Unit 3.7: Notes on Solutions and Mixtures

Mixture: A physical combination of two or more substances that are not chemically bonded.
Solution: A specific type of mixture that is homogeneous, meaning it has a uniform composition throughout. Commonly formed by dissolving a solute in a solvent.

Solutions can exist in any phase:
- Solid solute in liquid solvent (most common)
- Gas dissolved in a liquid
- Solid dissolved in a gas
Focus of discussion: Aqueous Solutions
- Definition: Solutions where water is the solvent.
- Solute: The substance being dissolved.
- Solvent: The substance in which the solute is dissolved (often water in aqueous solutions).

Molarity: A way to express the concentration of a solution.
- Formula: M = \frac{\text{moles of solute}}{\text{liters of solution}}
Example Observation: When only pure water is present, molarity is 0.0. When solute is added, the concentration increases.

Adding Solvent: When more solvent (water) is added:
- Moles of solute remain constant.
- Volume of solution increases.
- Result: Molarity decreases because M is inversely proportional to the volume of solution.
Evaporation of Solvent: If a solution sits out and water evaporates:
- The concentration of the solution increases because the volume decreases while moles of solute stay the same.
- Result: Molarity increases as solvent evaporates.

The video ends with practice problems to consolidate understanding of molarity calculations and concentration concepts.
Important to review material from previous chemistry knowledge (Chem 1) for thorough comprehension.