1. COLLIGATIVE PROPERTIES STRUCTURE MEETS FUNCTION: WHAT PROPERTIES DO SOLUTIONS HAVE AND WHY?

2. LIQUIDS Definite volume, no definite shape. Properties of solutions: Volatility: tendency of a solution to turn into gas at the surface. Measured by vapor pressure. Boiling point: the point at which a solution goes to gas phase. Freezing point: the point at which a solution becomes solid.

3. WHAT MAKES LIQUIDS STAY LIQUIDS Polarity: intramolecular forces between polar molecules causes them to stick together!

4. COMPARE TO A GAS

5. TODAY’S INVESTIGATION How does adding a solvent to water change its boiling point? Control: Independent variable: How must we measure the independent variables to make sure the effect is the same? Dependent variable:

6. TYPES OF SOLUTES Covalent: sugar (C 12 H 22 O 11 ) Ionic: a. KCl b. CaCl 2 Which solute has the greatest effect on the boiling point of water?

7. DATA ANALYSIS & CONCLUSION: How did each solute affect the boiling point of water? What is the trend? What if we had observed freezing point instead?

8. NEXT STEPS: How to calculate freezing point elevation and boiling point depression. Ways to measure concentration of solutions: 1)Review Molarity 2)Molality 3)Mole Fraction 4)ppb and ppm HW: Find how to calculate each of the following!