Which of the hydrocarbons in each of the following groups are isomers?
Hey everyone, so in this question is our job to figure out, which one of these two or which one of these are isomers of each other. Remember just what isomers are, they're going to be different compounds with the same molecular formula, okay? So we're going to go through all these and figure out what is their molecular formula and then we're actually going to go ahead and name them. So, in the first one recognize that this is what? what's the name of this compound? Well, it has four carbons, so we know this is going to be a butane. Now, it's just a regular alkane, so if we have four carbons, we actually can predict the number of hydrogen's, we have, right? So, our formula should be C4H10, right? Because the general form that we use for that for regular alkane is CnH2n plus 2, alright? So, let's go ahead and move on to the next one try and do exactly what we did for the first one, so what's the name for this? Well, it's four carbons, it's not butane, right? it's cyclobutane, this is our cyclobutane, so we have four carbons again 1, 2, 3 and 4, so we should expect that we have four carbons but here we have a ring, so that's going to decrease our number of hydrogens by two, it's going to be C4H8, the general formula for that would be CnH2n, right? Now, this could also have had a double bond as well and still have that same formula but our butane and cyclobutane are isomers of each other? No, because one has the molecular formula C4H10 the other one is C4H8, okay? So they're not isomers, let's move on to the last two. Now, for these to notice that, particularly the last one, here we have 1, 2, 3, 4 carbons, right? But in total, we have four carbons 3 chain, we actually have five carbons in this total structure, what this is going to be is this is going to be a two methyl, what? 2-methylbutane, right? So, 2-methylbutane, we have C5H12, it still follows this formula CnH2n plus 2 because it's an alkane but these are, if we compare our butane, our cyclobutane and our 2-methylbutane none of these are isomers of each other, so let's actually look at that last one we have left, here how many carbons do we have? we have four carbons. Now, do we have any double bonds and rings here? no, so we know they should follow the formula of CnH2n plus 2. So, how many hydrogens should just have? it should have ten just like our butane, okay? So, which one of these two pairs are isomers of each other? they're going to be different compounds of the same formula, we're going to say that this structure right here and this source right here are isomers, our butane and we didn't name this compound so let's go ahead and name it, what do you think the name is going to be? we have our carbon one, our carbon 2, our carbon 3, this carbon four is going to be named as a substituent, so this is going to be a 2 methyl and our longest red chain is three carbons, so we know it's going to be propane, okay? So, believe it or not, our 2 methyl propane and our butane are actually isomers of each other, okay? So hopefully that makes sense and use your weight to rule one of these. Now, when we would notice that our 2-methylbutane have five carbons, so that one definitely couldn't be an isomer of our regular butane. Alright guys? Well, hopefully this makes sense and let me know if you have any questions on what we did.