BackSolutions: Properties, Types, and Concentrations (Chapter 13 Study Notes)
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Solutions
Homogeneous Mixtures
A solution is a homogeneous mixture composed of two or more substances. Solutions are prevalent in everyday life, as most liquids and gases we encounter are actually solutions. Examples include ocean water (a solution of salt and other solids dissolved in water) and blood plasma (a solution of solids and gases in water).
Homogeneous mixture: A mixture with uniform composition throughout.
Solvent: The majority component in a solution.
Solute: The minority component in a solution.
Aqueous solution: A solution in which water is the solvent.
Example: Ocean water is a solution of salt (solute) in water (solvent).
Types of Solutions
Solutions can be formed from various combinations of solute and solvent phases, including gases, liquids, and solids. The following table summarizes common types of solutions:
Solute Phase | Solvent Phase | Example |
|---|---|---|
Gas | Gas | Air (mainly oxygen and nitrogen) |
Gas | Liquid | Soda water (CO2 and water) |
Liquid | Liquid | Vodka (ethanol and water) |
Solid | Liquid | Seawater (salt and water) |
Solid | Solid | Brass (copper and zinc alloy) |
Common Laboratory Solvents
Solvents are classified as polar or nonpolar, which determines the types of solutes they can dissolve. The principle "like dissolves like" applies: polar solvents dissolve polar solutes, and nonpolar solvents dissolve nonpolar solutes.
Common Polar Solvents | Common Nonpolar Solvents |
|---|---|
Water (H2O) | Hexane (C6H14) |
Acetone (CH3COCH3) | Diethyl ether (CH3CH2OCH2CH3) |
Methyl alcohol (CH3OH) | Toluene (C7H8) |
Polar solvents: Dissolve ionic and polar covalent compounds.
Nonpolar solvents: Dissolve nonpolar compounds such as oils and fats.
Example: Water is a common polar solvent forming aqueous solutions.
Solute and Solvent Roles
In a solution, the solute is present in a lesser amount, while the solvent is present in a greater amount. In solid/liquid solutions, the liquid is usually considered the solvent, regardless of the relative proportions.
Example: In seawater, water is the solvent and salt is the solute.
Additional info: Other solvents besides water are used in laboratories and industry, especially for dissolving nonpolar solutes.
