Draw the following three isomers of C₅H₁₂

Question

Draw the following three isomers of C₅H₁₂ as condensed structures:

a.

Accepted Answer

Welcome back, everybody. Our next problem says, the isomers of hexane are shown below and we have Hexane, two methyl pentane and three metal paintings with their structures drawn out with all the bonds and the carbons and hydrogens all depicted directly on there. Then it says, what are their condensed structures? And we have four different answer choices a through D with different condensed structures. So we'll go through each of those as we look at our structures and think about what the condensed structures would look like. The four condense structures, we eliminate the bonds. So we don't have any bonds drawn and we just draw right in the carbons as groups of units. So for a methane group, ch three, we put branches and indicate them by parentheses, branches indicated by parentheses if a branch has multiple groups, for instance, it's an alkane chain, it has a subscript telling us how many units are within that branch. So with that in mind, let's look at our structures and think about what their condensed version would look like. So our Hexane has no branches whatsoever. It's just a straight six carbon chain with the maximum amount of hydrogens on each. So we would expect ac six carbons with the right number of hydrogens. So let's look at choice A for Hexane. It has indeed ch three, ch two, ch two, ch two, ch two, ch three, so six carbons with CH three S on either end. And CH two S in the middle straight chain, no branches. So let's look at our other answer. Choices to see if they're correct as well. Choice B for Hexane has a group in parentheses. So it says C and then in parentheses, ch 32. Well, that would be a two carbon chain on carbon one. So this is definitely incorrect as a condensed structures that would indicate a branching or a chain. And we don't have that in Hexane, we look at choice C, it is correct as well. Got our six carbons and with the correct number of hydrogens. And then in choice D also correct condensed structure for Hexane. So we need to move on to our next molecule. This is two methyl pentane. So we have a methyl group here on carbon number two to highlight that in blue to point that out. So we do have a branch. We have our main chain high like Daniello. It's now a Penta because our sixth carbon is in a branch that will be indicated separately. Our main backbone there is only five carbons. So let's look at our structures and see which one would be correct. Well, our first carbon here will just be CH three. Then we'll have a CH there's only one hydrogen on our carbon two and in parentheses, CH three to indicate that messy branch. So let's look at choice A, we have CH three chch three. So this part is correct, it indicates the correct position of the branch and size of the branch. Do we have the correct total numbers of carbon one, 2345 in our main chain with one in the branch? So choice A has a correct name or correct condensed structure? Excuse me for two methyl pentane B, we've already eliminated. Let's look at choice C choice C we have the correct indicator the age. However, we do not have the correct first carbon here because it has ach first, but we know a terminal carbon will always be CH three. So our structure needs to start with CH three. Then we would have CH for carbon two and then our branch CH three. So choice C definitely not correct. Now, let's look at choice D twisty says R two, methyl pentane, CH three. That's correct. Ch Yep accidentally wrote that in red. So CH three CH, there's our branch that's 12 and then three more carbons making up the main chain with one methyl branch. So choice D also has the correct condensed structure for the second molecule. Now let's look at our third molecule three methyl pentane. So in this case, our branch is on carbon three. So 123. So there's the methyl group and here's the carbon it is bound to or mean Jan 12345 Carmens. That's where the pentane comes from. So we've just got to decide between choice A and choice D So let's look at the name or excuse me, the content structure 43 methylate and choice A. Well, we have our first two carbons, ch three, ch two. That's correct. Carbon three is indicated as ch it's only got one hydrogen. Then our branch which is a methyl branch is on there correctly and then there are two more carbons. So the condensed structure for three methyl pentane and choice A is correct. So I'll go ahead and select that since we know we don't have more than one correct answer. But to be thorough, just look at choice D. Choice D shows the first Carmen as being Ch which wouldn't be possible, would have to be CH three and then shows a methyl group on the first carbon. But that again is not going to be the location our methyl group should be on carbon three. So methyl group on carbon three. So once again, our proper con structure is shown in choice A aane with its six carbons in a row two methyl pentane with its branch indicated on carbon two and three methyl pentane with its branch indicated on carbon three. See you in the next video

Draw the following three isomers of C₅H₁₂ as condensed structures:
a.

Key Concepts

Isomers

Condensed Structures

Structural Representation

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