♦ A homogeneous mixture of two or more non-reactive substances is called a solution. A solution is prepared by dissolving one or more substances in another substance.
♦ Solute and solvent are the two components of the solution. The dissolved component is called solute whereas the component in which solute is dissolved is referred to as a solvent. A solution will contain only one solvent but can contain many solutes.
♦ Physical properties such as density and refractive index are uniform throughout the solution. However, these properties can vary depending on the solvent and solute ratio. For example, the physical properties of a 10 % (w/w) sugar solution will be different from 20% (w/w) sugar solution.
♦ Depending on the physical state of the solvent, a solution can exist in all three physical forms: Liquid, Solid, and Gas. All different types of solutions and their examples are summarized in the following table.
| Solution physical state | Solvent physical state | Solute physical state | Common term | Example | Remarks |
| Liquid | Liquid | Solid | Solid in liquid | Sugar-containing drinks | Solution of sugar (solute, solid) in water (solvent, solvent) |
| Liquid | Liquid | Liquid in liquid | Alcoholic drinks | Solution of alcohol (solute, liquid) in water (solvent, liquid) | |
| Liquid | Gas | Gas in liquid | Carbonated water | Solution of CO2 (solute, gas) in water (solvent, liquid) | |
| Solid | Solid | Solid | Solid in Solid | Steel | A solution of carbon atoms (solute, solid) in iron (solvent, solid) |
| Solid | Liquid | Liquid in Solid | Dental amalgam | Solution of Mercury (solute, liquid) in silver (solvent, solid) | |
| Solid | Gas | Gas in solid | Hydrogen in palladium | A solution of Hydrogen (solute, gas) in palladium (solvent, solid) | |
| Gas | Gas | Gas | Gas in Gas | Air | A solution of gases like CO2, O2 etc (solute, gas) in N2 (solvent, gas). Remember that N2 constitutes the highest proportion (≈ 78%) of air. |
