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Slide 1 of 22 Chemistry 16.3. © Copyright Pearson Prentice Hall Slide 2 of 22 Colligative Properties of Solutions The wood frog is a remarkable creature.

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Presentation on theme: "Slide 1 of 22 Chemistry 16.3. © Copyright Pearson Prentice Hall Slide 2 of 22 Colligative Properties of Solutions The wood frog is a remarkable creature."— Presentation transcript:

1 Slide 1 of 22 Chemistry 16.3

2 © Copyright Pearson Prentice Hall Slide 2 of 22 Colligative Properties of Solutions The wood frog is a remarkable creature because it can survive being frozen. Scientists believe that a substance in the cells of this frog acts as a natural antifreeze, which prevents the cells from freezing. You will discover how a solute can change the freezing point of a solution. 16.3

3 © Copyright Pearson Prentice Hall Colligative Properties of Solutions > Slide 3 of 22 Vapor-Pressure Lowering What are three colligative properties of solutions? 16.3

4 Slide 4 of 22 © Copyright Pearson Prentice Hall Colligative Properties of Solutions > Vapor-Pressure Lowering A property that depends only upon the number of solute particles, and not upon their identity, is called a colligative property. 16.3

5 © Copyright Pearson Prentice Hall Slide 5 of 22 Colligative Properties of Solutions > Vapor-Pressure Lowering Three important colligative properties of solutions are vapor-pressure lowering boiling-point elevation freezing-point depression 16.3

6 Slide 6 of 22 © Copyright Pearson Prentice Hall Colligative Properties of Solutions > Vapor-Pressure Lowering In a pure solvent, equilibrium is established between the liquid and the vapor. 16.3

7 Slide 7 of 22 © Copyright Pearson Prentice Hall Colligative Properties of Solutions > Vapor-Pressure Lowering In a solution, solute particles reduce the number of free solvent particles able to escape the liquid. Equilibrium is established at a lower vapor pressure. 16.3

8 © Copyright Pearson Prentice Hall Slide 8 of 22 Colligative Properties of Solutions > Vapor-Pressure Lowering The decrease in a solution’s vapor pressure is proportional to the number of particles the solute makes in solution. 16.3

9 Slide 9 of 22 © Copyright Pearson Prentice Hall Colligative Properties of Solutions > Vapor-Pressure Lowering Three moles of glucose dissolved in water produce 3 mol of particles because glucose does not dissociate. 16.3

10 Slide 10 of 22 © Copyright Pearson Prentice Hall Colligative Properties of Solutions > Vapor-Pressure Lowering Three moles of sodium chloride dissolved in water produce 6 mol of particles because each formula unit of NaCl dissociates into two ions. 16.3

11 Slide 11 of 22 © Copyright Pearson Prentice Hall Colligative Properties of Solutions > Vapor-Pressure Lowering Three moles of calcium chloride dissolved in water produce 9 mol of particles because each formula unit of CaCl 2 dissociates into three ions. 16.3

12 © Copyright Pearson Prentice Hall Colligative Properties of Solutions > Slide 12 of 22 Freezing-Point Depression What factor determines the amount by which a solution’s vapor pressure, freezing point, and boiling point differ from those properties of the solvent? 16.3

13 Slide 13 of 22 © Copyright Pearson Prentice Hall Colligative Properties of Solutions > Freezing-Point Depression The difference in temperature between the freezing point of a solution and the freezing point of the pure solvent is the freezing-point depression. 16.3

14 © Copyright Pearson Prentice Hall Slide 14 of 22 Colligative Properties of Solutions > Freezing-Point Depression The magnitude of the freezing-point depression is proportional to the number of solute particles dissolved in the solvent and does not depend upon their identity. 16.3

15 Slide 15 of 22 © Copyright Pearson Prentice Hall Colligative Properties of Solutions > Freezing-Point Depression The freezing-point depression of aqueous solutions makes walks and driveways safer when people sprinkle salt on icy surfaces to make ice melt. The melted ice forms a solution with a lower freezing point than that of pure water. 16.3

16 Slide 16 of 22 © Copyright Pearson Prentice Hall Colligative Properties of Solutions > Boiling-Point Elevation The difference in temperature between the boiling point of a solution and the boiling point of the pure solvent is the boiling-point elevation. The same antifreeze added to automobile engines to prevent freeze-ups in winter, protects the engine from boiling over in summer. 16.3

17 Slide 17 of 22 © Copyright Pearson Prentice Hall Colligative Properties of Solutions > Boiling-Point Elevation The magnitude of the boiling-point elevation is proportional to the number of solute particles dissolved in the solvent. The boiling point of water increases by 0.512°C for every mole of particles that the solute forms when dissolved in 1000 g of water. 16.3

18 © Copyright Pearson Prentice Hall Slide 18 of 22 Section Quiz -or- Continue to: Launch: Assess students’ understanding of the concepts in Section 16.3 Section Quiz

19 © Copyright Pearson Prentice Hall Slide 19 of Section Quiz. 1. Which of the following is NOT a colligative property of a.vapor-pressure lowering b.freezing-point depression c.boiling-point elevation d.solubility elevation

20 © Copyright Pearson Prentice Hall Slide 20 of Section Quiz. 2. Choose the correct word for the space: The magnitude of each colligative property of solutions is proportional to the __________ solute dissolved in the solution. a.type of b.number of particles of c.molar volume of d.particle size of the

21 © Copyright Pearson Prentice Hall Slide 21 of Section Quiz. 3. The decrease in vapor pressure when a solute is added to a liquid is due to a.attractive forces between solvent particles. b.repulsion of the solute particles by the solvent particles. c.dissociation of the solvent particles. d.attractive forces between solvent and solute particles.

22 © Copyright Pearson Prentice Hall Slide 22 of Section Quiz. 4. You have 500 mL of 1M solutions of NaCl, Na 2 SO 4, Na 3 PO 4, and Al 2 (SO 4 ) 3. Which solution will have the highest boiling point? a.NaCl(aq) b.Na 2 SO 4 (aq) c.Na 3 PO 4 (aq) d.Al 2 (SO 4 ) 3 (aq)

23 END OF SHOW


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