8/9/2019 06 the Properties of Mixtures

1/54

The properties of mixtures

8/9/2019 06 the Properties of Mixtures

2/54

Chapter 6 The properties of mixtures

6.1 The thermodynamic description of mixtures

6.1.1 Partial molar properties

6.1.2 Spontaneous mixing

6.1.3 Ideal solutions

6.1.4 Ideal dilute solutions

6.1. !eal solutions" acti#ities

6.2 Colligati#e properties

6.2.6 The modification of $oiling and free%ing points

6.2.& 'smosis

6.3 Phase diagrams of mixtures

6.3.( )ixtures of #olatile li*uids

6.3.+ ,i*uid-li*uid phase diagrams

6.3.1 ,i*uid-solid phase diagrams

6.3.11 The /ernst distri$ution la0

8/9/2019 06 the Properties of Mixtures

3/54

The partial molar volumes ofwater and ethanol at 25C.

8/9/2019 06 the Properties of Mixtures

4/54

partial molar volume

8/9/2019 06 the Properties of Mixtures

5/54

t 2C the density of a per cent $y mass

ethanol50ater solution is .+14 g cm-3. i#en that the

partial molar #olume of 0ater in the solution is 1&.4 cm3mol-1 0hat is the partial molar #olume of the ethanol7

8/9/2019 06 the Properties of Mixtures

6/54

partial molar Gibbs energy, GJ

8/9/2019 06 the Properties of Mixtures

7/54

ressure dependen!e of G

chf1

G = H TS

dG = dH TdS SdT = Vdp - SdT

= V

For liquid or solid,G= Vp

For vapor,G= Vdp= nRT(1/p)dp=nRT ln(pf/pi)

Gm= RT ln(pf/pi)

Chap.

8/9/2019 06 the Properties of Mixtures

8/54

8/9/2019 06 the Properties of Mixtures

9/54

8/9/2019 06 the Properties of Mixtures

10/54

The i$$s energy of mixing of t0o perfect gases of t0o

li*uids that form an ideal solution.

8/9/2019 06 the Properties of Mixtures

11/54

Chap. 4

The entropy change with isothermal expansion

ch4f4

2

1

2 2 2

1 1 1

2 2

1 1

1

1

ln ln

S dqT

p nRdw dV dV T T V

V pnR nR

V p

=

= = =

= =

8/9/2019 06 the Properties of Mixtures

12/54

The entropy of mixing of t0o perfect gases of t0o li*uids

that form an ideal solution.

8/9/2019 06 the Properties of Mixtures

13/54

!aoult8s la0"

p2x

2p29

8/9/2019 06 the Properties of Mixtures

14/54

8/9/2019 06 the Properties of Mixtures

15/54

8/9/2019 06 the Properties of Mixtures

16/54

8/9/2019 06 the Properties of Mixtures

17/54

Figure 6.6 The partial vapour pressures o the twocomponents o an ideal !inary mixture areproportional to the mole ractions o the componentsin the liquid. The total pressure o the vapour is thesum o the two partial vapour pressures.

The partial #apour pressure of

a su$stance in a li*uid mixture

is proportional to its molefraction in the mixture and its

#apour pressure 0hen pure"

"aoult#s law$for Ideal solution, esp. for solvent

http://ebooks.bfwpub.com/elements5e/sections/figurehttp://ebooks.bfwpub.com/elements5e/sections/figure

8/9/2019 06 the Properties of Mixtures

18/54

chemical potential o a solvent % present in solutionat a mole ractionx%is

8/9/2019 06 the Properties of Mixtures

19/54

t e*uili$rium chemical potential of any

gi#en component is same e#ery0here.

8/9/2019 06 the Properties of Mixtures

20/54

&enry#s law,for ideal solutes

8/9/2019 06 the Properties of Mixtures

21/54

The experimental partial vapour pressureso a mixture o trichloromethane, '&'l

('), and propanone, '&''&(acetone,

%),

8/9/2019 06 the Properties of Mixtures

22/54

8/9/2019 06 the Properties of Mixtures

23/54

The chemical potential of the solute has its

standard #alue 0hen the molar concentration of

the solute is 1 mol dm 3 ;that is

8/9/2019 06 the Properties of Mixtures

24/54

G = H TS

dG = dH TdS SdT = Vdp SdT

d = Vmdp SmdT

*

*+RTlnxA

-Sm(s)T

-Sm(l)TRTlnxA

{Sm(l) - Sm(s) }T = RTlnxA

s= * Sm(s) dT

l= * Sm(l) dT + RT lnxA

8/9/2019 06 the Properties of Mixtures

25/54

*+RTlnxA

*

Sm(g)T

Sm(l)T

{Sm(l) - Sm(g) }T = RTlnxA

{Sm(l) - Sm(g) }T = RTlnxA

g= * Sm(g) dT

l= * Sm(l) dT + RT lnxA

8/9/2019 06 the Properties of Mixtures

26/54

8/9/2019 06 the Properties of Mixtures

27/54

8/9/2019 06 the Properties of Mixtures

28/54

A(xA=1, p) A(xA, p+)A(xA=1, p) =A(xA, p+)

8/9/2019 06 the Properties of Mixtures

29/54

8/9/2019 06 the Properties of Mixtures

30/54

8/9/2019 06 the Properties of Mixtures

31/54

8/9/2019 06 the Properties of Mixtures

32/54

pA =xApA*=apA

*

pB =xBpB * = (1-a)pB *

a'= pA /(pA +pB) = apA*/(apA

*+(1-a)pB

*) apA

*5;pB*= a;pA

*-pB*

8/9/2019 06 the Properties of Mixtures

33/54

a'= pA /(pA +pB)= apA

*/(apA*+(1-a)pB

*)

apA *5;pB *= a;pA *-pB *

8/9/2019 06 the Properties of Mixtures

34/54

8/9/2019 06 the Properties of Mixtures

35/54

8/9/2019 06 the Properties of Mixtures

36/54

8/9/2019 06 the Properties of Mixtures

37/54

low-boiling(positive) azeotrope

repeated distillation can ne#er produce a

distillate that is richer in constituent > than

the a%eotrope

%eotrope

?

8/9/2019 06 the Properties of Mixtures

38/54

8/9/2019 06 the Properties of Mixtures

39/54

high-boiling(negative) azeotrope ; <

?

%eotrope

8/9/2019 06 the Properties of Mixtures

40/54

8/9/2019 06 the Properties of Mixtures

41/54

8/9/2019 06 the Properties of Mixtures

42/54

8/9/2019 06 the Properties of Mixtures

43/54

8/9/2019 06 the Properties of Mixtures

44/54

8/9/2019 06 the Properties of Mixtures

45/54

8/9/2019 06 the Properties of Mixtures

46/54

8/9/2019 06 the Properties of Mixtures

47/54

8/9/2019 06 the Properties of Mixtures

48/54

8/9/2019 06 the Properties of Mixtures

49/54

8/9/2019 06 the Properties of Mixtures

50/54

8/9/2019 06 the Properties of Mixtures

51/54

8/9/2019 06 the Properties of Mixtures

52/54

8/9/2019 06 the Properties of Mixtures

53/54

8/9/2019 06 the Properties of Mixtures

54/54