Solubility of a substance is its maximum amount that can be dissolved in a specified amount of solvent at a specified temperature. Solubility of a substance depends upon the nature of solute and solvent as well as temperature and pressure. A saturated solution is a solution that is in equilibrium with an excess of solid at a given temperature. A solution that contains a high concentration of solute than does a saturated solution is known as supersaturated solution. If a small crystal of solute is added to a supersaturated solution, the solid will at once crystallize out and an equilibrium will be established. This is known as seeding. More the dielectric constant of a solvent, more is the solubility of polar covalent or ionic compounds in it. Some covalent compounds dissolve in water due to hydrolysis while some other covalent solids dissolve in water due to hydrogen bonding. Ionic compounds dissolve in polar solvents while covalent compounds dissolve in non-polar solvents and this is known as like dissolves like.

The solubilities of ionic compounds often but not always increase with temperature, because energy is required to pull the molecules or ions away from the crystal lattice (lattice energy) \(\Delta H_L\).

Energy is also liberated due to solvation of the solute particles. If the solvent is water, the energy liberated due to solvation is known as hydration energy \(\Delta H_h\).

The energy change when one mole of ionic compound dissolves in water is \(\Delta H_{sol}\).

\[\Delta H_{sol} = \Delta H_h - \Delta H_L\]

Since the hydration energies of the ions and the lattice energy are exothermic changes, they have a negative sign. If \(\Delta H_h\) is more than \(\Delta H_L\), then \(\Delta H_{sol}\) will be negative and the ionic crystal dissolves exothermically.

Which statement best explains the meaning of the phrase like dissolves like?

A solvent and solute with similar intermolecular forces will readily form a solution

The correct answer is option 2. A solvent and solute with similar intermolecular forces will readily form a solution.

"Like dissolves like" is a fundamental principle in chemistry that guides the process of dissolution, which occurs when a solute (substance being dissolved) is mixed with a solvent (the dissolving medium) to form a solution.

Here is a more detailed explanation:

Similar Intermolecular Forces: The phrase suggests that substances with similar types of intermolecular forces tend to dissolve in each other. For example, polar solutes (those with permanent dipoles) dissolve readily in polar solvents, while nonpolar solutes (those without permanent dipoles) dissolve better in nonpolar solvents. This preference arises because substances with similar intermolecular forces are more compatible with each other.

Hydrophilic and Hydrophobic Interactions: Polar solvents, like water, have molecules with dipoles due to differences in electronegativity between atoms (like oxygen and hydrogen in water). These polar solvents can interact with other polar molecules (hydrophilic interactions) but have limited interactions with nonpolar molecules (hydrophobic interactions). On the other hand, nonpolar solvents lack dipoles and cannot effectively interact with polar solutes but readily dissolve nonpolar solutes.

Efficiency of Dissolution: When substances with similar intermolecular forces come into contact, their molecules can mix more efficiently, leading to the formation of a solution. This efficiency is due to the ability of molecules to overcome intermolecular forces in both the solute and solvent, facilitating their dispersion and mixing at the molecular level.

Applications: The principle of "like dissolves like" finds applications in various areas of chemistry, including organic chemistry, where it guides the selection of solvents for different reactions based on the polarity of reactants and products. It also helps in understanding phenomena like micelle formation in detergents and the solubility of gases in liquids.

In summary, "like dissolves like" serves as a guiding principle for predicting solubility behavior based on the similarity of intermolecular forces between solutes and solvents.