ITK-234 Termodinamika Teknik Kimia 2

Chemical Equilibria

Dicky Dermawanwww.dickydermawan.net78.net

dickydermawan@gmail.com

Reaction Coordinate e......AA......AA 33332211

3 1 1 1H 3COOHCH

224 HCOOHCH

224

e

ddn

.....dndndndn

i

i

4

4

3

3

2

2

1

1

e

ddn

.....3

dn

1dn

1

dn

1

dn

i

iHCOOHCH 224

Reaction Coordinate e

eee

e

i0i0i

0

0

i0iii

i0ii

nn nn

nnn

nnn

y

nn

If, initially there are 2 mol CH4, 1 mol H2O, 1 mol CO, and 4 mol H2:

ee

e

e

ee

e

e

e

eeee

2834

y 28

1y

281

y 28

2y

28n n n nn

23111

34n 1n 1n 2n

84112nn nn n

4n 1n 1n 2n

224

224

224

224

224

224

HCOOHCH

HCOOHCH

HCOOHCH

HCOOHCH

0,H0,CO0,OH0,CH0

0,H0,CO0,OH0,CH

Reaction Coordinate

Reaction Coordinate: Multiple Reactions

.......................................................................

......AA......AA 2,3232,3232,2222,121

......AA......AA j,3j3j,3j3j,2j2j,1j1

......AA......AA 1,3131,3131,2121,111

2224

224H 4COOH 2CH

H 3COOHCH

j v CH4 v H2O v CO v CO2 v H2 νj

1 -1 -1 1 0 3 22 -1 -2 0 1 4 2

Reaction Coordinate: Multiple Reactions

22,i

2,i

2,4

2,4

2,3

2,3

2,2

2,2

2,1

2,1 ddn

.....dndndndn

e

11,i

1,i

1,4

1,4

1,3

1,3

1,2

1,2

1,1

1,1 ddn

.....dndndndn

e

22,i

2,i2,H2,CO2,OH2,CH

11,i

1,i1,H1,CO1,OH1,CH

ddn

.....4

dn

1

dn

2

dn

1

dn

ddn

.....3

dn

1dn

1

dn

1

dn

2224

224

e

e

jj,i

j,i

j,4

j,4

j,3

j,3

j,2

j,2

j,1

j,1 ddn

.....dndndndn

e

Reaction Coordinate e

e

e

e

e

ij,ij0i0i

jjj,10

jjj,10

jjj,i0i

ii

jjj,i0ii

nn nn

nn

n

n

nn

y

nn

If, initially there are 2 mol CH4, 1 mol H2O, 1 mol CO, and 4 mol H2:

21

21H

21

2CO

21

1CO

21

21OH

21

21CH

228434

y 228

y

228

1y

22821

y 228

2y

22

24

eeee

ee

e

eee

ee

ee

eeee

Reaction Coordinate

Reaction Coordinate & Equilibrium Condition

0dG P,Tt

H2O CO CO2

1000 -192420 -200240 -3957901100 -187000 -209110 -3959601200 -181380 -217830 -2960201300 -175720 -226530 -3960801400 -170020 -235130 -3961301500 -164310 -243740 -396160

DGfo/J.mol-1T/K

Reaction Coordinate & Equilibrium Condition (Cont’)

Method of Equilibrium Constant

ffffK3

H1

CO1

OH1

CH 224

TR

Gexp)a(K

0ii

ii

i)f(K iFor gases:

224 H 3COOHCH

For ideal gases:

PKKK y

PKK y

Method of Equilibrium

Constant

Problems

Problem Hint: Different Way Leads to The Same Results

Problems

Calculation of Equilibrium Constant DD o

K298,fio

K298 GG

DD oK298,fi

oK298 HH

2T

TR

HdT

Klnd

D

298o

K298 Kln298RG D

dTCHHT

298

op

o298T DDD

D opi

op CC

dTTR

HKlnd

2T

Kln

Kln

T

K298

D

)K298(o

fGD

)K298(o

fGD

)K298(o

fGD

)K298(o

fGD

)K298(o

fHD

)K298(o

fHD

)K298(o

fHD

)K298(o

fHD

Heat Capacity Data - Gases

Heat Capacity Data - Gases

Heat Capacity Data - Solid

Heat Capacity Data - Liquid

Problems

Problems

Problems

Problems

Problems

Problems

Problems

Problems

Problems

Multiple ReactionsA bed of coal (assume pure carbon) in a coal

gasifier is fed with steam and air and produce a gas stream containing H2, CO, O2, H2O, CO2, and N2. If the feed to the gasifier consists of 1 mol of steam and 2.38 mol of air, calculate the equilibrium composition of the gas stream at P = 20 bar.

H2O CO CO2

1000 -192420 -200240 -3957901100 -187000 -209110 -3959601200 -181380 -217830 -2960201300 -175720 -226530 -3960801400 -170020 -235130 -3961301500 -164310 -243740 -396160

DGfo/J.mol-1T/K

Multiple Reactions

Problems

Problems

Problems

Lagrange Multiplier for Complex Reaction

0aPˆnn

lnTRGk

ikkiio

fi

D

i

kiki AanFirst Step: Atomic Balances

#2 Step:

No. of eqn = no. of involved atom

No. of eqn = no. of species involved

Use Computer to Solve All The Equation Simultaneously.

ProblemCalculate the equilibrium composition at 1000 K

and 1 bar of a gas-phase system containing the species CH4, H2O, CO, CO2, and H2. In the initial unreacted state ther are present 2 mol of CH4 and 3 mol of H2O. Assume ideal gases.

At 1000 K:

1-oCO f

1-oCO f

1-oOH f

-1oCH f

molJ 395790G

molJ 200240G

molJ 192420G

molJ 19720G

2

2

4

D

D

D

D