Question

An isomer of ethanol is (a) Methanol (b) Diethyl ether (c) Acetone (d) Dimethyl ether

Short answer

An isomer of ethanol is dimethyl ether (d).

Step-by-step solution

Understand Isomers

Isomers are molecules with the same molecular formula but different structural arrangements. Ethanol has the molecular formula \( C_2H_6O \). Our task is to find another molecule with the same formula but a different structure.

Compare Options with Ethanol's Molecular Formula

First, identify the molecular formula of each option:- Methanol: \( CH_4O \)- Diethyl ether: \( C_4H_{10}O \)- Acetone: \( C_3H_6O \)- Dimethyl ether: \( C_2H_6O \)

Select the Correct Isomer

Look for the option that shares the same molecular formula as ethanol:- Dimethyl ether: \( C_2H_6O \)Dimethyl ether has the same molecular formula as ethanol, hence it is an isomer of ethanol.

Key concepts

Ethanol

Ethanol, a well-known alcohol, is commonly found in alcoholic beverages and is also used as a solvent and in chemical synthesis. Its molecular formula is \( C_2H_6O \), which means it contains two carbon atoms, six hydrogen atoms, and one oxygen atom. The structure of ethanol is like a two-piece carbon chain linked to an alcohol group (\(-OH\)). This structure is what gives ethanol its characteristic properties.
One of the intriguing aspects of organic chemistry is how different arrangements of the same set of atoms can lead to distinct molecules called isomers. Isomers share the molecular formula but differ in the arrangement of atoms, influencing their physical and chemical properties. In ethanol, the \(-OH\) group is attached to the end of the carbon chain, which fundamentally alters its characteristics compared to other isomers with the same molecular formula. Understanding the structure and behavior of ethanol is crucial for students learning about alcohols in organic chemistry.

• Ethanol is flammable and can be used as a fuel.
• It is also used in the production of hand sanitizers and medicinal drugs.
• The boiling point of ethanol is about 78.37°C, a key property that varies significantly from its isomers.

Dimethyl ether

Dimethyl ether is a simple ether with the same molecular formula as ethanol, \( C_2H_6O \), yet it has a different structural configuration. Instead of an \(-OH\) group, dimethyl ether features an oxygen atom bonded between two methyl groups \((CH_3) \). The presence of this ether linkage gives dimethyl ether its unique properties.
This structural difference highlights the concept of structural isomers in organic chemistry: despite having identical molecular formulas, substances can have vastly different physical and chemical characteristics based on their structures.

• Dimethyl ether is a colorless gas at room temperature, whereas ethanol is a liquid.
• It has applications as a propellant in aerosol cans and as a potential fuel source.
• Due to the absence of the \(-OH\) group, dimethyl ether cannot participate in hydrogen bonding like ethanol, affecting its boiling and melting points.

Molecular formula

The molecular formula of a compound states the number and types of atoms in a molecule but does not offer information on their arrangement. It serves as a bridge to understand the basic composition of organic molecules.
For ethanol and dimethyl ether, their shared molecular formula \( C_2H_6O \) illustrates the concept of isomers. Isomers have the same constituent atoms but differ structurally, leading to varied properties.

• A molecular formula like \( C_2H_6O \) cannot reveal whether a compound is an alcohol like ethanol or an ether like dimethyl ether.
• Structural formulas or models are required to see the connectivity of atoms, which dictates the compound's characteristics.
• Understanding molecular formulas is essential for grasping the concept of isomerism, a core principle in organic chemistry.

Discovering how the same atoms can rearrange into different structures provides insight into molecular diversity and complexity in organic chemistry, emphasizing its relevance in real-world applications and scientific research.