Monday Warm Up

• Find the molarity of a solution in which 5.5 mol of CaCl2 is dissolved to make 2 L aqueous CaCl2 solution.

• Find the molarity of a solution in which 2.0 g of Li2O is dissolved to make 0.5 L aqueous solution.

Review Warm Up

• Find the molarity of a solution in which 5.5 mol of CaCl2 is dissolved to make 2 L aqueous CaCl2 solution.

• Find the molarity of a solution in which 2.0 g of Li2O is dissolved to make 0.5 L aqueous solution.

Review Homework

Review Molality…

• Molality = expression of concentration measured by moles of solute per kilograms of solvent.

• FORMULA:

Example: Molality

• What is the molality of a solution containing 10.0 g of NaCl dissolved in 1.0 kg of water?

Guided Practice

• What is the molality of solution containing 30.0 g of benzene (C6H6) dissolved in 500.0 g of toluene?

Colligative Properties

• When ionic compounds dissolve in water, they became free ions, affecting the properties of water.

• These ionic compounds are known as electrolytes. When dissolved, these solutions are able to conduct electricity.

Water boiling with salt…

• Group Whiteboards: “Why does salt water boil at a higher temperature than regular water?”

Effect of solute on boiling point

• Boiling Point of Water is 100C.

• What effect will adding salt to the water have on the boiling point?

It will raise the boiling point.• Why?

As water forms strong bonds with the individual ions of salt, more energy is required to break those bonds and allow water to escape as vapor.

Effect of solute on freezing point

• At 0C, water freezes to form ice.• What effect will adding salt have on the

freezing point of water?It will lower the freezing point.

• Why?Solute particles interfere with the

attractive forces between the solvent particles preventing it from “falling into” its organized structure.

Think-Pair Share

• “What happens the boiling point of a solvent when a solute is added to it? Why does this happen?

• “What happens the freezing point of a solvent when a solute is added to it? Why does this happen?

MATH APPLICATION…

• By how many degrees will the boiling point increase??

Calculating Boiling Point Elevation

• Formula:

Example.

• What is the new boiling point of a 0.5 m aqueous NaCl solution?

Calculating Freezing Point Depression

• Formula:

Example.

• What is the new freezing point of a 0.625m aqueous CaCl2 solution?

Homework

• Textbook p. 469 #24-25, p.475 #33-36

Exit Slip #4

(1)What happens to the boiling point of water as NaCl is added to it?

(2)Why does this happen?

(3)Calculate the new boiling point of water for a 0.25m aqueous MgCl2 solution. (Kb = 0.512 C/m)