Equilibrio Quimico Problema 13.4 Smith And Van Ness

| 21.Mayo.2012 |
| UNIVERSIDAD AUTONOMA DE SAN LUIS POTOSI FACULTAD DE CIENCIAS QUIMICAS TERMODINAMICA II
PAULINA ROCHA SANCHEZ
|

[CHEMICAL EQUILIBRIUM CALCULATIONS. PROBLEM ASSIGNED: 13.4]|
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Problem:
13.4 Consider the water-gas-shift reaction:

At high temperatures and low to moderate pressures thereacting species form an ideal gas mixture. Application of the summability equation to Eq. (11.26) yield:

When the Gibbs energies of the elements in their standard states are set equal to zero, for eachspecies Gi=∆G°fi, and then:
A

At thebeginning of Sec. 13.2 we noted that Eq. (14.64) is a criterion of equilibrium. Applied to the water-gas-shift reaction with the understanding that T and P are constant, this equation becomes:

Here,however, dn/dε=0 . The equilibrium criterion therefore becomes:
B

Once the yi are eliminated in favor of ε, Eq. (A) relates G to ε. Data for ∆G°fi for the compounds of interest are given with Ex.13.13. For a temperature of 1000 K (the reaction is unaffected by P) and for a feed of 1 mol H2 and 1 mol CO2:
(a) Determine the equilibrium value of ε by the application of Eq. (B).
(b) Plot Gvs. ε , indicating the location of the equilibrium value of determined in (a).

Solution:

n 0 | n 0 | - | - |
-ε | -ε | +ε | +ε |
n 0 -ε | n 0 -ε | +ε | +ε |Species | ν | nj 0 | ε | nj | yj |
H2(g) | -1 | 1 | -ε | 1-ε | (1-ε)/2 |
CO2(g) | -1 | 1 | -ε | 1-ε | (1-ε)/2 |
H2O(g) | 1 | 0 | +ε | +ε | ε/2 |
CO(g) | 1 | 0 | +ε | +ε | ε/2 |
| Σ=0 |...