Problem 12 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

An isomer of ethanol is : (a) methanol (b) diethyl ether (c) acetone (d) dimethyl ether

Step-by-Step Solution

Answer

Dimethyl ether is an isomer of ethanol.

Step 1: Understand what is an isomer

An isomer is a molecule with the same molecular formula as another molecule but with a different chemical structure. This means that the molecules have the same number of each type of atom, but the arrangement of these atoms in space is different.

Step 2: Write the molecular formula for ethanol

Ethanol has the molecular formula \( C_2H_6O \). This formula indicates that ethanol consists of 2 carbon atoms, 6 hydrogen atoms, and 1 oxygen atom.

Step 3: Compare the molecular formulas of the options

- Methanol has the formula \( CH_3OH \), which is \( CH_4O \). It does not match the molecular formula of ethanol.- Diethyl ether has the formula \( C_4H_{10}O \), not \( C_2H_6O \).- Acetone has the formula \( C_3H_6O \), which is not \( C_2H_6O \).- Dimethyl ether has the formula \( C_2H_6O \), which matches the formula of ethanol.

Step 4: Confirm the correct isomer

Since dimethyl ether and ethanol share the same molecular formula of \( C_2H_6O \) but have different structural arrangements, dimethyl ether is the isomer of ethanol.

Key Concepts

Ethanol Molecular Formula

Ethanol is a fascinating chemical compound often associated with alcoholic beverages, but its significance extends far beyond that. The molecular formula of ethanol is \( C_2H_6O \). This simple formula reveals that each ethanol molecule consists of two carbon atoms, six hydrogen atoms, and one oxygen atom. These atoms are arranged in a specific way to form ethanol's characteristic structure. Ethanol's structure involves a two-carbon chain (ethyl group) connected to a hydroxyl group (-OH). This particular arrangement is what gives ethanol its unique properties, such as its capacity to dissolve a wide range of substances and its important role as a solvent in chemical processes and laboratories. Understanding ethanol's molecular formula is the first step in acknowledging its complexity and versatility in both industrial and biological contexts. This formula lays the groundwork for learning about ethanol's interactions, reactions, and its pivotal role in organic chemistry.

Dimethyl Ether

Dimethyl ether is often encountered in discussions of isomers, especially in the context of ethanol. Like ethanol, dimethyl ether shares the molecular formula \( C_2H_6O \), but the way in which its atoms are arranged differs from ethanol. Instead of forming a chain with a hydroxyl group, as in ethanol, dimethyl ether's structure involves an oxygen atom sitting between two methyl groups \( (CH_3- O -CH_3) \). This structural difference significantly influences the properties of dimethyl ether. For instance, unlike ethanol, which is a liquid at room temperature, dimethyl ether is a gas.The unique arrangement of atoms in dimethyl ether makes it an ideal candidate for a variety of industrial applications, such as a propellant or a refrigerant. This serves as an excellent example of how simple changes in atom arrangement can lead to diverse chemical identities and functionalities.

Chemical Structure Analysis

Chemical structure analysis is the process of determining the arrangement of atoms within a molecule and understanding how this arrangement affects the molecule's properties and behavior. When comparing isomers like ethanol and dimethyl ether, structure analysis becomes critical because it reveals differences that are not apparent through molecular formulas alone.For instance, although both ethanol and dimethyl ether share the formula \( C_2H_6O \), their structures are palpably different, leading to distinct chemical properties and uses. Through chemical structure analysis, scientists can:

• Identify functional groups like the hydroxyl group in ethanol.
• Understand bonding patterns that contribute to a molecule's stability and reactivity.
• Predict how structural changes affect physical properties, such as boiling and melting points.

By exploring these aspects, chemists can better design and utilize molecules in both fundamental research and practical applications. In isomeric compounds, such detailed analysis is essential for drawing connections between structure and function, paving the way for innovations in chemistry and related fields.