Which of the following pairs of structures are identical, which are isomers, and which are unrelated?
a.

Question

Which of the following pairs of structures are identical, which are isomers, and which are unrelated?

a. Chemical structures labeled as CH3CH2CH3 and CH3 with a vertical bond to CH2CH3, questioning their relationship.

Accepted Answer

Hi, welcome everyone. Let's take a look at this. Next problem. Identify the relationship between the following pairs of structures as identical isomers or unrelated. We have two pairs of structures labeled one and two. So our choices are a one isomers, two, not related B one identical two isomers, C one identical, two identical or D one isomers, two isomers. So let's look at our pairs of structures. First, we want to make sure that they're related that they have the same molecular structure. If they have a different molecular structure, they'll be unrelated. So we look at our pair number one and see that they each have 12345 carbon on the 1st, 12345 carbon on the second. So we've got C five. Now let's look at the number of nitrogens. These are only have hydrogen and nitrogen. Oh excuse me, hydrogen and carbon. So on the first structure, we have 1 to 3 carbons that have three hydrogens each. So that's a nine, then two is 11 and one more is 12. So we have H 12. On the second structure, we have 123 carbons with three hydrogens each. So nine and then 1112. So they do have the same uh molecular structure. So they're either identical or isomers. So look at, let's look at which one it is. So for number one, I'm going to draw a line structure. I think it's a little easier to see the connectivity that way. So we have a main chain of four carbons. So we'll draw that 1234 and it has a methyl group on carbon two. So put that there. And then the second one in the pair has another chain of four carbons and a methyl group on carbon three. Well, when we look at these two molecules, it's pretty clear to see that all we have to do is rotate our first structure 180 degrees and it will be identical to structure number two. So these two molecules are identical. So we can rule out choice A which says isomers for number one and rule out choice D which says isomers for number one. Now let's look at our second pair of structures. Again, let's check our molecular formula. We have 12345 carbons in the 1st and 12345 carbons in the second. So we have C five in terms of our hydrogens. And the first, we have 1234 carbons with three hydrogens each. So that's 12 and one hydrogen on our nitrogen. So 13 carbons and one nitrogen. Let's check our second structure, we have 12345 carbons, we have 1234 hydrogen, four carbons with three hydrogens each making 12 and then 1/13 hydrogen and then one nitrogen. So not related is not an option here or either isomers are identical recline that isomers have the same molecular structure but different connectivity. So let's draw our line structures here. For the first molecule, we have a carbon connected to a nitrogen, then two more carbons. So 12 with two methyl groups on that carbon next to the nitrogen. So put two methyl groups there and then our second structure has carbon connected to nitrogen. Then a methyl group coming off the nitrogen, then it's attached to two more carbons. And the final carbon also is a methyl group. So you can see right away that they're not identical we have in the first nitrogen bonded to two carbons and a hydrogen. And the second structure, our nitrogen is bonded to three carbons. So since they have the same like formula but different connectivity, the pair in number two are isomers. So we want to choose choice B which is one identical two isomers and eliminate choice C which says one and two both have identical pairs. So once again, the relationship between these pairs of structures is choice B. Number one, an identical pair, number two isomers. See you in the next video

Which of the following pairs of structures are identical, which are isomers, and which are unrelated?
a.

Verified video answer for a similar problem:

Key Concepts

Identical Structures

Isomers

Unrelated Structures

Which of the following pairs of structures are identical, which are isomers, and which are unrelated?a.

Verified video answer for a similar problem:

Key Concepts

Identical Structures

Isomers

Unrelated Structures

Which of the following pairs of structures are identical, which are isomers, and which are unrelated?
a.