Chapter 15: Solutions Pages

A solution is a homogeneous mixture. – Remember that homogeneous means all in the same phase, you only see one thing. A solution may exist as a solid, liquid or gas. To be considered a solution it must meet the following requirements: 1. Does not separate upon standing. 2. Can not be filtered. 3. Light passes through it unaltered.

All solutions have two parts to them – Solute – the part of the solution that is being dissolved or the smallest part of the solution. – Solvent – the part of the solution that does the dissolving or the largest part of the solution. – It is possible for a solution to have more than one solute, but usually only one solvent. Two substances are said to be soluble or miscible if they have like bonds. “Likes dissolve Likes”.

The process of a solution forming happens when solvent molecules attack and overcome the intermolecular forces holding the solute particles together. We say that the solute dissociates into ions or smaller particles. To overcome these intermolecular forces it helps for the solvent molecules to have similar intermolecular forces in their bonds.

Factors Affecting Solution Formation – Types of Bonds: Ionic, Polar, Nonpolar Covalent – Size of Particle: Smaller dissolve easier than larger particles. – Temperature: For most warmer temperatures aids in solution formation. (Gases an exception) Factors Affect how fast a solution forms Stirring – provides more energy and collisions Temperature – provides more energy & collisions Particle Size – smaller particles dissolve faster.

Measuring the Concentration of a Solution – Concentrated: more solute, less solvent – Dilute: less solute, more solvent – Saturated: contains the most solute for a given amount of solvent at a specific temperature. – Unsaturated: can dissolve more solute. These are all qualitative measures of concentration, we will now look at some quantitative.

Colligative Properties Adding a solute to a solvent will change some of the physical properties of the solvent. Adding an electrolyte can make the solution conduct electricity. Adding a solute will lower the freezing point of the solvent. Adding a solute will raise the boiling point of the solution.