Physical Chemistry I - PowerPoint Presentation

Slide1

Physical Chemistry I(TKK-2246)

14/15 Semester 2

Instructor: Rama

Oktavian

Email: rama.oktavian86@gmail.com

Office Hr.:

M – F.13-15Slide2

Outlines

1.

Review

2. Liquid-liquid equilibria (2-components)

3. Liquid-liquid equilibria (3-components)

4.

Ternary diagramsSlide3

ReviewSlide4

Review

Ch. 12Equilibrium condition

the chemical potential of each substance must have the same value in every phase in which that substance appears

a state in which there are no observable changes as time goes by.Slide5

Review

Ch. 12Phase diagramSlide6

Review

Ch. 12Phase rule

the phase rule for a one-component system

Gibbs Phase RuleSlide7

Review

Ch. 13Solution

Solution - homogeneous mixture of chemical species

One phaseSlide8

Review

Ch. 13Raoult’s Law and Ideal Solution (only one volatile

componet

)

Raoult’s

lawSlide9

Review

Ch. 14Raoult’s Law and Binary Ideal SolutionSlide10

Review

Ch. 14Gaseous phase

Partial pressure of component 1 Slide11

Review

Ch. 14Slide12

Review

Ch. 14

P-

x,y

diagramSlide13

Review

Ch. 14T-x,y diagramSlide14

Review

Ch. 14AzeotropesSlide15

Review

Ch. 14Slide16

Liquid-liquid equilibria

Basic concept of miscibilityMiscible –

e.g

: Toluene-benzene

Partially miscible –

e.g: water-phenolImmiscible – e.g: water-nitrobenzeneSlide17

Liquid-liquid equilibria

Basic concept

A + B

Liquid (bottom layer)

A + B

Liquid (upper layer)

In equilibrium condition

Partially miscible solutionSlide18

Liquid-liquid equilibria

Partially miscible liquid

P

= 2,

F= 1 the selection of temperature makes the compositions of the immiscible phases fixedP= 1, F = 2 (two liquids are fully mixed) both temperature and composition can be changedSlide19

Liquid-liquid equilibria

Partially miscible liquid

1. Add small amount of nitrobenzene to hexane at 290 K, it still dissolves completely,

P

= 1

2. Add more nitrobenzene to hexane and mixture of nitrobenzene-hexane becomes saturated, add more nitrobenzene, the mixture will become two phases (line 2-3).3. In point 3, the mixture will become saturated (more nitrobenzene)4. In point 4, the mixture will become one phase (hexane will dissolve in nitrobenzene)Slide20

Liquid-liquid equilibria

Representation of liquid liquid phase diagram

Point A - Mixture of 50 g hexane (0.59 mol C6H14) and 50 g nitrobenzene (0.41 mol C6H5NO2) was prepared at 290 K

A

There will be two phases solution with the composition at point 2 and point 3

x

N= 0.35 and xN= 0.83 (these arethe compositions of the two phasesSlide21

Liquid-liquid equilibria

Representation of liquid liquid phase diagram

Use Lever-Rule to determine the ratio of amount of each phase:

A

There is 7 times as much hexane-rich phase as there nitrobenzene-rich phase

If the mixture is heated to 292 K, we go into a single phase regionSlide22

Liquid-liquid equilibria

Representation of liquid liquid phase diagramSlide23

Liquid-liquid equilibria

Critical solution temperature

1. The upper critical solution temperature,

T

uc

2. The lower critical solution temperature, TlcSlide24

Liquid-liquid equilibria

Critical solution temperature

1. The upper critical solution temperature,

T

uc

The upper critical solution temperature, Tuc, is the highest temperature at which phase separation occurSlide25

Liquid-liquid equilibria

Critical solution temperature

2. The lower critical solution temperature,

T

uc

The lower critical solution temperature, Tlc, is the lowest temperature at which phase separation occurFor triethylamine and water, the system is partially miscible above Tlc, and single phase belowSlide26

Liquid-liquid equilibria

Critical solution temperature

Some systems have both

T

uc

and Tlc, with a famous example being nicotine in water, where Tuc= 210oC and Tlc= 61oCSlide27

Liquid-liquid equilibria

0

1

X

nicotine

Temperature ( oC )

X2

X

1

X

3

T

1

210

o

C

61

o

C

T

2

T

3

nicotine / water solution

nicotine saturated water rich phase in equilibrium with a water saturated nicotine rich phase

T

4

lower consulate temperature

we cool a nicotine water solution of composition X

2

from some temperature above the upper consulate temperature of 210

o

C.

At temperatures greater than T

1

the nicotine and water are miscible

When T

1

is reached water saturated nicotine rich phase just begins to form and is in equilibrium with the predominant nicotine saturated water rich phase

As the system is further cooled there will be two phase region. In the two phase region the relative amounts of the phases present are again given by the lever law, e.g. at T

2

we have:

n

X1

(X

2

- X

1

) = n

X3

(X

3

- X

2

)Slide28

Liquid-liquid equilibria

Distillation of partially miscible liquids

First case - the

T

uc

is lower than the azeotrope temperature Slide29

Liquid-liquid equilibria

Distillation of partially miscible liquids

a

1

initial composition and temperature –one phase

a2 the point where boiling begins and the vapor will have composition at b1When the distillate is cooled enough to cause condensation, a single phase first forms, represent by point b2

point b3 represents the overall composition once the temperature is lowered back to the starting temperatureSlide30

Liquid-liquid equilibria

Distillation of partially miscible liquids

Another case - the

T

uc

is higher than the azeotrope temperature Slide31

Liquid-liquid equilibria

Distillation of partially miscible liquids

a

1

initial composition and temperature –one phase

It will start boiling at point a2 with vapor having composition given by point b1This distillate will condense into a two phase liquid directly (b3).Slide32

Liquid-liquid equilibria

Distillation of partially miscible liquids

A system at e

1

forms two phases up to the boiling point at e

2condensing a vapor of composition e3gives a two-phase liquid of the same overall compositionAt e2, F = 0, their compositions and the temperature are fixed Slide33

Liquid-liquid equilibriaSlide34

Liquid-liquid equilibria

Distillation of immiscible liquidsImmiscible liquidsSlide35

Liquid-liquid equilibria

Distillation of immiscible liquidsImmiscible liquids

The total vapor pressures of liquids isSlide36

Liquid-liquid equilibria

Distillation of immiscible liquidsSlide37

Liquid-liquid equilibria

Distillation of immiscible liquidsExample: Aniline(1)-water(2) system, we want to distill 100 g of water from this mixture at 98.4°C under atmospheric condition

The mass of aniline that distills for each 100 g of waterSlide38

Liquid-liquid equilibria

System of three componentsCall Gibbs Phase Rule

P

= 1,

F

= 4 – T, P, x1, x2P = 2, F = 3 – T, P, x

1Slide39

Liquid-liquid equilibria

Ternary phase diagramHow to read it

100% C

100% A

100% BSlide40

Liquid-liquid equilibria

Ternary phase diagramTernary phase diagram for methyl isobutyl

ketone

+ acetone + water

Liquid-liquid phase separation occurs

Binodal / cloud point curve

Plait pointSlide41

Thank You !