UNIT 3 SOLUTIONS AND GASES 3 UNIT 3 SOLUTIONS AND GASES 3.6 How do we calculate the concentration of a solution? April 27, 2011 AIM: How do colligative properties affect solubility of substances? DO NOW: Define the following words: Solute Solvent Solution

COLLIGATIVE PROPERTIES What are they? properties that depends on the number of solute particles present in a solution. Colligative properties include vapor pressure, boiling point, freezing point, and osmotic pressure.

LAB Directions: Access EXPLORELEARNING.COM USERNAME: asphigh PASSWORD: asphigh Press on CRII Choose Colligative Properties Lab Start you lab

YOU WILL Measure the freezing point and boiling point of a solution. Observe how adding a solute changes the vapor pressure, boiling point, and freezing point of a solution. Relate the effects of a solute to its concentration. Observe and predict how a solute will dissociate in water. Relate the effects of a solute to the way it dissociates.

DISCUSSION QUESTIONS Which solute has the greatest effect on the vapor pressure, boiling point, and freezing point of the solution? Why? How does the chemical formula of an ionic compound relate to the number of particles it dissociates into when dissolved in a solution? At the molecular level, what is happening when water boils? How would this process be affected by the addition of a solute that does not evaporate? [The answer to this question as well as the next two questions is discussed in the Scientific Background below.] At a molecular level, what is happening when water freezes? How would this process be affected by the addition of a solute that does not evaporate? At a molecular level, what is happening during osmosis? How would this process be affected by the addition of more solute?

INDEPENDENT PRACTICE Complete the Independent Practice PLACE the lab in the CHEMICAL REACTIONS BIN YOU HAVE UNTIL FRINDAY, APRIL 29, 2011 TO HAND IN: WORK FROM UNIT 6 (before the break) any missing labs Test corrections