3. Why do you put antifreeze in your car radiator? Can you cook spaghetti faster in salt water? Why is salt placed on roads to keep ice from forming?

4. All of these questions can be answered by colligative properties. Properties that depend on the concentration (numbers) of solute particles but not on their identity are called colligative properties. The presence of solutes affects the properties of solutions. Some of these properties are not dependent on the nature of the dissolved substance but only on how many dissolved particles are present.

5. Explains the value of putting antifreeze in your radiator to keep a car from overheating. Remember vapor pressure is the pressure caused by molecules in the gas phase that are in equilibrium with the liquid phase. The vapor pressure of a solvent containing a nonvolatile solute (doesn’t want to form a gas) is lower than the vapor pressure of the pure solvent (same temp.).

7. Increase number of solute particles Decreased opportunities for solvent particles to escape solution Result: Fewer solvent particles to evaporate and lower vapor pressure. More solute particles = Decreasing vapor pressure Remember colligative properties based on numbers of solute particles!!!!

8. Freezing-point depression is a colligative property of a liquid solution by which the freezing point of the solution is lower than that of the pure solvent. Explains why salt is placed on roads to keep ice from forming.

9. Remember with a solution, the vapor pressure is lower. This means the solution remains liquid over a larger temperature range. In other words, impurities in a substance cause a change in its phase diagram by making the liquid region bigger.

10. Explains how you can cook spaghetti faster in salt water. Boiling point elevation is a colligative property of a solution by which the solution’s boiling point is higher than that of the pure solvent.

11. Impact of solute on a colligative property. 1 mol of sugar = 1 mol Na + = 1 mol O 2- = 1 mol urea = 1 mol pickles All do the exact same thing!!! Same number of solute particles!!!