Final answer:
The solvation energy of KCl is calculated by subtracting the heat of solution from the crystal energy, which results in 629.8 kJ/mol. This compares to NaCl, whose lattice energy is 769 kJ/mol, indicating a stronger electrostatic attraction between ions.
Step-by-step explanation:
The correct answer is: Solvation energy of KCl = Crystal energy - Heat of solution, therefore option a) is correct. Using the given KCl crystal energy of 647 kJ/mol and the heat of solution of 17.2 kJ/mol, the solvation energy of KCl can be calculated as:
Solvation energy of KCl = 647 kJ/mol (Crystal energy) - 17.2 kJ/mol (Heat of solution) = 629.8 kJ/mol
In comparison, the NaCl lattice energy is 769 kJ/mol, which represents the energy required to separate one mole of solid NaCl into gaseous Na+ and Cl- ions. While the crystal energy of NaCl is higher than that of KCl, this does not directly determine solvation energy since the heat of solution for NaCl also plays a critical role in the calculation of its solvation energy.
Recall that the crystal (or lattice) energy reflects the stability of the ionic compound, and a higher crystal energy generally indicates a stronger electrostatic attraction between the ions within the solid state.