Hydrogen bond energy is equal to

Options

A. `3-7` cals
B. `30-70` cals
C. `3-10` kcals
D. `30-70` kcals

Answer

To determine the energy associated with hydrogen bonds, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Hydrogen Bonds**:
- Hydrogen bonds are a type of non-covalent interaction that occurs between a hydrogen atom covalently bonded to a highly electronegative atom (like oxygen or nitrogen) and another electronegative atom that has a lone pair of electrons.

2. **Nature of Hydrogen Bonds**:
- These bonds are considered electrostatic dipole-dipole interactions. They are weaker than covalent bonds because they do not involve the sharing of electrons.

3. **Comparison with Other Interactions**:
- Hydrogen bonds are stronger than other non-covalent interactions, such as Van der Waals forces, but still much weaker than covalent bonds.

4. **Energy Range of Hydrogen Bonds**:
- The energy associated with hydrogen bonds is typically estimated to be between 3 to 10 kilocalories per mole (kcal/mol). This range indicates that hydrogen bonds are relatively weak compared to covalent bonds, which can have energies ranging from 30 to 70 kcal/mol.

5. **Conclusion**:
- Therefore, the energy of hydrogen bonds is approximately 3 to 10 kcal/mol.

### Final Answer:
The hydrogen bond energy is equal to approximately **3 to 10 kcal/mol**.