Chapter 21 Colligative Properties: Part 2. Colligative Properties Properties determined by the number of solute particles in solution rather than the

Chapter 21

Colligative Properties:Part 2

Colligative Properties

Properties determined by the number of solute particles in solution rather than the type of particles.

Vapor pressure loweringVapor pressure loweringBoiling point elevation Boiling point elevation Freezing point depressionFreezing point depressionOsmotic pressureOsmotic pressure

Boiling Point Elevation

∆Tbp = (Kbp)(m)(#particles)

Boiling Point Elevation

∆Tbp = (Kbp)(m)(#particles)

# particlesMolecular solutes always = 1

Example: C6H12O6

Ionic solutes = # of ions in the compoundExample: BaCl2, Al2(SO4)3

Freezing Point Depression

∆Tfp = (Kfp)(m)(#particles)

Why is salt used on the roads instead of sugar?

What is the freezing point of a What is the freezing point of a 1.5m aqueous solution of NaCl?1.5m aqueous solution of NaCl?

∆Tfp = (Kfp)(m)(#particles)∆Tfp = (1.853°C∙kg/mol)(1.5mol/kg)(2)∆Tfp = 5.559°CNew Freezing Point = 0.000°C – 5.559°C

FP = -5.559°C

What is the boiling point of a 2.4m What is the boiling point of a 2.4m aqueous solution Ba(NOaqueous solution Ba(NO33))22??

BP = 103.708°C

∆Tbp = (Kb)(m)(#particles)∆Tbp = (0.515°C∙kg/mol)(2.4mol/kg)(3)∆Tbp = 3.708°CNew Boiling Point = 100.000°C + 3.708°C

97.5g of C97.5g of C1212HH2222OO1111 are dissolved in 185g of water. are dissolved in 185g of water. Find the freezing point and boiling point.Find the freezing point and boiling point.

FP = -2.854°C BP = 100.7931°C


FP = -2.854°C BP = 100.7931°C

A


FP = -2.854°C BP = 100.7931°C

A


FP = -2.854°C BP = 100.7931°C

A


FP = -2.854°C BP = 100.7931°C

A


FP = -2.854°C BP = 100.7931°C

14.0g of C14.0g of C1010HH88 are dissolved in 25.0g of benzene. are dissolved in 25.0g of benzene. Find the freezing point and boiling point.Find the freezing point and boiling point.

FP = -16.867°C BP = 91.169°C


FP = -16.867°C BP = 91.169°CA


FP = -16.867°C BP = 91.169°CA


FP = -16.867°C BP = 91.169°CA


FP = -16.867°C BP = 91.169°CA


FP = -16.867°C BP = 91.169°C

Homework

• Finish Worksheet: Vapor Pressure, Boiling Point and Freezing Point.

Documents

Chapter 21 Colligative Properties: Part 2. Colligative Properties Properties determined by the number of solute particles in solution rather than the