1. Define the term "enthalpy" and explain how it differs from "internal energy." Answer: Enthalpy is a thermodynamic quantity equivalent to the total heat content of a system. It is the sum of the internal energy added to the product of the pressure and volume of the system. It differs from internal energy in that enthalpy includes the energy required to make room for the system by displacing its environment and establishing its volume and pressure. 2. Describe the process of ligand exchange in coordination chemistry. Answer: Ligand exchange is a reaction where a ligand in a coordination complex is replaced by another ligand. This can occur through various mechanisms, including associative, dissociative, and interchange processes, depending on the strength of the metal-ligand bonds and the chemical environment. 3. What is the Born-Haber cycle, and how is it used to calculate lattice energy? Answer: The Born-Haber cycle is a hypothetical series of steps that represents the formation of an ionic compound from its constituent elements. It is used to calculate lattice energy by considering the energies of ionization, electron affinity, sublimation, and dissociation, as well as the energy released