Ethy1 alcohol `(C_(2)H_(5)OH)` has higher boiling point than dimethyl ether `(CH_(3)-O-CH_(3))` although the molecular weight of both are same .

Options

A. intramolecular H-bonding
B. intermolecular H-bonding
C. dipole moment
D. lattice enthalpy.

Answer

To understand why ethyl alcohol (C₂H₅OH) has a higher boiling point than dimethyl ether (CH₃OCH₃) despite having the same molecular weight, we can analyze the molecular structures and the types of intermolecular forces present in each compound.

### Step-by-Step Solution:

1. **Identify the Structures**:
- Ethyl alcohol (C₂H₅OH) can be represented as CH₃-CH₂-OH.
- Dimethyl ether (CH₃OCH₃) can be represented as CH₃-O-CH₃.

2. **Examine Intermolecular Forces**:
- Ethyl alcohol has an -OH (hydroxyl) group, which is capable of forming hydrogen bonds due to the electronegativity of the oxygen atom.
- Dimethyl ether, on the other hand, has an ether functional group (R-O-R) but lacks hydrogen atoms bonded directly to the oxygen, which means it cannot form hydrogen bonds.

3. **Hydrogen Bonding in Ethyl Alcohol**:
- In ethyl alcohol, the hydrogen atom of the hydroxyl group can form hydrogen bonds with the oxygen of another ethyl alcohol molecule. This results in strong intermolecular forces.
- These hydrogen bonds create a network of interactions that hold the molecules together more tightly.

4. **Absence of Hydrogen Bonding in Dimethyl Ether**:
- In dimethyl ether, all hydrogen atoms are bonded to carbon atoms, which do not have the same ability to form hydrogen bonds with the oxygen atom.
- As a result, the intermolecular forces in dimethyl ether are primarily weaker van der Waals forces.

5. **Impact on Boiling Points**:
- The presence of strong hydrogen bonds in ethyl alcohol means that more energy (in the form of heat) is required to break these interactions when the substance is heated, leading to a higher boiling point.
- Conversely, dimethyl ether, with its weaker intermolecular forces, requires less energy to overcome these forces, resulting in a lower boiling point.

6. **Conclusion**:
- Therefore, ethyl alcohol has a higher boiling point than dimethyl ether due to the presence of intermolecular hydrogen bonding in ethyl alcohol, which is absent in dimethyl ether.

### Final Answer:
Ethyl alcohol has a higher boiling point than dimethyl ether because of the presence of intermolecular hydrogen bonding in ethyl alcohol, which requires more energy to break compared to the weaker van der Waals forces in dimethyl ether.