Solubility
Related Examples and Practice Problems
Additional Worked Out Examples/ Practice
Identifying classification types: Differentiation between elements, compounds or mixtures and homogeneous and heterogenous mixtures
Separation techniques: Selected and explaining limitation of appropriate separation
Relating Properties to Composition: Predicting classification based on descriptive properties
Topic Summary & Highlights
and Help Videos
Core Concept
The phrase "like dissolves like" means that polar solvents (like water) dissolve polar or ionic substances, while nonpolar solvents (like hexane) dissolve nonpolar substances. This principle is based on the compatibility of intermolecular forces between the solvent and solute, where similar types of forces lead to better solubility.
Also check out Solubility Rules.
Practice Tips
Review the types of intermolecular forces (e.g., hydrogen bonding, dipole-dipole, and London dispersion) and their role in solubility.
Practice determining whether a molecule is polar or nonpolar, as polarity is critical in predicting solubility.
Core Concept
The Like Dissolves Like Rule: A Guiding Principle
One of the key ideas in solubility is the "like dissolves like" rule. This rule states that polar solutes tend to dissolve well in polar solvents, and nonpolar solutes tend to dissolve well in nonpolar solvents. Let's delve deeper into the reasons behind this:
Polarity Matters: Polar molecules have uneven distribution of electrical charge. They can interact with each other through attractive forces called dipole-dipole interactions or hydrogen bonding. When a polar solute encounters a polar solvent, these interactions can overcome the attractive forces holding the solute particles together, leading to dissolution.
Nonpolarity in Action: Nonpolar molecules, on the other hand, lack significant differences in charge distribution. They interact with each other through weak London dispersion forces. When a nonpolar solute encounters a nonpolar solvent, the intermolecular forces between solute and solvent are similar, allowing for good mixing.
Factors Affecting Solubility
While the "like dissolves like" rule is a helpful starting point, several other factors can influence solubility:
Temperature: Generally, increasing temperature increases the kinetic energy of the solvent molecules, making them more effective at breaking apart the solute's intermolecular forces and promoting dissolution. (Exceptions exist!)
Pressure: For gases dissolving in liquids, increased pressure can force more gas molecules into the solution.
Intermolecular Forces: The strength of the intermolecular forces within the solute and between the solute and solvent plays a role. Stronger forces require more energy to overcome, leading to lower solubility.
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