Born-Haber cycle is used to determine

Options

A. lattice energy of ionic crystals
B. Electron gain enthalpy
C. Electronegativity
D. Boht (a) and (b)

Answer

**Step-by-Step Solution:**

1. **Understanding the Born-Haber Cycle**: The Born-Haber cycle is a thermodynamic cycle used to analyze the energy changes involved in the formation of ionic compounds. It allows us to calculate the lattice energy of ionic crystals and the electron gain enthalpy.

2. **Components of the Cycle**:
- **Lattice Energy**: This is the energy released when gaseous ions combine to form an ionic solid. It is a measure of the strength of the forces between the ions in an ionic solid.
- **Ionization Energy**: The energy required to remove an electron from a neutral atom in the gas phase to form a cation.
- **Dissociation Energy**: The energy required to break a bond in a diatomic molecule (e.g., Cl2) to form gaseous atoms.
- **Electron Affinity**: The energy change that occurs when an electron is added to a neutral atom in the gas phase to form an anion.

3. **Applying the Born-Haber Cycle to Sodium Chloride (NaCl)**:
- Start with solid sodium (Na).
- Convert solid sodium to gaseous sodium (sublimation).
- Remove an electron from gaseous sodium to form Na⁺ (ionization).
- Dissociate Cl2 to form Cl atoms (dissociation).
- Add an electron to a Cl atom to form Cl⁻ (electron affinity).
- Combine Na⁺ and Cl⁻ to form solid NaCl (lattice energy).

4. **Conclusion**: The Born-Haber cycle allows us to calculate both the lattice energy of ionic compounds and the electron gain enthalpy. However, it does not directly provide information about electronegativity. Therefore, the correct answer to the question is option 4: both A (lattice energy) and B (electron gain enthalpy).