so let's start with reactions of alkanes and there's two major ones that we typically see one is combustion reactions and one is halogenation reactions so let's take a look at combustion reactions first let me just show you generally what the reaction is you can take any alkane so i'm not going to draw a specific one i'm just going to draw write the word alkane and so you can think of any alkane you want your head and it can go right there and if you add a little bit of oxygen what you get is a product is co2 in water of course this reaction is not balanced but this is the combustion reaction notice in a combustion reaction the o2 the oxygen the co2 the carbon dioxide in the h2o or water always is the same the only thing that changes is the alkane and this is something you've seen before this is what happens in your car engine if you burn some wood if you burn any alkane like at your at the at your furnace or on your stove if you have a gas stove that's an alkane that comes out and you burn it so this is basically burning stuff is what combustion reactions are so we're burning hydrocarbons remember alkanes are hydrocarbons which i'll just put hc for hydrocarbon so it's a hydrocarbon you have a little bit of oxygen if you ever want the hydrocarbon not to burn you know you can close it up in a container it doesn't get any oxygen and therefore will not burn and i'll show you a specific reaction in just a moment to give you an example a halogenation reaction of alkanes now let's recall what's a halogen a halogen is things like fluorine chlorine remember these are all diatomic molecules meaning there's two of them so it's f2 meaning there's two fluorines to make the molecule f does not exist by itself in nature it only exists as two of them together chlorine is the same as like bromine and iodine if you look on the periodic table they're all in the same column and so therefore they're very similar in reactivity and so those are halogens so halogenation is putting these on an alkane so again if i give you an example and i'll just use something very simple just to start but it could be any alkane if you have an alkane like methane ch4 so that's an alkane and we add a halogen and we can use any of them i'll just use fluorine as an example this reacts if you get a little bit of heat this reacts and one of the fluorines will switch spots with one of the one of the hydrogens on methane and so if we switch spots we'll get we'll remove one of the hydrogens that's ch3 and replace it with the fluorine so there's ch3f plus and we used to have two fluorines that would be in there as a reactant but now we're gonna have an h has replaced one of the f's and so now we have hf and if you give it enough fluorine into this reaction you get a lot of fluorine in the reaction all the hydrogens of on the carbon can be removed and replaced with fluorine so if you let this reaction continue and keep adding fluorine you'd eventually get to the point where you're ch or cf4 if you could just keep putting fluorines in place of hydrogens so why don't you give it a try here is a reaction um of these two of this of this reaction right here go ahead and determine and write down pause the video and write down what the products are and then come on back and we'll talk about it so in this video in this on in this reaction we can see that this molecule over here this big molecule right there that's an alkane and if we oxidize it by adding oxygen this is a combustion reaction so the products of this are simply co2 and water this is a combustion reaction and that's notice the products here are always going to be the same for a combustion reaction it doesn't matter what alkane you start with notice we have in the alkane carbons and hydrogens we have an oxygen out here and notice in our products we didn't lose any of those i still have carbons oxygens and hydrogens again this reaction is not balanced but nonetheless there are our products so it doesn't matter how big and complex the alkane is the products are always the same in a combustion reaction so now here's another reaction go ahead and pause the video determine what the products are once you think you've got them come on back and we'll chat about it so again the first thing you have to do is identify what reaction this is and this is a halogenation reaction notice we have an alkane our same alkane we had in the previous reaction so we have an alkane and then we have a halogen so this is going to be a halogenation reaction which means basically one of the chlorines is going to switch places with one of the hydrogens and we have a lot of hydrogens to choose from and so in this case you can pretty much choose any one you want and that's a potential product now some of the hydrogens are more likely to change spots with the chlorine but for our argument at this point let's just say all of them are possible and so therefore any of them is a possible reaction a possible product so in this in this case there's many possible products for instance what we do know is remember this cl2 if i just draw it a little bit differently is really this it's two chlorines bonded together by a covalent bond and we're going to take one of these chlorines and we're going to switch it with any of the hydrogens we want there and we're going to switch them so for instance i could remove this one and remove that one and we're going to switch spots so the chlorine will be there and the hydrogen will be there right that's one spot i could have also switched it not to there let's leave it there and i could have switched it to this spot right here that's possible or any of the spots and that would be and that's a product of this reaction now if we had a lot of chlorine in the reaction and i didn't say whether there was a lot of chlorine or just a little chlorine but if we just let the reaction go one time this is a possible product if we added more chlorine so if we added another molecule of chlorine right i would switch one of these chlorines with one of these hydrogens i'll pick this one right here so let's go ahead and move this hydrogen and move this chlorine so the hydrogen will come down here and form hcl and the chlorine will come up here and form that guy and we could continue to add chlorines until they are all completely full all the hydrogens were removed and all the chlor and replaced by all chlorines so there's a lot of different products here for sure but if the reaction just happens once and we have let me just go back to that if the reaction just happens once what are we getting there yeah and we get this and forget about we won't worry about that so if the reaction just happens once this is one possible product but realize this chlorine could be in several spots to make a slightly different molecule so there's more than one answer for this but there's definitely some incorrect answers but this would be one correct answer where you have two products you have the alkane with a chlorine on it and you have the no longer have a chlorine atom you have a hydrogen chloride the acid now with alkenes and alkynes we have four different reactions that can take place hydrogenation halogenation hydrohalogenation and hydration and a key thing to know about reactions of alkenes and alkynes remember alkenes have a carbon-carbon double bond and alkynes have a carbon-carbon triple bond it is there that all the reactions occur it occurs at the double carbon-carbon double bond or at the carbon-carbon triple bond it doesn't matter how big the molecules are focus on that carbon-carbon double and carbon-carbon triple bond that's where the changes are going to occur and with all these what we're going to be doing is you'll notice we're breaking the double and triple bond and we're adding atoms to it so we're going to take two things and combine them together to make one thing so it's an addition reaction like three plus four equals seven we took two things three plus four three and the four and we combine them together to make the seven in this case we're gonna be taking two molecules in each of these cases we're gonna be taking two molecules combining them together to make one molecule by combine while combining them we're breaking those double and triple bonds so let's take a look at the first one that's hydrogenation hydrogenation is hydrogen notice that's part of the word so we're dealing with hydrogen here again just like chlorine and bromine and so forth hydrogen exists in nature as h2 or h bound to h is another way to look at it and what these can do is we can take any alkene or alkyne we add the hydrogen to it and what we're going to get is an alkane or an alkene so by doing this the alkene will become an alkane the alkyne will lose one of the bonds it'll go from three bonds to two bonds and notice with the alkene we go from a carbon-carbon double bond to a carbon-carbon single bond we're going to break that one of those bonds in halogenation again we start with an alkene or an alkyne and i'm just abbreviating there it's the same as on the first one now halogenation we just learned just a moment ago all the halogens f2 cl2 br2 so we can take any halogen we want and just as an example i'll use br and what do we get there is we get a dibromo so two bromines on an alkane or dibromo two bromos on an alkene again the alkyne which is a carbon-carbon triple bond will be removed to and one of those bonds can be broken to make an alkene with the carbon-carbon double bond or we take a carbon-carbon double bond and we break one of those bonds to make a carbon-carbon single bond and the bromo groups are added to it hydrohalogenation notice hydro that's h and we know what halogens are and so these would be things like hbr or hcl or hi or hf any of those because it has a hydrogen and a halogen and it's the same we can take our alkenes and alkynes plus again i can use any of them but that's an example of one and so in this case i would get a chloro alkane so an l came with a chloroglu group on it or a chloro with an alkene depending on if i started with an alkyne or an alkene in a hydration reaction hydration we can recognize as water and again we can take our alkene or alkyne we can add a molecule of water and what we get here is an alk is an alcohol or we get an alkene with an alcohol group as well on it so it's sort of a mixture and i'll give you a couple examples of each of the an example of each of these so here's one so go ahead and give this one a try based on what we just talked about and see if you can come up with the product of this reaction when you think you have the product come on back and we'll chat about it so in this reaction we first take a look at what we have and notice we have a alkene right here right you can see it's an alkene because i see this carbon-carbon double bond right there so i know i have an alkene there's a lot of stuff hanging on it but nonetheless that's an alkene and then i'm adding hydrogen to it so this is a hydrogenation reaction because i'm adding hydrogen to it and remember this is an addition reaction so we're going to take this alkene and add on the hydrogens and i told you when you do this focus on that carbon-carbon multiple bond that carbon-carbon double bond in this case we're going to focus everything right here now because we're adding things to it we're not going to subtract anything so the things currently hanging on the carbon those those two carbons involved in the double bond meaning this methyl group that will still be there when we're done this will still be there when we're done because remember we're adding we're not subtracting this will be there when we're done and all of this will be there when we're done so really we can just kind of in our heads just kind of remove that from our brain for a moment at least mentally and we're going to just focus on that carbon-carbon double bond that we did not square up there now i'm going to remove the squares just to clean this up a little bit but just mentally so i'm going to focus just on that carbon-carbon double bond and what happens is that we're going to add it so let's take these hydrogens now remember this hydrogen is really that and we're going to float it on over to here just so we get a little get it a little bit closer so i'm going to put them right here so we're going to line it up and all we're going to do is we're going to break that carbon-carbon double bond and we're going to break this hydrogen hydrogen bond so i'm going to move this bond to here move this bond to here essentially and we're going to create new bonds let me go ahead and erase the old bonds and let's put the new bonds in and the color here doesn't matter i just happen to have a purple pen on me that's what it is so now you can see the new hydrogens have added on and we now have a carbon-carbon single bond where we used to have a carbon-carbon double bond and so here now we have an alkane so we've made an alkane in this process what's the other product well there is no other product we added all of that one we added all of this to the alkene to form the alkane and so that's our product so we have an alkane as a product and the two new hydrogens are added on so let's try this one here's another one so go ahead and uh determine what the product of this reaction is so go ahead and pause the video then come on back when you're ready and we'll chat about it so in this one again i see i have an alkene shown in red here the same one we had in the previous reaction but this time we don't have a hydrogen molecule we have a hydrohalogen so this is a hydrohalogenation reaction but you'll see it's pretty much the same as the hydrogenation reaction with the hydrogen atom again let's just focus on where the reaction is going to occur and the reaction is going to occur right around that carbon-carbon double bond so let's go ahead and take this hydrohalogen and we're going to move it on over to here so we're going to remove it from there we're just going to slide it on over here to get it close to where it wants to go and then we're going to go ahead and start breaking some bonds we know we're going to break the carbon-carbon double bond at least one of them and make it a single bond so we'll move this bond to here and we'll move the bond between the hydrogen and the chloride over to here to form two new bonds and let me go ahead and erase what is now gone and notice here again now what we have formed is the product so it's a single molecule as the product notice we took the alkene we took the hydro hydrogen halide and we just combined them together to form one molecule so there's only one product and we bound we now have an alkane as our product and the alkane does have a chloride on it now it doesn't matter which way i put the hydrogen and the chloride on i could have done it the way i did it here or let me erase a few things here and let's say instead of attacking like this i put the hydrogen here in the chloride over here that would move the chloride to a different carbon so it makes a different product so although we add two things together to make one molecule we could have made a couple of different molecules either the chloride on this carbon whoops either the chloride on this carbon or the chloride on this carbon either way we still made an alkane with one chlorine atom on it so here's another one to try you can go ahead and give this one a try determine what the product is and then come on back and we can chat about it so again we see that we have an alkene here with a carbon-carbon double bond and so we know that we're probably going to be going after that carbon-carbon double bond that's where we're going to attack and that's where the reaction is going to occur it doesn't really matter what else is on notice that in all these reactions we don't really care what else is on the carbon carbon attached to the carbons of the carbon-carbon double bond we those don't get changed in any way here we have a fluorine fluoride ion and i'm sorry fluoride and we have we can redraw it like that where it's two floorings connected by a covalent bond and we're gonna move that guy right on over to here and we're gonna have the reaction go and in this case again we're gonna move the carbon one of the carbon-carbon double bonds on down the bond connected to two fluorines over here so we make we move those two so let me now remove what is now gone after moving those electrons to a different spot and we get that guy and again since the two fluorines are the same it doesn't really matter which way they connect to the carbons there's always going to be one fluorine on one and one fluorine on the other carbon and so there's one product in this reaction again we've added two things together to make one thing and so that's our product notice that it was an alkene it lost a double bond to it went to a single bond and so now it becomes an alkane with two fluorines on it or two halogens on the molecule okay we'll do one more go ahead and determine what the product of this reaction is let's put the arrow over here determine what the product this is when you think you've determined what the product is come on back and we'll chat about it so in this one now this is a little bit different this time now we don't have an alkene we have an alkyne knows the carbon-carbon triple bond in there but it doesn't change our strategy at all it's a little bit different it looks a little bit different but keep the method of what you're doing the same we're also going to be adding a molecule of water so this is a hydration reaction because we're adding water water is hydration and so we're going to change this molecule this water molecule to make it look ready to add on to our alkyne so again we're going to be adding it on water likes to break apart notice there's not two atoms here but three atoms but it likes to break apart between the oxygen and one of the hydrogens to form a hydrogen and a hydroxyl group and so we're going to go ahead and move that on over to here so we'll put a hydrogen here bond it to a hydroxyl group here but at this point again at we just do it the same way we've been doing it doesn't matter that it's an o h or an f or whatever this is what we're just going to work with and we're going to do the same thing as we've done before we're going to move one of the bonds of the triple bonds so not two of them just one of them we're going to move it on down to here as we've done before and we'll move the bond connecting the hydrogen and the oxygen on up to here to go there let me go and erase what is now gone after we make the remove those electrons and that is what we get we get that molecule right there notice this is got a carbon-carbon double bond so it looks kind of like an alkene but it also has an oh group so it also has a an alcohol look to it so it's basically an alcohol and an alkene now we could have put that hydrogen we could have put that on in the opposite direction meaning i could have not ended up with a hydroxyl group on the one carbon but put it on the other carbon so we could have basically had this look let me get my three bonds back there's my three bonds and just as before because the two atoms that are connecting to the carbons of the triple and double bond are different there's two different ways in which it could go on but still the same thing happens we move one bond down to here one bond up to here to form these two bonds and let's get rid of what has now been moved because of that reaction and we get that notice in this case this is also a possible product but notice in this case the oh group is now on a different carbon than it was previously now if there was enough water around because now we have an alkene it could undergo the reaction again and so we could actually have another molecule of water i don't know how much space i have but let's take another molecule of water and in a second reaction because there's an alkene still there oop i'm having trouble getting that there we go uh it's not wanting to do it i don't know why but you can see that those two lines there that's supposed to be an h it's just not wanting to connect for some reason oh there we go and one of the bonds will move to here one of the bonds will move to here so we'll connect those let's erase what's in between or what was lost in that reaction and we get that and that bond should be connected to the oxygen not the hydrogen and so we get that and again that one could have gone on either way so the oh group could have ended up on the carbon it's showing it's ended up on or could it ended up on this carbon so it could have gone either way so in the end because this reaction happened twice we could have the ohs on the same carbon or different carbons it both are possible and both are correct in terms of being able to form so both will form they just might not form in the right the same amounts but nonetheless both will form so this is a hydration reaction in this reaction i showed you what it looks like with a triple bond and a double bond because we did both so if you started with a double bond the same thing would happen we'd add a molecule of water and make an alkane with a hydroxyl group on it which is essentially an alcohol