lecture 1 - phase equilibrium

7/24/2019 Lecture 1 - Phase Equilibrium

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8.1 - Single Component System

TOPIC 8 : PHASE EQUIBLIBRIA

8. - T!o Component System 8." - Collig#ti$e P%ope%ties

8.1 - SI&'LE8.1 - SI&'LE

CO(PO&E&T S)STE(CO(PO&E&T S)STE( O*+e,ti$e :At te en o/ tis lesson st0ents so0l *e #*le to:

#2 3e/ine p#se #n ,omponent.

*2 3e/ine t%iple point #n ,%iti,#l point.

,2 S4et, #n e5pl#in te p#se i#g%#m o/ HO

#n CO.

E5pl#in te #nom#lo0s *e#$io0% o/ HO.

2 3es,%i*e te ,#nges in p#se !it %espe,t toi. tempe%#t0%e #t ,onst#nt p%ess0%e2

ii. p%ess0%e #t ,onst#nt tempe%#t0%e2.

P#se 6 Component

T%iple Point 6 C%iti,#l Point

P#se 3i#g%#m HO

P#se 3i#g%#m CO


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8.1 - SI&'LE8.1 - SI&'LE

CO(PO&E&T S)STE(CO(PO&E&T S)STE( 3e/initions

PHASE :The phases of a system are parts of it which are

separated by a distinct boundary, such as solid, liquid

and gas.Homogenous part of a system which is chemically and

physically uniform.

E5#mple

Rel#tionsip


P#se 3i#g%#m HO

P#se 3i#g%#m CO

P#se 6 Component

3e/inition

E5e%,ise


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A two-phase system is one containing either

- a gas and a solid

- a gas and a liquid

- a solid and a liquid

- a solid and a solid

- two immiscible liquids

A three-phase system is one containing either

- a solid, a liquid, and a gas

- two immiscible liquids and a gas


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3e/initions

CO(PO&E&T :CO(PO&E&T :

A component is a chemically independent constituent of a system. The

number of components in a system is the minimum number of independentspecies necessary to define the composition of all the phases present in the

system.

The number of components in a phase system is the minimum number of

chemical entities needed to define all the phase of the system


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8.1 - SI&'LE8.1 - SI&'LE

CO(PO&E&T S)STE(CO(PO&E&T S)STE( E5#mple :

E5#mple

Rel#tionsip


P#se 3i#g%#m HO

P#se 3i#g%#m CO

P#se 6 Component

3e/inition


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8.1 - SI&'LE8.1 - SI&'LE

CO(PO&E&T S)STE(CO(PO&E&T S)STE( Rel#tionsip *et!een System7 P#se 6 Component

System P C 3es,%iption

Mixtureof gases

!ependtypes of

gases

"ases are well mixed.#e cannot see

the boundary betweenthe gases.

Two liquids!o not mix$oil-water%

& & #e can see the boundarybetween the two liquid,

Two liquidswell mixed

$alcohol-water%

& #e cannot seethe boundary of

the solution.

E5#mple

Rel#tionsip


P#se 3i#g%#m HO

P#se 3i#g%#m CO

P#se 6 Component

3e/inition


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8.1 - SI&'LE8.1 - SI&'LE


PHASE 3IA'RA( :A graphical plot of pressure 's temperature that shows

the conditions at which a substance exists as a solid,

liquid or gas in a one component system.

(hows the conditions under which equilibrium exists

between the different states of matter.

A typical phase diagram has three regions ) solid, liquidand gas. *ach of these region is separated by their

boundary lines $i% solid+gas $ii% solid liquid and $iii% liquid

gas.


P#se 3i#g%#m HO

P#se 3i#g%#m CO

P#se 6 Component


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8.1 - SI&'LE8.1 - SI&'LE


CRITICAL POI&T :At this point and abo'e, it is not possible to liquefy a

gas howe'er great the pressure is. ndeed the term

'apour should only be used below the critical point, asit implies that it is possible to form a liquid.

TRIPLE POI&T :TRIPLE POI&T :

Triple point is an unique point at which the three linesrepresenting the solid+liquid, liquid+'apour and

solid+'apour equilibriums. t represents the conditions at

which all the three phases can co-exist in a stable

manner and each is at equilibrium with the other two.


P#se 3i#g%#m HO

P#se 3i#g%#m CO

P#se 6 Component


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8.1 - SI&'LE8.1 - SI&'LE


CRITICAL TE(PERATURE :

The highest temperature at which a gas can

be liquefied.

CRITICAL PRESSURE :

The pressure required to liquefy a gas at the

critical temperature.


P#se 3i#g%#m HO

P#se 3i#g%#m CO

P#se 6 Component


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8.1 - SI&'LE8.1 - SI&'LE

CO(PO&E&T S)STE(CO(PO&E&T S)STE( P#se 3i#g%#m o/ HO

C%iti,#l Point

T%iple Point

1oC

1 #tm

oC Tempe%#t0%e oC2

P%e

ss0%e1#tm2


P#se 3i#g%#m HO

P#se 3i#g%#m CO

C0%$e 3es,%iption

E5pl#n#tion

Anom#lo0s Be#$io%

P#se 6 Component


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8.1 - SI&'LE8.1 - SI&'LE

CO(PO&E&T S)STE(CO(PO&E&T S)STE(

C0%$es in P#se 3i#g%#m o/ HO

C%iti,#l Point

T%iple Point

1oC

1 #tm

oC

Tempe%#t0%e oC2

P%ess0%e1#tm2

T-C: Rep%esents te $#%i#tion o/T-C: Rep%esents te $#%i#tion o/ *oiling*oilingtempe%#t0%e !it pess0%etempe%#t0%e !it pess0%e

T

A

B C

T-B: Rep%esents te $#%i#tion o/T-B: Rep%esents te $#%i#tion o/ meltingmeltingtempe%#t0%e !it pess0%etempe%#t0%e !it pess0%e

T-A: Rep%esents te $#%i#tion o/T-A: Rep%esents te $#%i#tion o/ s0*lim#tions0*lim#tiontempe%#t0%e !ittempe%#t0%e !it

pess0%epess0%e


P#se 3i#g%#m HO

P#se 3i#g%#m CO

C0%$e 3es,%iption

E5pl#n#tion

Anom#lo0s Be#$io%

P#se 6 Component


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8.1 - SI&'LE8.1 - SI&'LE

CO(PO&E&T S)STE(CO(PO&E&T S)STE( E5pl#n#tionAt lo! tempe%#t0%es #n #tmospe%i, p%ess0%e7 teAt lo! tempe%#t0%es #n #tmospe%i, p%ess0%e7 test#*le p#se is test#*le p#se is te soli i,e2.soli i,e2.

At 1 #tm7 te tempe%#t0%e #t !i, i,e #n !#te% #%e #tAt 1 #tm7 te tempe%#t0%e #t !i, i,e #n !#te% #%e #t

e90ili*%i0m7 is ,#lle tee90ili*%i0m7 is ,#lle te melting pointmelting point C 7 ;".1< =2.C 7 ;".1< =2.

Te line sep#%#tes te soli #n li90i p#ses. As tisTe line sep#%#tes te soli #n li90i p#ses. As tisline is not $e%ti,#l7 te t%#nsition /%om soli to li90iline is not $e%ti,#l7 te t%#nsition /%om soli to li90i

t#4es pl#,e #t i//e%ent tempe%#t0%es 0ne% i//e%entt#4es pl#,e #t i//e%ent tempe%#t0%es 0ne% i//e%ent

p%ess0%es.p%ess0%es.

At tempe%#t0%es *et!een At tempe%#t0%es *et!een C #n 1C #n 1C 0ne% 1C 0ne% 1

#tmospe%i, p%ess0%e7 te st#*le p#se is li90i !#te%.#tmospe%i, p%ess0%e7 te st#*le p#se is li90i !#te%.

At 1At 1C7 te line %ep%esenting te e90ili*%i0m *et!eenC7 te line %ep%esenting te e90ili*%i0m *et!een

li90i #n g#s is %e#,e #n te tempe%#t0%e #t !i,li90i #n g#s is %e#,e #n te tempe%#t0%e #t !i,

*oiling t#4es pl#,e 0ne% #tmospe%i, p%ess0%e is te*oiling t#4es pl#,e 0ne% #tmospe%i, p%ess0%e is te

*oiling point.*oiling point.Te *oiling point $#%ies #s te p%ess0%eTe *oiling point $#%ies #s te p%ess0%e

'aries.'aries.


P#se 3i#g%#m HO

P#se 3i#g%#m CO

C0%$e 3es,%iption

E5pl#n#tion

Anom#lo0s Be#$io%

P#se 6 Component


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8.1 - SI&'LE8.1 - SI&'LE

CO(PO&E&T S)STE(CO(PO&E&T S)STE( Anom#lo0s Be#$io% o/ HOThe phase diagram for water is not typical, the meltingThe phase diagram for water is not typical, the melting

temperature line , T-/ ,temperature line , T-/ , slopes to te le/tslopes to te le/t i.e. the meltingi.e. the melting

temperature decreases with pressure.temperature decreases with pressure.

This is connected with the fact thatThis is connected with the fact that ice is less dense thanice is less dense thanwater, while most solids are denser than their liquids.water, while most solids are denser than their liquids.

TheThe melting ,0%$emelting ,0%$eoror /0sion ,0%$e/0sion ,0%$eof ice + water is 'eryof ice + water is 'ery

special. t has a negati'e slope due to the fact that)special. t has a negati'e slope due to the fact that)

when ice melts, the molar volume decreases. Icewhen ice melts, the molar volume decreases. Ice

actually melt at lower temperature, higher pressure.actually melt at lower temperature, higher pressure.


P#se 3i#g%#m HO

P#se 3i#g%#m CO

C0%$e 3es,%iption

E5pl#n#tion

Anom#lo0s Be#$io%

P#se 6 Component


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8.1 - SI&'LE8.1 - SI&'LE

CO(PO&E&T S)STE(CO(PO&E&T S)STE( P#se 3i#g%#m o/ CO

T%iple Point

C%iti,#l Point

Tempe%#t0%e oC2

P%e

ss0%e1#tm2

C0%$e 3es,%iption

E5pl#n#tion


P#se 3i#g%#m HO

P#se 3i#g%#m CO

P#se 6 Component


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T%iple Point

C%iti,#l oint

8.1 - SI&'LE8.1 - SI&'LE


C0%$es in P#se 3i#g%#m o/ CO

P%e

ss0%e1#tm2

T

A

B C

Tempe%#t0%e oC2

T-C: Rep%esents te $#%i#tion o/T-C: Rep%esents te $#%i#tion o/ *oiling*oilingtempe%#t0%e !it p%ess0%etempe%#t0%e !it p%ess0%e

T-B: Rep%esents te $#%i#tion o/T-B: Rep%esents te $#%i#tion o/ meltingmeltingtempe%#t0%e !it pess0%etempe%#t0%e !it pess0%e

T-A: Rep%esents te $#%i#tion o/T-A: Rep%esents te $#%i#tion o/ s0*lim#tions0*lim#tiontempe%#t0%e !ittempe%#t0%e !it

p%ess0%ep%ess0%e

C0%$e 3es,%iption

E5pl#n#tion


P#se 3i#g%#m HO

P#se 3i#g%#m CO

P#se 6 Component


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8.1 - SI&'LE8.1 - SI&'LE

CO(PO&E&T S)STE(CO(PO&E&T S)STE( E5pl#in#tionThe phase diagram of carbon dioxide is moreThe phase diagram of carbon dioxide is more typi,#ltypi,#l,,showing ashowing a rightward slopingrightward slopingmelting temperature line.melting temperature line.

T%iple pointT%iple pointfor carbon dioxide is -0123 $ &4.5 6 % and 0.&for carbon dioxide is -0123 $ &4.5 6 % and 0.&

atm $ 04 78a %. The triple point is abo'e atmosphericatm $ 04 78a %. The triple point is abo'e atmospheric

pressure, so that at atmospheric pressure carbon dioxidepressure, so that at atmospheric pressure carbon dioxidesublimes, so dry ice, which is solid carbon dioxide, changessublimes, so dry ice, which is solid carbon dioxide, changes

directly from solid to gas.directly from solid to gas.

At this pressure, the liquid phase is not stable, the solidAt this pressure, the liquid phase is not stable, the solid

simply sublimes. Thus solid carbon dioxide is calledsimply sublimes. Thus solid carbon dioxide is called %y i,e%y i,e,,

because it does not go through a liquid state in its phasebecause it does not go through a liquid state in its phasetransition at room pressure.transition at room pressure.

The critical temperature for carbon dioxide is 9.:3, andThe critical temperature for carbon dioxide is 9.:3, and

the critical pressure is 19 atm. Abo'e the critical temperature,the critical pressure is 19 atm. Abo'e the critical temperature,

the fluid is called super-critical fluid.the fluid is called super-critical fluid.

C0%$e 3es,%iption

E5pl#n#tion


P#se 3i#g%#m HO

P#se 3i#g%#m CO

P#se 6 Component


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. !etermine the stable phase of 3arbon !ioxide ata% ;.10 atm and -4; o3

b% 0.0; atm and -1; o3

&. #hat is the physical state of water under each of the following

conditionsO8. - T>O


O*+e,ti$e :

/2 3e/ine #@eot%opi, mi5t0%e.

3ete%mine te ,omposition o/ #@eot%opi, mi5t0%e

/%om # *oiling point-,omposition i#g%#m.

g2 E5pl#in te p%in,iples in$ol$e in simple #n/%#,tion#l istill#tions o/ # *in#%y mi5t0%e.

2 3ete%mine te istill#te #n %esi0e o/ #

istill#tion /%om te *oiling point-,omposition i#g%#m.

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

1


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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( (is,i*ility

(ISCIBLE:

Two liquids are considered >miscible> or

mixable if sha7ing them together results in a

single liquid phase , with no meniscus 'isible

between layers of liquids.

Miscible refers to the property of 'ariousliquids that allows them to be mixed together.

*xample ) Methanol ? #aterMethanol ? #ater

(is,i*ility

(is,i*le

P#%ti#lly (is,i*le

Immis,i*le

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Ie#l Sol0tion


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8. - T>O8. - T>O


PARTIALL)PARTIALL) (ISCIBLE::

#hen one liquid partially dissol'es in the

other, the result is two solutions appearingas two layers. These two liquids are

considered to be partially miscible

*xample ) Hexanol ? #aterHexanol ? #ater

(is,i*ility

(is,i*le

P#%ti#lly (is,i*le

Immis,i*le

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion


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8. - T>O8. - T>O


I(I((ISCIBLE::

Two liquids are considered >immiscible> or

unmixable if sha7ing equal 'olumes of theliquids together results in a meniscus 'isible

between two layers of liquid, the 'olumes of

the liquid layers are the same as the 'olumes

of liquids orginally added to the mixture.

mmiscible refers to the property of 'arious

liquids that if they cannot be mixed together.

*xample ) @il ? #ater@il ? #ater

(is,i*ility

(is,i*le

P#%ti#lly (is,i*le

Immis,i*le

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Ie#l Sol0tion


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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( P%ope%ties O/ #n ie#l Sol0tion

A solution containing a mixture of liquid A and liquid /

is ideal solution if ,

the three different intermolecular forces A-A, /-/and A-/, are of the same type and comparable in

strengthand expect the molecules to intermingle

randomly into a solution. there is no energy changein the formation of the

solution , HsolutionB ;.

the 'olume of the solution is the sum of the

'olumes of the two liquids A and /, CsolutionB ;

@beys the Daoults law.

8actualB 8 measured$calculated%

The measured 'apour pressureof the solution isthe same as that predicted by the Daoults Eaw.

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

3i#g%#m


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8. - T>O8. - T>O


#po0% p%ess0%e 6 *oiling point i#g%#m

o/ #n ie#l Sol0tion(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

3i#g%#m


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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( 3e/inition

R#o0ltDs l#!states that the 'apor pressure of each

component in an ideal solution is dependent on the

'apor pressure of the indi'idual component and the

mole fraction of the component present in the solution.

@nce the components ha'e reached equilibrium in the

solution, the total 'apor pressure of the solution is)

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

C#l,0l#tion

E5#mple Q0estion


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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( C#l,0l#tion

The partial pressure of a sol'ent o'er a solution, PA, is gi'en

by the 'apour pressure of the pure sol'ent, 8oAtimes the mole

fraction of the sol'ent in the solution, FA)

PABFA8oA

n a solution containing only one solute, AF 1 G B, where

Bis the mole fraction of the solute. The abo'e equation can

be rewritten as G

PA F 1 G B2 PoA

PA

F Po

A

G B

PoA

Po G P F P F Po

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

C#l,0l#tion

E5#mple Q0estion

1"


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8. - T>O8. - T>O


Sol0tions t#t ,ont#in mo%e t#n one $ol#tile ,omponents

n many solutions such as benene and carbon

tetrachloride, both solute and sol'ent ha'e appreciabletendencies to undergo e'aporation.

n this case, the 'apour will contain both solute and

sol'ent molecules, and the 'apour pressure of the

solution will be the sum of the partial pressures exertedby each component.

The partial pressure of any component abo'e such a

mixture is also gi'en by Daoults Eaw.

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

C#l,0l#tion

E5#mple Q0estion

1"


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8. - T>O8. - T>O


Sol0tions t#t ,ont#in mo%e t#n one $ol#tile ,omponents

Thus, the partial pressure of component A , 8Ais gi'en by )

PA F APOAwhere )

8A B the 'apour pressure of pure A

FA B the mole fraction of A in the solution

(imilarly , the partial pressure of component / , 8/is )

PBF BPOB

where )

8/B the 'apour pressure of pure /

F/B the mole fraction of / in the solution

Iinally , the total 'apour pressure of a mixture of A and / is gi'en by

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

C#l,0l#tion

E5#mple Q0estion

1"


29/73




8. - T>O8. - T>O


C#l,0l#ting te #po0% P%ess0%e o/ # Sol0tion o/

t!o $ol#tile ,omponents

E5#mple :

A mi5t0%e ,ont#ining


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8. - T>O8. - T>O


C#l,0l#ting te #po0% P%ess0%e o/ # Sol0tion o/

t!o ol#tile Components

Sol0tion : /y using Daoults Eaw,

Jo of moles ) component A, 33l5 B ;.9&0 mol 33l5component /, 3H3l9B ;.5K mol 3H3l9

Mole fractions )

CCl B ;.9&0 B ;.591

$;.9&0 L ;.5K%

CHCl B ;.5K B ;.049

$;.9&0 L ;.5K%

8artial pressure of each component abo'e the solution )

PCClF CClPCCl B $;.591%$91 torr% B 9K torr

PCHClF CHClPCHCl B $;.049%$0&4 torr% B &K4 torr

Total 'apour pressure )F B L

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

C#l,0l#tion

E5#mple Q0estion


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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( &on-Ie#l sol0tion

Actually, 'ery few mixtures really obey

Daoults law. sually, the measured 'apour

pressure of the solution is either larger orsmaller than Daoults law.

f the 'apour pressure of the solution is larger

than Daoults Eaw, the solution will shows

positi$e e$i#tion

f the 'apour pressure of the solution

issmaller than Daoults Eaw, the solution will

shows neg#ti$e e$i#tion

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Positi$e 3e$i#tion

&eg#ti$e 3e$i#tion

O C S Q


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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( &on-Ie#l sol0tion : Positi$e 3e$i#tion

Composition-$#po0% p%ess0%ecur'e for a solutions that

shows positi'e de'iations from Daoults law

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Positi$e 3e$i#tion

&eg#ti$e 3e$i#tion

TOPIC 8 PHASE EQUIBLIBRIA


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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( &on-Ie#l sol0tion : Positi$e 3e$i#tion

Composition-$#po0% *oiling tempe%#t0%e i#g%#m /o% #

sol0tions t#t so!s positi$e e$i#tions /%om R#o0lt?s

l#!

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Positi$e 3e$i#tion

&eg#ti$e 3e$i#tion



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8. - T>O8. - T>O


&on-Ie#l sol0tion : Positi$e 3e$i#tion

#hen te #tt%#,ti$e /o%,es *et!een te sol0te #n

sol$ent mole,0les #%e !e#4e% t#n tose *et!een sol0te

mole,0lesor between sol'ent molecules, $A-A , /-/ N A-/%

neither the solute nor sol'ent particles are held as tightly in

the solution as they are in the pure substances.

The escaping tendency of each is therefore greater in the

solution than in the solute or sol'ent alone.

As a result, the partial pressures of both of them o'er the

solution are greater than that predicted by Daoults law.

Therefore, te sol0tion #s # l#%ge% $#po0% p%ess0%ethan

expected and exhibit a positi'e de'iation from Daoults law.

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Positi$e 3e$i#tion

&eg#ti$e 3e$i#tion



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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( &on-Ie#l sol0tion : &eg#ti$e 3e$i#tion

Composition-$#po0% p%ess0%ecur'e for a solution that

shows negati'e de'iations from Daoults law

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Positi$e 3e$i#tion

&eg#ti$e 3e$i#tion



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8. - T>O8. - T>O


Composition-$#po0% *oiling tempe%#t0%e i#g%#m /o% #

sol0tion t#t so! neg#ti$e e$i#tions /%om R#o0lt?s l#!

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Positi$e 3e$i#tion

&eg#ti$e 3e$i#tion



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8. - T>O8. - T>O


The opposite effect is produced when the solute-sol'ent

attractions are larger than the solute-solute and sol'ent-

sol'ent attractions A-B M A-A 7 B-B2.

*ach substance is held more tightly in the presence of eachother than in their pure liquids.

As a result, their partial pressures o'er the solution are less

than Daoults law would predict and their solutions show

neg#ti$e e$i#tions.

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Positi$e 3e$i#tion

&eg#ti$e 3e$i#tion



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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( Ie#l Sol0tion &on-Ie#l Sol0tion

Positi$e e$i#tion &eg#ti$e e$i#tion

S0mm#%y o/ sol0tion p%ope%ties

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion



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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( A@eot%ope :

An aeotrope is a mixture with the s#me te

,omposition o/ # $#po0% #n li90iand has

,onst#nt *oiling pointand ,#nnot *e

sep#%#te *y istill#tion.

A solution that shows positi$e e$i#tionsfrom

Daoults law, exhibits a minim0m-*oiling

#@eot%opeand m#5im0m-$#po0% p%ess0%e

#@eot%ope.

A solution that shows neg#ti$e e$i#tions

from Daoults law, exhibits a m#5im0m-*oiling

#@eot%opeand minim0m-$#po0% p%ess0%e

#@eot%ope.

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion



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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( 3istill#tion

A technique used for the separation of

components of a solution by boiling the

solution and then condensing its 'apour.

(imple distillation

Iractional distillation

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Simple istill#tion

N%#,tion#l istill#tion

3istill#tion *in#%y mi5t0%e

A@eot%opi, mi5t0%e



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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( Simple 3istill#tion

(imple distillation is a procedure by which two

liquids with different boiling points can be

separated .

(imple distillation is effecti'e only when

separating a 'olatile liquid from a non'olatile

substance or when separating two liquids that

differ in boiling point by 0; degrees or more.

(imple distillation is carried out without any

column pac7ing, n theory, simple distillation

in'ol'es as few as one theoretical plate .

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Simple istill#tion



A@eot%opi, mi5t0%e



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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( Simple 3istill#tion App#%#t0s(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Simple istill#tion



A@eot%opi, mi5t0%e



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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( N%#,tion#l 3istill#tion

Iractional distillation is a method to separatemixtures of liquids with boiling points that are

close to each other by repeated simple

distillation process.

n fractional distillation, the 'apors formedfrom the boiling mixture rise into thefractionating column where they condense on

the columnOs pac7ing.

As 'apors continue to rise through thecolumn, the liquid that has condensed will

re'aporie.

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Simple istill#tion



A@eot%opi, mi5t0%e



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8. - T>O8. - T>O

CO(PO&E&T S)STE(CO(PO&E&T S)STE( N%#,tion#l 3istill#tion App#%#t0s(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Simple istill#tion



A@eot%opi, mi5t0%e



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8. - T>O8. - T>O


N%#,tion#l istill#tion o/ *in#%y mi5t0%e A 6 B2

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Simple istill#tion



A@eot%opi, mi5t0%e



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N%#,tion#l istill#tion o/ *in#%y mi5t0%e A 6 B2

A fractionating column produces the effect of many

successi'e boiling and condensation cycles

automatically.The column sies ha'e a large surface area. The

liquid mixture boils and the 'apour rises up thecolumn.As the temperature drops, the 'apour condenses,

the liquid $richer in A% drops bac7 into the boiling flas7

and the 'apour $richer in /% mo'es up the column.

This happens many times as the 'apour rises up thetube.A long enough column will result in a 'apour of pure

/ at the top of the column and e'entually pure A left

in the boiling flas7.

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Simple istill#tion



A@eot%opi, mi5t0%e



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CO(PO&E&T S)STE(CO(PO&E&T S)STE( Composition o/ #@eot%opi, mi5t0%e

Te%e #%e some sol0tions t#t e5i*it $e%y l#%ge

e$i#tions /%om ie#lity.

(olutions exhibit positi'e de'iationsfrom Daoults law

(olutions exhibit negati'e de'iations

from Daoults law

As # %es0lt7 tey ,#nnot *e tot#lly sep#%#te into

tei% ,omponents e$en *y /%#,tion#l istill#tion.

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Simple istill#tion



A@eot%opi, mi5t0%e



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100

78.5

100% !#te%100% et#nol

8. - T>O8. - T>O


Sol0tions e5i*it positi$e e$i#tions

/%om R#o0lt?s l#!

These solutions ha'e a maximum in the 'apour pressure

cur'e and hence a minimum in the boiling point. !iagram

such a solution has minim0m-*oiling #@eot%ope.

Te *oiling point i#g%#m /o% !#te%-et#nol mi5t0%e

A@eot%opi, Composition

!#te%: .


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N%#,tion#l 3istill#tion et#nolG!#te% mi5t0%e

*thanol-water mixtures $obtained by fermentation of

sugar for example%, are rich in water.

Iractional distillation is able to concentrate the alcohol

to, at best, aeotropic composition of approximately

K0P by 'olume of ethanol.

@nce this composition has been achie'ed, the liquid

and 'apour ha'e the same composition, and noadditional fractionation ta7es place.

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Simple istill#tion



A@eot%opi, mi5t0%e



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78.5

100

8. - T>O8. - T>O


Sol0tions e5i*it neg#ti$e e$i#tions

/%om R#o0lt?s l#!

These solution ha'e a minimum in the 'apour pressure cur'e

and hence a maximum in the boiling point diagram. A solution

with such a maximum boiling point is called a m#5im0m-

*oiling point #@eot%ope.

Te *oiling point i#g%#m /o% nit%i, #,i-!#te% mi5t0%es

100% water 100% HNO3

Tem

pe%#t0%e

A@eot%opi, Composition$9.=P water and 4=.&P HJ@9%

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Simple istill#tion



A@eot%opi, mi5t0%e



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N%#,tion#l istil#tion nit%i, #,iG!#te% mi5t0%e

Iractional distillation is able to concentrate the nitric

acid. Irom the diagram, this aeotropic mixture can be

separating them into, at best, one pure component plus

a solution ha'ing the maximum boiling point $aeotropic

composition%.

Iractional distillation is able to concentrate the nitric

acid.

(is,i*ility

Ie#l Sol0tion

R#o0lt?s L#!

&on-ie#l Sol0tion

A@eot%ope

3istil#tion

Simple istill#tion



A@eot%opi, mi5t0%e



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8." - COLLI'ATIE8." - COLLI'ATIE

PROPERTIESPROPERTIES O*+e,ti$e :At te en o/ tis lesson st0ents so0l *e #*le to:

#2 3e/ine ,ollig#ti$e p%ope%ties.

*2 3es,%i*e te ,ollig#ti$e p%ope%ties o/ # sol0tion:

i. lo!e%ing o/ $#po0% p%ess0%e

ii. *oiling point ele$#tion

iii. /%ee@ing point ep%ession

i$. osmoti, p%ess0%e

,2 Pe%/o%m ,#l,0l#tions on ,ollig#ti$e p%ope%ties o/# non-ele,t%olyte sol0tion ,ont#ining non-$ol#tile

sol0tes.

Collig#ti$e p%ope%ties



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8roperties of solutions which depend on the

number of molecules present and not on the

7ind of molecules.

Iour colligati'e properties are )

. Capour pressure lowering

&. Ireeing point depression9. /oiling point ele'ation

5. @smotic pressure


#po0% p%ess0%e lo!e%ing

N%ee@ing point ep%ession

Boiling point ele$#tion

Osmoti, p%ess0%e


PROPERTIESPROPERTIES



54/73


Q


Te e//e,t o/ # non$ol#tile sol0te on te p#se

i#g%#m /o% !#te%.

#hen a solute is added to pure sol'ent, the mole fraction

decreases. Addition of a solute at constant T and 8 lowers the

sol'ent chemical potential.





Osmoti, p%ess0%e





55/73


Q



The change in 'apor pressure where the solute is

less 'olatile than the sol'ent is regulated by

DaoultOs law, which states that the pressure is

equal to the mole fraction of the sol'ent times the'apor pressure of pure sol'ent) 8BFsol'entQ8:.

The change in the 'apor pressure occurs when a

solute is added to a sol'ent.

f a non'olatile solute $one that has no tendency

to escape from a solution% is dissol'ed in a liquid

sol'ent, the 'apour pressure of the sol'ent is

lowered.





Osmoti, p%ess0%e





56/73

8.1 - Single Component System 8. - T!o Component System 8." - Collig#ti$e P%ope%ties


#hen a solute is added to the sol'ent, some of the solute

molecules occupy the space near the surface of the liquid, as

shown. #hen a solute is dissol'ed in a sol'ent, the number of

sol'ent molecules near the surface decreases, and the 'apor

pressure of the sol'ent decreases.

t decreases the rate at which the sol'ent molecules in the liquid

can escape into the gas phase. As a result, the 'apor pressure

of the sol'ent escaping from a solution should be smaller than

the 'apor pressure of the pure sol'ent.

P Po





Osmoti, p%ess0%e





57/73


C#l,0l#tion $#po0% p%ess0%e lo!e%ing

APBX=A

P-A

P

APBX-A

P=A

P

A)P

BX-(1=

AP

1=BX+AX

solventP

solventX=

solutionP

ABA PXP =





Osmoti, p%ess0%e





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C#l,0l#tion $#po0% p%ess0%e lo!e%ing

The 'apour pressure of pure water at &4o3 is

&0.& torr. #hat is the 'apour pressure of a

solution which contains &;.; g glucose,

34H&@4in 1; g water

lecture 1 - phase equilibrium

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