o-nitrophenol is more volatile than p-nitrophenol it is due to

Options

A. Intermolecular hydrogen bonding in o- nitrophenol
B. Intramolecular hydrogen bonding in o- nitrophenol
C. Intramolecular hydrogen bonding in p-nitrophenol
D. More resonating structure of p-nitrophenol

Answer

To determine why o-nitrophenol is more volatile than p-nitrophenol, we need to analyze the types of hydrogen bonding present in both compounds.

### Step-by-Step Solution:

1. **Understanding the Structures**:
- **Ortho-nitrophenol** (o-nitrophenol) has the nitro group (-NO2) and hydroxyl group (-OH) located on adjacent carbon atoms of the benzene ring.
- **Para-nitrophenol** (p-nitrophenol) has the nitro group and hydroxyl group located on opposite sides of the benzene ring.

**Hint**: Draw the structures of both o-nitrophenol and p-nitrophenol to visualize the positions of the functional groups.

2. **Identifying Hydrogen Bonding**:
- In **o-nitrophenol**, the -OH group can form an **intramolecular hydrogen bond** with the nitro group (-NO2) because they are close to each other on the benzene ring. This type of bonding occurs within the same molecule.
- In **p-nitrophenol**, the -OH group forms **intermolecular hydrogen bonds** with other p-nitrophenol molecules, which means the bonding occurs between different molecules.

**Hint**: Recall the difference between intramolecular (within the same molecule) and intermolecular (between different molecules) hydrogen bonding.

3. **Analyzing the Strength of Hydrogen Bonds**:
- The **intramolecular hydrogen bond** in o-nitrophenol is generally weaker than the **intermolecular hydrogen bonds** in p-nitrophenol.
- Strong intermolecular hydrogen bonding in p-nitrophenol leads to a higher boiling point, making it less volatile compared to o-nitrophenol.

**Hint**: Consider how the strength of hydrogen bonding affects boiling points and volatility.

4. **Conclusion**:
- Since o-nitrophenol has intramolecular hydrogen bonding, it is less stable and has a lower boiling point compared to p-nitrophenol, which has strong intermolecular hydrogen bonding. Thus, o-nitrophenol is more volatile.

**Hint**: Summarize the findings: intramolecular bonding leads to lower boiling points and higher volatility.

### Final Answer:
o-nitrophenol is more volatile than p-nitrophenol due to **intramolecular hydrogen bonding in o-nitrophenol**, which is weaker than the strong intermolecular hydrogen bonding in p-nitrophenol.