There is a large difference in the boiling points of butanal and butan - 1 - ol due to

Options

A. intermolecular hydrogen bonding in butan -1-ol
B. intramolecular hydrogen bonding in butanal
C. higher molecular mass of butan-1-ol
D. resonance shown by butanal .

Answer

To understand the large difference in the boiling points of butanal and butan-1-ol, we need to analyze the structures and intermolecular forces present in both compounds.

### Step 1: Identify the Structures
- **Butanal** (an aldehyde) has the structure:
\[ \text{CH}_3\text{CH}_2\text{CH}_2\text{CHO} \]
- **Butan-1-ol** (an alcohol) has the structure:
\[ \text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{OH} \]

### Step 2: Analyze Intermolecular Forces
- **Butanal** primarily exhibits **dipole-dipole interactions** due to the polar carbonyl (C=O) group. However, it does not have the ability to form hydrogen bonds.
- **Butan-1-ol**, on the other hand, has a hydroxyl (-OH) group, which allows it to form **strong intermolecular hydrogen bonds**. This is because the hydrogen atom of the hydroxyl group can interact with the lone pair of electrons on the oxygen atom of another alcohol molecule.

### Step 3: Compare Boiling Points
- The boiling point of a substance is influenced by the strength of its intermolecular forces.
- Since butan-1-ol can form hydrogen bonds, it has significantly stronger intermolecular forces compared to butanal, which only has dipole-dipole interactions.

### Step 4: Conclusion
- The large difference in boiling points between butanal and butan-1-ol can be attributed to the presence of **intermolecular hydrogen bonding** in butan-1-ol, which leads to stronger attractive forces between molecules compared to the weaker dipole-dipole interactions in butanal.

### Final Answer
The large difference in the boiling points of butanal and butan-1-ol is due to the presence of intermolecular hydrogen bonding in butan-1-ol, which is absent in butanal.

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