Which of the following statements best describes the phrase “like dissolves like”?
The only true solutions are formed when water dissolves a polar solute.
A solvent will dissolve a solute that has a similar mass.
The only true solutions are formed when water dissolves a nonpolar solute
A solvent and a solute with similar intermolecular forces will easily make a solution.
The Correct Answer and Explanation is:
The correct answer is:
A solvent and a solute with similar intermolecular forces will easily make a solution.
Explanation:
The phrase “like dissolves like” is a fundamental principle in chemistry that refers to the ability of solvents to dissolve solutes based on the similarity of their intermolecular forces or polarity. It means that substances with similar chemical characteristics—particularly polarity—are more likely to dissolve in each other and form a homogeneous mixture, or solution.
Why?
- Intermolecular Forces and Polarity:
Molecules interact through various types of intermolecular forces, such as hydrogen bonding, dipole-dipole interactions, and London dispersion forces. Polar molecules have permanent dipoles, meaning they have a partial positive and negative end, while nonpolar molecules do not. - Solvent-Solute Interactions:
When a solute dissolves in a solvent, the solvent molecules surround and interact with the solute molecules. For a solution to form, these solvent-solute interactions must be strong enough to overcome the forces holding the solute molecules together and the forces holding the solvent molecules together. - “Like” Means Similar Polarity:
- Polar solvents (like water) dissolve polar solutes or ionic compounds because both have strong dipole interactions or ionic interactions.
- Nonpolar solvents (like hexane) dissolve nonpolar solutes because of similar weak London dispersion forces.
- Polar solvents do not effectively dissolve nonpolar solutes, and vice versa, because their intermolecular forces are very different.
Why the other options are incorrect:
- “The only true solutions are formed when water dissolves a polar solute.”
This is too restrictive and only covers one specific case. While water is a polar solvent and dissolves many polar solutes, solutions are not limited to this. Nonpolar solvents dissolve nonpolar solutes as well. - “A solvent will dissolve a solute that has a similar mass.”
Mass similarity has little to no relevance in solubility. Solubility depends primarily on the nature of the intermolecular forces, not molecular mass. - “The only true solutions are formed when water dissolves a nonpolar solute.”
This is incorrect because water, a polar solvent, generally does not dissolve nonpolar solutes well.
In summary, “like dissolves like” refers to the fact that solvents dissolve solutes best when they have similar intermolecular forces or polarity, enabling favorable interactions that stabilize the solution.
