(a) In Equation 13.1, which of the enthalpy terms for dissolving an ionic solid would correspond to the lattice energy? (b) Which energy term in this equation is always exothermic?

Verified step by step guidance

1. Step 1: Understand the process of dissolving an ionic solid. When an ionic solid dissolves in water, the process can be broken down into three main steps: breaking the ionic lattice, separating the ions, and hydrating the ions.
2. Step 2: Identify the enthalpy terms involved in the dissolution process. The enthalpy change for dissolving an ionic solid (ΔH_solution) can be expressed as the sum of the lattice energy (ΔH_lattice) and the hydration energy (ΔH_hydration).
3. Step 3: Define lattice energy. Lattice energy is the energy required to break the ionic bonds in the solid to separate the ions, which is an endothermic process. Therefore, in Equation 13.1, the lattice energy corresponds to the enthalpy term that represents the energy needed to break the ionic lattice.
4. Step 4: Define hydration energy. Hydration energy is the energy released when ions are surrounded by water molecules. This process is exothermic because energy is released when new interactions between ions and water molecules are formed.
5. Step 5: Determine which energy term is always exothermic. In the dissolution process, the hydration energy is always exothermic because it involves the formation of ion-dipole interactions between the ions and water molecules.