Problem 13 - Chemistry: The Central Science

Question

In general, the attractive intermolecular forces between solvent and solute particles must be comparable or greater than solute-solute interactions for significant solubility to occur. Explain this statement in terms of the overall energetics of solution formation.

Step-by-Step Solution

Answer

In summary, for significant solubility to occur, the attractive intermolecular forces between solvent and solute particles must be comparable or greater than solute-solute interactions. This is because the overall energetics of solution formation depend on a balance between breaking solute-solute and solvent-solvent interactions, and forming solvent-solute interactions. If the energy released from solvent-solute interactions is insufficient to break solute-solute interactions, the solubility will be low. Therefore, stronger attractive forces between solvent and solute particles are needed for efficient dissolution and higher solubility.

Step 1: Understand the meaning of the statement

The statement says that for significant solubility to occur, the intermolecular forces between solvent and solute particles must be comparable or greater than the solute-solute interactions. This means that the attractive forces between the solute and solvent particles should be strong enough to break the interactions between the solute particles and dissolve them in the solvent.

Step 2: Analyze the energetics of solution formation

When a solute is dissolved in a solvent, there are three main processes that occur: 1. Breaking solute-solute interactions: Energy is required to break the attractive forces between solute particles. 2. Breaking solvent-solvent interactions: Energy is required to break the attractive forces between solvent particles. 3. Forming solvent-solute interactions: Energy is released when new attractive forces are formed between solute and solvent particles. The overall energetics of solution formation is determined by the balance between these three energy changes.

Step 3: Relate energetics to solubility

For significant solubility to occur, the energy released by forming solvent-solute interactions should be comparable or greater than the energy required to break solute-solute interactions. Mathematically, this can be represented as: \( \Delta H_{solute-solvent} \geq \Delta H_{solute-solute} \), where \(\Delta H_{solute-solvent} \) is the energy change associated with forming solvent-solute interactions and \(\Delta H_{solute-solute} \) is the energy change associated with breaking solute-solute interactions. If the energy released from the formation of solvent-solute interactions is small, that means it might not be enough to break the solute-solute interactions and dissolve the solute, resulting in low solubility.

Step 4: Conclusion

In conclusion, the attractive intermolecular forces between solvent and solute particles should be comparable or greater than solute-solute interactions for significant solubility to occur. This is because the overall energetics of solution formation depend on the balance between the energy changes associated with breaking solute-solute and solvent-solvent interactions, and the energy released by forming solvent-solute interactions. If the attractive forces between the solvent and solute particles are not strong enough, there will be insufficient energy to break the solute-solute interactions, resulting in low solubility.