Question

There are two different substances with the formula \(\mathrm{C}_{4} \mathrm{H}_{10}\). Draw both, and tell how they differ.

Short answer

They differ in their structure: n-butane is linear, while isobutane is branched.

Step-by-step solution

Identify the formula

Both substances have the chemical formula \(\mathrm{C}_{4}\mathrm{H}_{10}\), which indicates they are isomers, meaning they have the same molecular formula but different structures.

Draw the first isomer - n-butane

The first isomer is n-butane, which is a straight-chain alkane. Its structure is: \[ \mathrm{CH_3-CH_2-CH_2-CH_3} \] This structure has no branches and all carbon atoms are connected in a linear fashion.

Draw the second isomer - isobutane

The second isomer is isobutane, which is a branched-chain alkane. Its structure is: \[ \mathrm{CH_3-CH(CH_3)-CH_3} \] This structure has a central carbon atom bonded to three other carbons, forming a branching point.

Compare the structures

n-butane is a straight chain with all four carbon atoms in a row, whereas isobutane has a branched structure with one central carbon atom bonded to three other carbons, making it a more compact shape.

Key concepts

n-butane

n-Butane is a simple organic compound that belongs to the alkane family. It's made up of four carbon atoms in a straight chain. This chain-like structure is known for its lack of branches. You can visualize it as a line of carbon atoms connected one after the other, specifically structured as \( \mathrm{CH_3-CH_2-CH_2-CH_3} \). Because of this linear framework, n-butane is often referred to as a "normal" or "straight-chain" butane. This structure is quite compact linearly, allowing it to easily fit and connect with other molecules.
Among its uses, n-butane is found in household gas supplies, lighters, and in some industrial processes. Its main characteristic is that the absence of branches makes it much different in shape and physical properties compared to its structural isomer, isobutane. This difference in structure leads to variations in boiling points and physical states under certain temperatures, which is a crucial aspect when comparing structural isomers.

isobutane

Isobutane, like n-butane, falls under the alkane classification but exhibits a distinct branching in its structure. It is also known chemically as methylpropane. The structure of isobutane is slightly different from n-butane, as it includes a central carbon atom that connects to three other carbon atoms, forming a "branched" shape. This can be written structurally as \( \mathrm{CH_3-CH(CH_3)-CH_3} \).
This branching gives isobutane unique properties compared to n-butane:

• It has a lower boiling point.
• The compact nature of its branched structure means it occupies less space than the linear chain of n-butane.

In everyday life, isobutane is often used in refrigeration systems as a refrigerant and also in the petrochemical industry. Its compact shape allows it to mix and react differently with other substances compared to the linear n-butane. These differences in physical properties highlight why understanding structural isomers is crucial.

structural isomers

Structural isomers are fascinating for their distinctiveness while sharing the same molecular formula. Two molecules can have exactly the same number and types of atoms, yet structure them differently. This idea is like how a set of building blocks can form different shapes. With n-butane and isobutane both having the formula \( \mathrm{C_4H_{10}} \), their structures diverge, demonstrating the concept of structural isomerism.
Key points about structural isomers include:

• They have identical molecular formulas but different connectivity of atoms.
• The distinct structures lead to varied chemical and physical properties, such as boiling and melting points.
• They reside as crucial concepts in organic chemistry to explain how different chemical behaviors arise from the same base composition.

Recognizing these differences aids in areas like pharmaceuticals, where distinct isomers can yield drastically differing effects. It’s a foundational concept that emphasizes how structure plays a pivotal role in the functionality and interaction of molecules in various applications.