 So let's do this problem. It says, identify the reaction types that each of these reactions are, and they could be more than one of the list of them. OK, so they're all balanced for us, so that's nice. You just have to remember, well, what do these things mean? So some of the easier ones may be combination and decomposition. So combination means if you've got one or two things, and they make one thing. So two or more, and they make one. So if we look here, we've got this one, where we've got potassium plus chlorine, and it goes to potassium chloride. So you see we have two starting materials, and it goes to one product. So that's definitely a combination reaction. So since we started with this one, well, it can be combination. Remember, combinations can be redox or non-redox. So this one is going to be more than one type of reaction. It's going to be a combination. It'll be a redox or a non-redox. So let's figure out what it is. Well, if you recall your oxidation number rules, this is zero here. And in a compound, they're not going to be zero. These ions, in particular, are regular ions. Potassium's always plus one, and chlorine's always minus one. So here, we see potassium changing from a zero oxidation state to a plus one oxidation state like that, and chlorine going from a zero to a minus one. So that's a change in oxidation state. So that means that it's a redox reaction. Does that make sense? But you said that potassium and chlorine, they're always zero. Well, in this case, because they're uncombined elements. Remember, that's the first rule of identifying what oxidation state your atom is at. So here, they're uncombined. So they're at an oxidation state of zero. But here, they're combined. So they're going to have their own oxidation state. Does that make sense? So let's look at some of these other reactions. So decomposition, well, that's one thing breaking into two things, or two or more things. And if I do a quick scan, well, see, here we have an aluminum trifluoride. And here, we have aluminum and three fluorines. So it's one thing breaking into two things. So that's a decomposition. Again, decomposition can be redox or non-redox. So this one, we're going to have to decide. Recall what we said about the last one. When we have an uncombined element, it's the oxidation number is zero. And if we have a combined element, its oxidation number is something other than zero, like in a compound. So if we look here, if we've got combined elements in a compound, and we look here, that guy's uncombined. That one's uncombined. So we went from, those guys are at zero. This is something other than zero. In fact, it's maybe to one and positive three. So you can see the oxidation number change. So this also is a redox reaction. Does that make sense? So let's keep going along with that oxidation number changing and uncombined, combined element thing, since we're getting good at it at this point. So hopefully, you see here in this next reaction, we have aluminum, which is uncombined here. So zero for aluminum. Over here, aluminum is in the form of aluminum oxide. So it's combined. So it went from zero to something else, right? So already, and iron here is zero over there, already we know this is a redox reaction. Does that make sense? Because aluminum went from zero to something else here. Remember, oxygen's always minus two. So three oxygens is going to be minus six. So aluminum here is going to be plus three. So it went from zero to plus three. Iron went from zero over there. So this is minus two, plus three, same thing. So you see it went from three to zero. So iron got reduced in that reaction. Remember, when the oxidation number goes down in value of its reduction. So if you want to think about it, aluminum got oxidized in that reaction. Because aluminum went up, yeah. The other thing is, if you get oxidized, you're the reducing agent. And if you get reduced, then you're the oxidizing agent. So it's kind of an opposite. I don't know, term knowledge. So since this is a redox reaction, but it's also something else, hopefully you can see, we've got the aluminum here stealing iron's partner. So aluminum stealing oxygen from iron. Do you see that? And like bumping iron out of the way, and iron has to go off by himself. Do you see that? That's called a single displacement reaction. Because one thing is displacing another thing, as opposed to a double displacement where two things are displacing each other. So this guy is switching partners with the iron. That's a single displacement. If we would have noticed that first, we would have all automatically been able to say it's a redox reaction. Why? Because single displacements are always redox reactions. So does that make sense? So let's continue along with, well, we know what a decomposition reaction is. So it's where we have one starting material and it breaks into more than one product. If we look at our remaining reactions, this one, this one, and this one, hopefully you see this is a decomposition reaction. Because we've got one thing breaking into one, two things. So this thing here, this decomposition. So let's just write that really quick. So decompositions we know can be redox or non-redox. So in this case, just like in the last one, we had to figure out what the redox numbers were. So here we've got combined. Here we've got combined. Here we've got combined. So we can't just say 0 on any of those things. So we're going to have to figure it out for everything. Remember, sodium is always plus 1. If you remember the carbonate, that's a polyatomic anion. If you didn't remember that before, hopefully you realize that it's supposed to be a minus 2 charge because there's two sodiums attached to it. So this is minus 2 for the carbonate all to get. So if you want to think about it that way, so CO3 2 minus, oxygen is always 2 or minus 2. There's three of them. And then carbon. So what's the oxidation number of carbon? So C plus minus 6, minus 2, C equals plus 4. So I'm putting, well, so that was for the whole thing, but oxygen is minus 2, carbon is plus 4. Is it OK that we did that? I'm going to erase all of this work here, just so it doesn't get in the way. OK, so those are our oxidation numbers. If those don't change, if any of those don't change over here, then it's a non-redox reaction. So remember, we said that oxygen for our class is always minus 2. So here, we've got a minus 2 oxygen. Since we've got two of them, minus 4, the whole thing is 0. So carbon must be plus 4. So carbon, we can already say, went from plus 4 to plus 4, so it did not change oxidation state. Does that make sense? It went from plus 4 here to plus 4 here. So no change. And oxygen, we said, is always minus 2 for our class. So that means that oxygen is a minus 2 as well. So that one's minus 2, that one's minus 2, and that one's minus 2. Did oxygen's oxidation number change? No. So now, all we've got to do is look at sodium, but what do we know about sodium? Always plus 1, right? Always plus 1. So did its oxidation number change? No. So this is a decomposition reaction that's also a non-redox reaction. So you've got these two decomp reactions that you want to compare to each other. OK, so does that make sense so far? We'll leave that. OK, so we've got two more reactions to do. Let's look at them individually. The top one, hopefully, you can see straight away that sodium is taking the place of hydrogen, and we've got sodium and chlorine paired up instead of hydrogen and chlorine paired up. And if you can kind of think about the structure of water, you can kind of think of it like HOH, like that, instead of how we write it shorthand, H2O. So if you look at it that way, hopefully, you can see that the OH and H have paired up. So they've switched partners. Does that make sense? Do you see that? So the OH is the polyatomic ion. If you didn't know that, it's called a hydroxide ion. That's something that you need to know. So OH is one entity, and it's paired up with H now, to make water. And sodium is paired up with chlorine. So we call this, since they switched partners, a double displacement. You can go about finding oxidation numbers, because it's going to make this video so long if we do all the oxidation numbers for both of these remaining two reactions. The one thing I'm going to tell you is that double displacement reactions are always non-redox. So I'm never reading them. So you should go, Carly, you should go home and prove it to yourself that this is a non-redox reaction. But we're just going to take the shortcut and say, non-redox, because it's double displacement. But double displacement reactions, that's where these two choices come into play. Acid base or precipitation. A lot of times these double displacements will be one of those two types of reactions. And if you remember what we said about acid base reactions, it's whenever an OH or something that has a lot of electrons takes an H away from something else. So you'll learn more about it in a few chapters. But for right now, since we're just introducing it, that's what you want to think about, when an H is removed from something by something else. In particular, an OH for this class, OH minus the hydroxide. So that is called an acid base reaction. So this one, you can classify with three terms. Acid bases are always double displacements. That's a way to think about acid bases. And when you have hydroxide and it's the thing removing the hydrogen, you're always going to be making the water. So that's another good way to kind of remember if it asks you what are the products or something like that. You know you're going to be making water. So that kind of helps you out. How much is this supposed to make CO2 and water? Always, yes, CO2 and water. I mean, for our class, pardon me. Both of them were just like one. No, both of them. Yeah, because what you're going to do in a combustion reaction, and unfortunately, we don't have one up here. That was when I was like, man, I wish we could squeeze one more in here with a combustion reaction. Combustion reactions, you always start off with something that has carbon in it. Of the H. C-H-O something. C something, H something, O something, you know? And that will go, and that doesn't necessarily have to have oxygen in it. But C something, H something. And that will always go to carbon to the outside of water because with combustion reactions, you're always reacting with oxygen. So that's where your oxygens are coming from in your carbon dioxide water. If you don't have oxygens to start out with in that carbon compound, or organic compound we call them. Okay, so since we just got done with this double displacement reaction, I kind of saved these. I did them in an order that I wanted to, okay? So if we look down here, hopefully, since we have experience with the double displacement reaction up here, hopefully you can see down here, this is also a double displacement reaction where lead is stealing iodide from sodium. Do you see that? And sodium is taking the nitrate from the lead. So here we've got sodium iodide and here we've got sodium nitrate. Here we've got lead two iodide. Here we've got lead two nitrate. So they kind of switched partners. Did like the docy-dough or something like that, okay? So that's always a double displacement. Whenever you see them switching partners. So my red hand is like, no, I can't get a displacement. What do we say about double displacement? They're always what? Non-redox, right? So that's something to make you remember. That's good. But is this an acid base reaction? Can you tell me that? So if I see somebody, no, it's not, right? Yeah, no, it's not. How do we know? Well, there's no hydrogens being transferred, right? So nothing's taking a hydrogen away from something else. In fact, what you hopefully see is that on this side we have an aqueous solution. On this side we have an aqueous solution, right? So two aqueous solutions. And what we're getting in the product side is a solid here. So that means something precipitated out. So this is a precipitation reaction. So I think we have one of those, two of those, one of those, two of those, none of those, but we talked about it. One of those, one of those. Remember, this is double displacement, this is double displacement, okay? Maybe we should write this. And redox, non-redox. Every one of them you wanna label whether it's a redox or non-redox, okay? Are there any questions? I know we went through a lot of stuff, but this is a good mini lecture on this stuff, so.