it should be something like that. It's not gonna be 33.3. In fact, these will be equal, and this will be some other number, you know? So this will be like this, this. Oh, you don't know because you don't know the K. If you knew K, then you could tell this, okay? But this is gonna be H plus, A minus, and this is gonna be something. This could be bigger or less, I don't know, you know? Again, if you had K, I could tell you. If K, if K was big, then these would be bigger than this. If K was small, then this would be bigger than these, okay? That's all right, we're gonna finish really quick. Okay, so the other thing we need to talk about is what's really happening in solution because this is not what's really happening in solution. This is a good way to think about it, but not what's really going on because this thing here, H plus is very, very tiny, okay? It's just a proton. Protons don't like to be by themselves. They like to be associated with negative charges, okay? So let's erase all this stuff. Can I erase this stuff? Everybody understands and has got this stuff? Okay, good. So what did we say when we go from like H, C, L, H, C, L, gas to H, C, L, aqueous, what's happened between there and there? What have we done? It got dissolved into water, okay? It got dissolved into water, that's what we've done. Okay, so what is this actually showing? When we dissolve this stuff into water, does it stay like this? Uh-uh, because this is a strong acid. We don't know our strong acids yet, but strong acids do what in water? Completely dissociate, right? So we say it goes like this, right? Like that, okay? But what did I just say? This doesn't actually happen, okay? So what actually happens, let's draw what we call a reaction mechanism for this. So let's draw our water molecule and let's draw our acid, H, C, L, okay? Remember, go-go gadget, right? Okay, so the electrons here are going to, because this thing is what? Partially positively charged, right? If we looked at the difference in electronegativity, we would find that's partially positive, that's partially negative, that's partially negative, that's partially positive, right? So these electrons will go and remove that proton there, making those electrons go to that chlorine. What we'll find is that we won't have just the H plus, but we have what's called the hydronium ion, which is H3O plus, plus CL minus, like that, okay? So that's what happens when it goes into water. Why is that? Because this thing is too tiny on its own to have that full positive charge, okay? It just doesn't like to have that, so yeah. So the oxygen takes that plus charge from that hydrogen, okay? It's like, I'm bigger, I'll take it and I'm kind of negatively charged. I like that stuff, okay? Okay, so that H3O plus ion, we call the hydronium ion. Okay? So here you see the same sort of thing that we just showed here, except here we showed the reaction mechanism, here it's just the chemical equation. And this one, notice, is weak acid. How can I tell that this is a weak acid and not a strong acid? It's going back and forth, right? If I was a strong acid, it would have a straight arrow to the right, right? Okay, so the last thing I want to do today is recall molecular equations, our total ionic equations and net ionic equations, and we don't have much time. I think I'm already running over time. So can I erase this stuff, guys? So you got this? Yeah, I know, but let's just go over it just so we can start next lecture at the right spot. Because I do have online students, you know? So just because we get something in class doesn't mean they always get it, you know? No. Ha, ha, ha, ha. Okay, so let's try to build the molecular total and net ionic equations of the reaction between HCl and aluminum hydroxide. Okay, so which one's the acid, which one's the base? Start there. Yeah, and why does everybody look at me like a deer in headlights when I say acid and base after we've talked about, an acid has what on it? A base, it has what on it? What is a base gonna do? Don't just say what she says, because she's not always right. They all dissolve in water, okay? Why, how do we know that this is an acid? What are you gonna say, how do we know this is a base? Does this, am I showing anything reacting with metals here? Am I showing anything, anything like that? Uh-uh, you should know why this is an acid, bam, bam, bam. Why is this an acid? Thank you, it's got a hydrogen here, right? Why is this a base? Here. Because it's got the OH, okay? It's got the OH, the H, right? Okay, so remember we talked about splitting up water, right? Acid portion, base portion. Okay, okay, so how many pieces, if you will, of water does this acid have in it? How many H's does this acid have, okay? How many pieces of the acid part of water, right? Does this have, that's what I'm talking about, okay? So how many H's does that acid have? One. One, and how many hydroxides does the base have? Three. Three, okay? So if I have three of these hydroxides, how many H's do I need to react with those three hydroxides? Three. Three, right? Does this thing have three H's? So what do I have to do? Add three, what? Times it by three, thank you. Make three of these things, right? That's what you wanna say. So we got like that, okay? So now, let's draw the molecular equation. I want all of you guys to do it on your own, okay? We don't have time, guys. They're gonna be coming in in like a second. So, so molecular equation. And don't just look at what we did earlier. Okay, so that's the molecular total. So now we gotta do the total. Did you write that? You already got that molecular down? Okay, keep going, write the total down. Okay, is that what you got? And then the net ionic equation. How do we get the net? We cancel our spectators. Three CL's on this side, three CL's on this side, cancel, cancel. AL three plus there, AL three plus there, cancel, cancel. So the net is going to be, okay, so now in a chemical equation, when the coefficients are the same, the ratio of the coefficients are the same, we don't keep them as this big number, right? We'll cancel them all out, yeah, exactly. So just like three to three to three is the same as one to one to one. So this is the net ionic equation. Okay, the last thing I wanna know is, how did I know this AL CL three was this physical state aqueous? Where did I get that from? Yeah, you just guessed. Why is that aqueous? Why did we not put solid or liquid? Why didn't we put aqueous here? We didn't have a liquid. Oh, that's not as anything to do with anything. Because it's soluble in water. We need to remember our solubility rules, okay? If this was lead sulfate or something like that, this would be a solid, right? And this would have put the in your net ionic equation. So you gotta watch that stuff, okay? If it's gonna be something like that, it'd be a solid. But since it's aluminum chloride, we know that's soluble in water. Okay, so it'll be aqueous. Let's stop there and say good luck.