When lithium iodide (LiI) is dissolved in water, the solution becomes hotter. b. What can you conclude about the relative magnitudes of the lattice energy of lithium iodide and its heat of hydration?

Key Concepts

Lattice Energy

Lattice energy is the amount of 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 compound. A higher lattice energy indicates stronger ionic bonds, which typically results in a more stable compound. In the case of lithium iodide, the lattice energy is significant because it influences the overall energy changes when the compound dissolves in water.

Heat of Hydration

The heat of hydration refers to the energy change that occurs when ions are surrounded by water molecules and solvate. This process involves the formation of ion-dipole interactions between the ions and water, which releases energy. A large heat of hydration indicates that the solvation process is energetically favorable, contributing to the overall temperature change observed when an ionic compound dissolves in water.

Energy Balance in Dissolution

The energy balance in dissolution involves comparing the lattice energy of the ionic compound with the heat of hydration. If the heat of hydration is greater than the lattice energy, the overall process is exothermic, resulting in a temperature increase in the solution. In the case of lithium iodide, the observation that the solution becomes hotter suggests that the heat of hydration exceeds the lattice energy, indicating a favorable dissolution process.