Question

The number of isomeric alkyl halides possible for \(\mathrm{C}_{5} \mathrm{H}_{11} \mathrm{Cl}\) is (a) 5 (b) 6 (c) 4 (d) 8

Short answer

The number of isomeric alkyl halides for C_5H_{11}Cl is 8.

Step-by-step solution

Understanding the Problem

We're asked to find the number of isomeric alkyl halides, specifically chlorinated alkanes ( C_5H_{11}Cl ), from a given molecular formula. An isomer is a compound with the same chemical formula but a different structure.

Identify the Carbon Skeletons

First, we need to identify the different possible carbon skeletons for C_5H_{12} . For a 5-carbon alkane, there are three main structural variations: a straight chain (pentane), a branching with one side chain (isopentane or 2-methylbutane), and a branching with two symmetric chains (neopentane or 2,2-dimethylpropane).

Determine Possible Chlorination Sites on Pentane

First, consider normal pentane. The chloro group can be attached to any of the 5 carbon atoms, but because of symmetry, the attachments on carbons 2 and 3 are identical, as are those on carbons 1 and 5. This gives us three unique isomers: 1-chloropentane, 2-chloropentane, and 3-chloropentane.

Examine Isopentane Isomers

For 2-methylbutane, chlorination at the four unique positions (1, 2, 3, and 4) is possible due to its asymmetry. This leads to four isomers: 1-chloro-2-methylbutane, 2-chloro-2-methylbutane, 3-chloro-2-methylbutane, and 4-chloro-2-methylbutane.

Consider Neopentane

Neopentane (2,2-dimethylpropane) is highly symmetrical. There is only one unique carbon position for chlorination, resulting in just one isomer: 1-chloro-2,2-dimethylpropane.

Summing Up the Isomers

Add up all the unique isomers from each carbon skeleton type. Normal pentane contributes 3, isopentane 4, and neopentane 1. Thus, the total number of isomeric alkyl halides is 3 + 4 + 1 = 8.

Key concepts

Isomerism

Isomerism is a fascinating concept in chemistry that explains how molecules with the same molecular formula can exist in different structural forms. These variations are known as isomers. Even though they share the same chemical formula, their atoms are linked in different ways, leading to unique properties. This concept significantly expands the diversity of organic compounds. There are several types of isomerism, including structural (or constitutional) isomerism and stereoisomerism. Structural isomers differ in the connectivity of atoms, whereas stereoisomers differ in the spatial arrangement of atoms. Exploring isomers helps chemists understand how changes in structure can affect the properties and functions of molecules.

Chemical Structure

The chemical structure of a molecule describes the arrangement of atoms and the chemical bonds that hold them together. For example, when examining the alkyl halides with the formula \(C_5H_{11}Cl\), it's crucial to understand the various structural possibilities of the carbon backbone. Alkanes can form different structures based on how their carbon atoms are connected.

Consider a five-carbon alkane, which can be arranged in various ways such as a linear pentane, a singly-branched isopentane, or a doubly-branched neopentane. Each of these structures provides unique sites for a chlorine atom to attach, resulting in different isomeric forms of chlorinated alkanes. Understanding these structural differences is key in predicting and verifying the physical and chemical properties of the resulting compounds.

Chlorinated Alkanes

Chlorinated alkanes are a class of compounds formed when hydrogen atoms in an alkane are replaced by chlorine atoms. This substitution alters the alkane's properties, making the chlorinated alkanes more reactive and sometimes more stable. For the compound \(C_5H_{11}Cl\), chlorine can attach to various carbon atoms, leading to a variety of isomers.

The position of the chlorine atom affects the molecule's polarity, boiling point, and other physical properties. By exploring the attachment options, as seen in pentane, isopentane, and neopentane, chemists can determine the number of possible isomers. This information is crucial for applications in industries where specific chlorinated compounds are needed for manufacturing or synthesis processes.

Molecular Formula C5H11Cl

The molecular formula \(C_5H_{11}Cl\) represents a group of compounds known as isomeric alkyl halides. With five carbon atoms, eleven hydrogen atoms, and one chlorine atom, it provides various structural possibilities. Each arrangement leads to a different compound with unique characteristics.

Finding the number of isomers involves considering the number of ways in which the chlorine atom can be distributed among different carbon structures. From straightforward schemes like normal pentane to more complex ones like isopentane and neopentane, each arrangement defines a unique way to bond the atoms. Consequently, the total number of isomers for this formula stands at eight, illustrating the rich diversity available even within a single molecular formula. Knowing how to determine these isomers is a critical skill in organic chemistry.