Chapter 11 - Vapor Pressure and Gases

7/29/2019 Chapter 11 - Vapor Pressure and Gases

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ChemistryFIFTH EDITION

Chapter 11

Properties of Solutions


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Solutions

. . . the components of a mixture

are uniformly intermingled (the

mixture is homogeneous).


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Solution Composition

1.Molarity (M) =

2.Mass (weight) percent =

3.Mole fraction (A) =

4.Molality (m) =

moles of solute

liters of solution

mass of solute

mass of solution 100%

moles

total moles in solution

A

moles of solute

kilograms of solvent


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Figure 11.6The Solubilities

of Several Solidsas a Function of

Temperature


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Figure 11.7

The Solubilities of

Several Gases in

Water


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Steps in Solution Formation

Step 1 - Expanding the solute (endothermic)Step 2 - Expanding the solvent

(endothermic)

Step 3 - Allowing the solute and solvent to

interact to form a solution

(exothermic)

Hsoln = Hstep 1 + Hstep 2 + Hstep 3


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Figure 11.2

The Heat of a Solution


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Figure11.1

The Steps

in the

Dissolving

Process


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Henrys Law

P= kC

P= partial pressure of gaseous

solute above the solution

C= concentration of dissolved gask= a constant

The amount of a gas dissolved in a solution isThe amount of a gas dissolved in a solution isdirectly proportional to the pressure of the gasdirectly proportional to the pressure of the gas

above the solution.above the solution.


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Figure 11.5

A Gaseous Solute


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Raoults Law

Psoln= solventPsolvent

Psoln= vapor pressure of the solution

solvent

= mole fraction of the solvent

Psolvent= vapor pressure of thepure

solvent

The presence of a nonvolatile solute lowersThe presence of a nonvolatile solute lowers

the vapor pressure of a solvent.the vapor pressure of a solvent.


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Figure

11.11A Solution

Obeying

RaoultsLaw


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Colligative Properties

Depend only on the number, noton the identity, of the solute

particles in an ideal solution.

Boiling point elevation

Freezing point depression

Osmotic pressure

Fi 11 10


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Figure 11.10

The Presence of a Nonvolatile Solute Inhibits the

Escape of Solvent Molecules from the Liquid


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Boiling Point Elevation

A nonvolatile solute elevates the

boiling point of the solvent.

T=Kbmsolute

Kb = molal boiling point

elevation constant

m = molalit of the solute


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Freezing Point Depression

A nonvolatile solute depresses thefreezing point of the solvent.

T=Kfmsolute

Kf= molal freezing point

depression constantm = molality of the solute


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Osmotic Pressure

Osmosis: The flow of solventinto the solution through the

semipermeable membrane.

Osmotic Pressure: The excess

hydrostatic pressure on thesolution compared to the pure

solvent.


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If the external pressure is largerthan the osmotic pressure,

reverse osmosis occurs.

One application is desalination of

seawater.


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gure .

The Development of Osmotic Pressure


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Colligative Properties of

Electrolyte Solutions

T= imK

= iMRT

i =moles of particles in solution

moles of solute dissolved

vant Hoff factor, vant Hoff factor, ii, relates to the number of, relates to the number of

ions per formula unit.ions per formula unit.

NaCl = 2, KNaCl = 2, K22SOSO44 = 3= 3


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Colloids

Colloidal Dispersion (colloid): Asuspension of tiny particles in some

medium.

aerosols, foams, emulsions, sols

Coagulation: The addition of anelectrolyte, causing destruction of a

colloid.

Fi 11 3


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Figure 11.3

Orange and Yellow Spheres


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gure


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gure .

Total Vapor Pressure of a Solution


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Figure 11.13

Vapor Pressure for a Solution of

Two Volatile Liquids

gure


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gure .Ice in Equilibrium


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Figure 11.16Osmotic

Pressure


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Figure11.17

Osmosis

Figure 11 18


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Figure 11.18

Osmosis at Equilibrium

Figure 11 19


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Figure 11.19

A

Representation of the

Functioning

of an

Artificial

Kidney

11 20


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11.20

Reverse

Osmosis


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.A Representation of Two

Colloidal Particles


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Figure 11.25

The CottrellPrecipitator Installed

in a Smokestack

Chapter 11 - Vapor Pressure and Gases

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