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 1

H 3COOHCH

224 HCOOHCH

224

ddn

.....dndndndn

i

i

4

4

3

3

2

2

1

1

ddn

.....3

dn

1

dn

1

dn

1

dn

i

iHCOOHCH 224

Reaction Coordinate e

i0i0i

0

0

i0iii

i0ii

nn nn

nn

n

n

n

ny

nn

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

28

34y

28

1y

28

1y

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

224

H 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

11,i

1,i

1,4

1,4

1,3

1,3

1,2

1,2

1,1

1,1 ddn

.....dndndndn

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

1

dn

1

dn

1

dn

2224

224

jj,i

j,i

j,4

j,4

j,3

j,3

j,2

j,2

j,1

j,1d

dn.....

dndndndn

Reaction Coordinate e

ij,ij0i0i

jjj,10

jjj,10

jjj,i0i

ii

jjj,i0ii

nn nn

nn

n

n

n

ny

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

228

434y

228y

228

1y

228

21y

228

2y

22

24

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-1

T/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 oK298,fi

oK298 GG

DD oK298,fi

oK298 HH

2T

TR

H

dT

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-1

T/K

Multiple Reactions

Problems

Problems

Problems

Lagrange Multiplier for Complex Reaction

0aPˆn

nlnTRG

kikki

iofi

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