When an ionic compound is dissolved in water (polar solvent), it breaks up into its constituent ions. The given ionic compound will be dissolved in water if its hydration energy is more than lattice energy . IF hydration energy is less than lattice energy then ionic compound is usually either sparingly soluble or insoluble in water.
Which of the following ionic compound is having maximum lattice energy :

Options

A. NaF
B. `MgF_(2)`
C. `AlF_(3)`
D. `KF`

Answer

To determine which ionic compound has the maximum lattice energy, we need to analyze the charges of the cations and anions involved in each compound, as well as the ionic radii. Lattice energy is influenced by the charges of the ions and the distance between them.

### Step-by-Step Solution:

1. **Understanding Lattice Energy**:
Lattice energy is the energy released when gaseous ions combine to form an ionic solid. It is directly proportional to the product of the charges of the ions and inversely proportional to the distance between them (ionic radii).

**Hint**: Remember that higher charges lead to stronger attractions and thus higher lattice energy.

2. **Identify the Ionic Compounds**:
We have four ionic compounds to consider:
- NaF (Sodium Fluoride)
- MgF2 (Magnesium Fluoride)
- AlF3 (Aluminum Fluoride)
- KF (Potassium Fluoride)

3. **Determine the Charges of Ions**:
- NaF: Na⁺ (charge +1), F⁻ (charge -1)
- MgF2: Mg²⁺ (charge +2), F⁻ (charge -1)
- AlF3: Al³⁺ (charge +3), F⁻ (charge -1)
- KF: K⁺ (charge +1), F⁻ (charge -1)

**Hint**: Focus on the cation charges, as they significantly affect the lattice energy.

4. **Calculate the Product of Charges**:
- NaF: 1 * 1 = 1
- MgF2: 2 * 1 = 2
- AlF3: 3 * 1 = 3
- KF: 1 * 1 = 1

**Hint**: The higher the product of the charges, the higher the potential lattice energy.

5. **Compare the Lattice Energies**:
Based on the product of charges:
- NaF has a product of 1
- MgF2 has a product of 2
- AlF3 has a product of 3
- KF has a product of 1

From this comparison, AlF3 has the highest product of charges.

6. **Conclusion**:
Since AlF3 has the highest charge product (3), it will have the maximum lattice energy among the given options.

**Final Answer**: The ionic compound with the maximum lattice energy is **AlF3**.