A solution is a mixture of two or more substances that are evenly distributed throughout. Solutions form when solvent molecules surround solute ions or molecules, with water being the most common solvent. The rate of solubility is affected by factors like temperature, surface area, movement, and pressure, with temperature generally increasing solid solubility but decreasing gas solubility in liquids.

1. Notes: Solutions CW: There’s more than one Solution H: Working with Solutions

2. November 14, 2008 Solutions

3. Objectives Define solution, solubility, insoluble, solute and solvent Name the universal solvent Distinguish between an aqueous solution and a tincture Identify the factors that affect rates ofsolubility

4. Solution A mixture that appears to be a single substance but is made up of 2 or more substances that are evenly distributed throughout the mixture

5. Homogeneous Best mixed of the mixtures Particles are dissolved

6. Solutions are made up of Solutes – the substance that is dissolved Solvents – the substance that does the dissolving. It is always present in greater amount.

7. Can be more than 2 substances Soda – carbon dioxide gas, sugar, flavorings, food coloring are dissolved in water. Usually solutions are substances dissolved in a liquid but solutions may also be gasses and solids.

8. How Does a Solution Form? Solvent molecules attracted to surface ions. Each ion is surrounded by solvent molecules.

9. Solubility – the physical property of being able to dissolve Insoluble – a substance that can not be dissolved

10. Water is the universal solvent. Most things will dissolve in water. It is called an aqueous solution . Sometimes the solvent is alcohol. In this case it is called a tincture .

11. Solution rates vary Temperature Surface area Movement Pressure

12. Temperature The solubility of solid solutes in liquid solvents increases with increasing temperature.

13. Temperature The opposite is true of gases. Higher temperature drives gases out of solution. Carbonated soft drinks are more “bubbly” if stored in the refrigerator. Warm lakes have less O 2 dissolved in them than cool lakes.

14. Surface area The larger the surface area of a solid, the faster the rate of dissolving. The surface area of an object increases when it is broken down into smaller pieces.

15. Movement When a substance dissolves, it fills the available spaces between the closest water molecules. Stirring increases the rate the empty spaces can be filled.

16. Pressure The solubility of liquids and solids does not change with pressure. Increased pressure increases the solubility of gases.