1. Electrolytes

2. Ionic compounds Break down into positive and negative ions Conduct electricity Essential to us !!!

4. Strong vs. Weak Electrolytes Weak—electrolytes partially breaking down in a solution Strong—electrolytes completely breaking down in a solution

5. Nonelectrolytes Molecular compounds Break down into molecules Do NOT conduct electricity

7. Colligative Properties

8. What are colligative properties? Physical properties Based on # of solute particles, NOT identity!!! 4 properties  Vapor Pressure Lowering  Freezing Point Depression  Boiling Point Elevation  Osmotic Pressure

9. 1) Vapor Pressure Lowering Nonvolatile vs. volatile chemicals Nonvolatile Not likely to be a gas Takes awhile for gas particles to evaporate Volatile Gas particles evaporate quickly Vapor Pressure Pressure exerted from gas molecules on a liquid Characteristic of a liquid

11. Volatile vs. Nonvolatile Liquids  Volatile Liquids WEAK intermolecular forces High vapor pressure Ex. Gasoline, alcohols, “Whoosh Bottle”  Nonvolatile Liquids STRONG intermolecular forces Low vapor pressure

12. More Vapor Pressure…. INCREASED vapor pressure Pure solvent Particles can easily move between the liquid and gas phase to create an equal amount of particles in each phase (equilibrium) DECREASED vapor pressure Solvent + solute Number of particles in the solution is increased Less water/solvent can evaporate

14. 2) Freezing Point Depression “difference between freezing point of a pure solvent and a solution containing a nonelectrolyte.” Difference between Freezing point of pure solvent AND Freezing point of solvent + solute/substance **Adding a solute/substance LOWERS the freezing point.

18. 3) Boiling Point Elevation Boiling point— Temperature where a liquid’s vapor pressure = atmosphere pressure **Boiling point changes result from changes in vapor pressure. “difference between boiling point of a pure solvent and a solution containing a nonelectrolyte” Difference between Boiling point of pure solvent AND Boiling point of solvent + solute/substance

19. Boiling Point and Vapor Pressure Substances with low vapor pressure More energy needed for vapor pressure = atmospheric pressure SO Boiling point INCREASES ** Solutes in a solution LOWER vapor pressure so boiling point INCREASES !

20. Osmosis Semipermeable membrane Membrane selects what particles can go through and blocks other particles Movement of water through a semipermeable membrane Based on solute concentration (High  Low solute concentration)

23. 4) Osmotic Pressure Pressure exerted by solute particles resisting osmosis INCREASE osmotic pressure High solute concentration Water drawn in DECREASE osmotic pressure Low solute concentration Water driven out

25. Electrolytes and Colligative Properties Electrolytes GREATLY influence colligative properties. Electrolytes---dissociate into ions in solution Ions increase the NUMBER of solute particles in a solvent.

26. Homework Electrolytes Worksheet Colligative Properties Worksheet