Question

Which among the following has highest boiling point?

• A. Butyric acid
• B. Valeric acid
• C. Acetic acid
• D. Formic acid

Hint:

Within any homologous series (alkanes, alcohols, acids), boiling point ALWAYS increases as the molar mass (number of carbons) increases! Branching lowers it, but here they are all straight chains.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
For a homologous series like carboxylic acids, the boiling point increases with an increase in molecular mass and surface area.

Step 2: Formula Application:
1. Formic acid ($C_1$) 2. Acetic acid ($C_2$) 3. Butyric acid ($C_4$) 4. Valeric acid ($C_5$)

Step 3: Explanation:
Valeric acid (pentanoic acid) has the longest carbon chain among the given options. As the chain length increases, the magnitude of van der Waals forces increases, requiring more energy to boil the liquid.

Step 4: Final Answer:
Valeric acid has the highest boiling point.