The more negative \(\Delta E_{\text {solvation }}\) is, the more likely a solute will dissolve. Explain.

Enthalpy change, denoted as can either increase or decrease during a chemical process, such as the dissolution of a solute in a solvent. A negative enthalpy change (means that the process is exothermic, releasing heat to the surroundings. It indicates that the energy required to break the bonds in the solute and in the solvent is less than the energy released when new bonds are formed between the solute and solvent molecules. In contrast, a positive enthalpy change (An exothermic dissolution process with a negative enthalpy change often enhances the solute's solubility, consistent with the idea that forming stronger attractions releases energy, which is favored thermodynamically. On the other hand, when the enthalpy change is positive, energy is absorbed from the surroundings (endothermic process), and this might work against solubility unless compensated by a significant increase in entropy.

Entropy change (denoted as refers to the change in the level of disorder or randomness in a system. When a solute dissolves in a solvent, the entropy typically increases because the molecules of the solute are spread out into the solvent, creating a more disordered system. Solids and liquids are usually more organized, whereas their constituent particles in solution have greater freedom of movement. The tendency for an increase in entropy during dissolution suggests that nature favors processes where systems become more disorganized. An important principle to remember is that spontaneous processes tend to increase the entropy of the universe. Hence, even if the enthalpy change for a dissolution process is not favorable (endothermic), the overall process may still be spontaneous if there is a significant increase in entropy. If both the enthalpy change is negative and the entropy increases, the dissolution would be highly favored.

The dissolution process involves dissolving a solid, liquid or gaseous solute into a solvent to form a solution. This process is governed by solute-solvent interactions and can be broken down into three steps:

• Separation of solute particles: Energy is used to overcome the forces holding the solute particles together.
• Separation of solvent molecules: Similarly, energy is expended to overcome the intermolecular forces between solvent molecules to make space for the solute particles.
• Formation of new solute-solvent interactions: Energy is released when solute particles interact with solvent molecules to form a homogeneous mixture.

The solubility of a substance is highly dependent on whether the overall solvation process releases or absorbs energy. If the energy required to separate solute and solvent particles is less than the energy released when they come together to form new interactions, the process will tend to be spontaneous, leading to a greater likelihood that the solute will dissolve.

Solute-solvent interactions are a critical factor affecting the solvation energy and, subsequently, the solubility of a compound. These interactions can be electrostatic, hydrogen bonding, van der Waals forces or even covalent in nature. The strength and nature of these interactions determine how much energy is released when a solute dissolves in a solvent. If the interactions between solute and solvent molecules are strong, they will release more energy upon formation, leading to a negative solvation energy. This release of energy is one reason compounds with substantial ionic or polar character often have good solubility in polar solvents, where the solvent molecules can stabilize the solute ions or polar molecules effectively. In summary, understanding both the type and magnitude of solute-solvent interactions can provide insight into the solvation energy and help predict the ease with which a solute will dissolve in a particular solvent.