Draw the following three isomers of C 5 H 12 as condensed structures: c.

Welcome back, everyone. Let's take a look at our next problem. It says, consider the isomers of butane shown below and we have straight chain butane and then I so butane with three carbons in the main chain and one branch says provide their condensed structures with choices A through B different condensed structures being offered. So let's look at our structures and expanded structures and decide what the proper conen structure would look like. So we recall to make these condensed structures, we eliminate the carbon bonds and just write the number of hydrogens next to each carbon with branches listed in parentheses. So our butane straight four carbon chain with, of course, the terminal carbons having three hydrogens and the internal ones having two. So we see in choice A butane is listed as CH three ch, two, ch, two, ch three. That's correct when we look at Choice B. However, it's listing the second carbon as having a branch, A CH branch, which wouldn't exist anyway, because a branch there would have to have three hydrogens. So Choice B is not correct. Let's look at choice C. Well, choice C is listed all as a straight chain as it should be, but it has 12345 carbons. So it has too many carbons in the butane structure. So choice C is incorrect. And then in choice D, the butane structure is written correctly with those four carbons. CH three on either end. Now, we need to look at the iso butane structure and that will help us choose between choices A and D. So is Soutine has three carbons in the chain, there's a methyl branch. So it should be CH three in parentheses on the middle carbon. And note that of course, that middle carbon will only have one hydrogen since it, it has another bond to a carbon. So let's look at choice A, we have ach three for our first carbon. But then it shows this methyl branch being on the first carbon instead of the middle carbon. So choice A is incorrect when we look at choice D. However, it shows CH three ch with our methyl branch of parentheses, CH three and then the terminal CH three. So choice D represents the condensed structures of butane and iso butane correctly butane straight chain, four carbons iso butane main chain with three and a methyl branch on the middle carbon. So choice D is our correct answer here. See you in the next video.

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12. Introduction to Organic Chemistry

Condensed Formula

GOB Chemistry

12. Introduction to Organic Chemistry

Condensed Formula

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Problem 5c

Textbook Question

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

Verified step by step guidance

Step 1: Understand the problem. The molecular formula C₅H₁₂ corresponds to an alkane, which is a hydrocarbon with only single bonds. Isomers are compounds with the same molecular formula but different structural arrangements. For C₅H₁₂, we need to draw three different structural isomers.

Step 2: Start with the simplest structure, the straight-chain alkane (n-pentane). Arrange all five carbon atoms in a single continuous chain and add the appropriate number of hydrogen atoms to each carbon to satisfy the octet rule (each carbon should form four bonds). Write this as a condensed structure.

Step 3: Create the first branched isomer (isopentane). Rearrange the carbon atoms so that there is a main chain of four carbons with one methyl group (-CH₃) branching off the second carbon. Again, add the appropriate number of hydrogen atoms to each carbon and write the condensed structure.

Step 4: Create the second branched isomer (neopentane). Rearrange the carbon atoms so that there is a central carbon atom bonded to four other carbon atoms (a quaternary carbon). Add the appropriate number of hydrogen atoms to each carbon and write the condensed structure.

Step 5: Verify that all three structures have the molecular formula C₅H₁₂ and that they are unique. Ensure that each carbon has four bonds and that the structures are distinct from one another. Label each isomer appropriately (n-pentane, isopentane, neopentane).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Isomers

Isomers are compounds that have the same molecular formula but different structural arrangements of atoms. This can lead to variations in physical and chemical properties. In the case of C₅H₁₂, there are several structural isomers, including straight-chain and branched forms, which must be accurately represented in condensed structural formulas.

Condensed Structures

Condensed structures are a way of representing the molecular structure of a compound in a simplified format. They show the connectivity of atoms without depicting all the bonds explicitly. For example, in C₅H₁₂, a condensed structure might look like CH₃(CH₂)₃CH₃ for n-pentane, indicating the arrangement of carbon and hydrogen atoms.

C₅H₁₂ Molecular Formula

The molecular formula C₅H₁₂ indicates that the compound contains five carbon atoms and twelve hydrogen atoms. This formula is characteristic of alkanes, which are saturated hydrocarbons. Understanding the implications of this formula is crucial for identifying the possible isomers and their respective structures.

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