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Advanced Thermodynamics Note 12 Chemical-Reaction Equilibria Lecturer: 郭郭郭

Lecture 12

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  • Advanced Thermodynamics
    Note 12
    Chemical-Reaction Equilibria

    Lecturer:

  • Chemical reaction

    Both the rate and equilibrium conversion of a chemical reaction depend on the temperature, pressure, and composition of reactants.Although reaction rates are not susceptible to thermodynamic treatment, equilibrium conversions are.The purpose of this lecture is to determine the effect of temperature, pressure, and initial composition on the equilibrium conversions of chemical reactions.
  • A general chemical reaction:A differential change in the number of moles of a reacting species:

    Reaction coordinate, which characterizes the extent or degree to which a reaction has taken place.

    Reaction coordinate

  • For a system in which the following reaction occurs,

    assume there are present initially 2 mol CH4, 1 mol H2O, 1 mol CO and 4 mol H2. Determine expressions for the mole fractions yi as functions of .

  • Consider a vessel which initially contains only n0 mol of water vapor. If decomposition occurs according to the reaction,

    find expressions which relate the number of moles and the mole fraction of each chemical species to the reaction coordinate .

  • Multireaction

    Two or more independent reactions proceed simultaneouslyi,j : the stoichiometric number of species i in reaction j.the change of the moles of a species ni:

    total stoichiometric number:

    integration

    summation

  • Consider a system in which the following reactions occur,

    if there are present initially 2 mol CH4 and 3 mol H2O, determine expressions for the yi as functions of 1 and 2 .

    i

    CH4

    H2O

    CO

    CO2

    H2

    j

    j

    1

    -1

    -1

    1

    0

    3

    2

    2

    -1

    -2

    0

    1

    4

    2

  • Equilibrium criteria to chemical reactions

    is the single variable that characterizes the progress of the reactionthe total Gibbs energy at constant T and P is determined by if not in chemical equilibrium, any reaction leads to a decrease in the total Gibbs energy of the systemThe condition for equilibrium:the total Gibbs energy is a minimumIts differential is zero
  • Fig 13.1

  • Standard Gibbs energy change and the equilibrium constant

  • The fugacity of a species in solution:

    For pure species i in its standard state:

  • The equilibrium constant for the reaction, f(T)

    The standard Gibbs energy change of reaction, f(T)

    Other standard property changes of reaction :

  • For a chemical species in its standard state:

    summation

  • Readily calculated at any temperature from the standard heat of reaction and the standard Gibbs energy change of reaction at a reference temperature

  • Fig 13.2

  • Calculation the equilibrium constant for the vapor-phase hydration of ethylene at 145 and at 320 C from data given in App.c

    The heat capacity data:

    From Table C.4

    TK0K1K2K298.1529.3661129.366418.1529.3664.985x10-30.9861.443x10-1593.1529.3661.023x10-40.97942.942x10-3
  • Gas phase reaction:Ideal-gas state: Standard-state pressure Po of 1 bar

    An ideal solution:

    An ideal gas:

    f (T)

    f (P)

    f (composition)

  • Liquid phase reaction:

    Except at high pressures

    Ideal solution

    Law of mass action

  • Equilibrium conversions for single reactions

    Single reaction in a homogeneous system:assuming an ideal gas and the equilibrium constant is known:assuming an ideal solution and the equilibrium constant is known:the phase composition at equilibrium can be obtained
  • The water-gas-shift reaction, is carried out under the different sets of conditions described below. Calculate the fraction of steam reacted in each case. Assume the mixture behave as an ideal gas.

    (a) the reactant consists of 1 mol of H2O vapor and 1 mol of CO, T = 1100 K, P = 1 bar

    From Fig 13.2, K = 1

    (b) the same as (a) except that the pressure is 10 bar

    Since v = 0, the increase in pressure has no effect:

    (c) the same as (a) except that 2 mol of N2 is included in the reactants

    Since N2 does not take part in the reaction and serves as a diluent:

  • (d) the reactants are 2 mol of H2O and 1 mol of CO. other conditions are the same as (a)

    The fraction of steam that reacts is then 0.667 / 2 = 0.333

    (e) the reactants are 1 mol of H2O and 2 mol of CO. other conditions are the same as (a)

    The fraction of steam that reacts is then 0.667

    (f) the initial mixture consists of 1 mol of H2O, 1 mol of CO and 1 mol of CO2 . other conditions are the same as (a)

    The fraction of steam that reacts is then 0.333

  • (g) same as (a) except that the temperature is 1650 K

    From Fig 13.2, K = 0.316

    The reaction is exothermic, and conversion decreases with increasing temperature.

  • Estimate the maximum conversion of ethylene to ethanol by vapor phase hydration at 250C and 35 bars for an initial steam-to-ethylene ratio of 5.

    For a temperature of 250C, K = 10.02 x 10-3

    Assuming the reaction mixture is an ideal solution.

    Tc /K

    Pc /bar

    Tri

    Pri

    B0

    B1

    i

    C2H4

    282.3

    50.40

    0.087

    1.853

    0.694

    -0.074

    0.126

    0.977

    H2O

    647.1

    220.55

    0.345

    0.808

    0.159

    -0.511

    -0.281

    0.887

    EtOH

    513.9

    61.48

    0.645

    1.018

    0.569

    -0.327

    -0.021

    0.827

  • The equilibrium conversion is a function of temperature, pressure, and the steam-to-ethylene ratio in the feed:

    Fig 13.4

  • In a laboratory investigation, acetylene is catalytically hydrogenated to ethylene at 1120 C and 1 bar. If the feed is an equilmolar mixture of acetylene and hydrogen, what is the composition of the product stream at equilibrium?

    Ideal gas

  • Acetic acid is esterified in the liquid phase with ethanol at 100 C and atmospheric pressure to produce ethyl acetate and water according to the reaction:

    If initially there is 1 mol of each of acetic acid and ethanol, estimate the mole fraction of ethyl acetate in the reacting mixture at equilibrium.

    For the reaction at standard state (298 K):

    Assuming ideal solution:

  • The gas phase oxidation of SO2 to SO3 is carried out at a pressure of 1 bar with 20% excess air in an adiabatic reactor. Assuming that the reactants enter at 25C and that equilibrium is attained at the exit, determine the composition and temperature of the product stream from the reactor

    For the reaction at standard state (298 K):

    Assuming 1 mol of SO2 entering the reactor,

    O2: 0.5 x (1.2) = 0.6 mol entering

    N2: 0.6 x (79/12) = 2.257 mol entering

    In the product stream:

    SO2: 1 - e

    O2: 0.6 - 0.5e

    SO3: e

    N2: 2.257

    total moles: 3.857-0.5e

    Energy balance:

    The enthalpy change of the products at T

  • Assuming ideal gas:

    Assume T

    ln K

    T

    Converges at T = 855.7 K, e = 0.77

    ...

  • Reactions in heterogeneous systemsa criterion of vapor/liquid equilibrium, must be satisfied along with the equation of chemical-reaction equilibrium

    Estimate the compositions of the liquid and vapor phases when ethylene reacts with water to form ethanol at 200C and 34.5 bar, conditions which assure the presence of both liquid and vapor phases. The reaction vessel is maintained at 34.5 bar by connection to a source of ethylene at this pressure. Assume no other reactions.

    According to phase rule (see later): F = 2 (say, P, T)

    the material balance equations do not enter into the solution of this problem.

    Regarding the reaction occurring in the vapor phase:

    Assuming ideal gas :

  • Phase equilibrium:

    For vapor phase:

    For liquid phase:

    Ideal solution (vapor):

  • volatile

    Known values:

    P, T, , , , ,

  • Assume xEtOH

    xH2O

    yC2H4

    K

    check

    Converged at:

    Values of , are determined experimentally

    xi

    yi

    EtOH

    0.06

    0.180

    H2O

    0.94

    0.464

    C2H4

    0.00

    0.356

    =1

    =1

  • Phase rule and Duhems theorem for reacting systems

    For non-reacting systems phases and N chemical species:For reacting systemsPhase rule variables in each phase: temperature, pressure and N-1 mole fraction. Total number of these variable: 2 + (N-1) Phase-equilibrium equations: (-1) Nr independent chemical reactions at equilibrium within the system: r equationsF = [2+(N-1) ] - [(-1) N] [r] :With special constraints s:
  • Determine the number of degree of freedom F for each of the following systems:

    A system of two miscible non-reacting species which exists as an azeotrope in vapor/liquid equilibrium.A system prepared by partially decomposing CaCO3 into an evacuated space.A system prepared by partially decomposing NH4Cl into an evacuated space.A system consisting of the gases CO, CO2, H2, H2O, and CH4 in chemical equilibriumTwo non-reacting species in two phases

    With no azeotrope:

    With azeotrope (x1=y1, one constraint):

    Single reaction:

    Three chemical species and three phases:

    Single reaction:

    Three chemical species and two phases:

    One constraint: gas phase is equimolar

  • (d) 5 species, a single gas phase, and no special constraints:

    ???

    The formation reactions:

    Eliminating C

    Eliminating C

    Eliminating O2

    Eliminating O2

    r = 2

  • Duhems theorem

    For non-reacting system :For any closed system formed initially from given masses of particular chemical species, the equilibrium state is completely determined by specification of any two independent variables. For reacting system:A variable is introduced for each independent reaction: j A equilibrium relation can be written for each independent reaction
  • Multireaction equilibria

    A separate equilibrium constant is evaluated for each reaction:gas phase reaction

    Ideal gas

  • A feed stock of pure-n-butane is cracked at 750K and 1.2 bar to produce olefins. Only two reactions have favorable equilibrium conversions at these conditions:

    If these reactions reach equilibrium, what is the product composition?

    With a basis of 1 mol of n-butane feed:

    Assuming ideal gas:

  • A bed of coal 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 for temperature 1000, 1100, 1200, 1300, 1400, and 1500 K.

    The feed stream:

    1 mol C,O2 = (0.21)(2.38) = 0.5 mol,N2 = (0.79)(2.38) = 1.88 mol

    The formation reactions for the compounds are:

    K = ...

    Gf J/mol

    T (K)

    H2O

    CO

    CO2

    1000

    -192424

    -200240

    -395790

    1100

    -187000

    -209110

    -395960

    1200

    -181380

    -217830

    -396020

    1300

    -175720

    -226530

    -396080

    1400

    -170020

    -235130

    -396130

    1500

    -164310

    -243740

    -396160

  • Assuming ideal gases for the remaining species:

    With a basis of 1 mol of C feed:

    Carbon is a pure solid phase:

    Three equations and three unknowns can be solved.

  • Non- stoichiometric method

    Alternative method to solve chemical reaction equilibrium problemsbase on the fact that the total Gibbs energy of the system has it minimum valuethe basis for a general scheme of computer solution Find the set {ni} which minimizes Gt for specified T and P, subject to the constraints of the material balances.
  • Lagranges undetermined multiplier method

    The material balance on each element k :

    multiply the Lagrange multipliers

    summed over k

  • F (and Gt) minimum value?

    gas phase reaction

    pure ideal gas

  • Calculate the equilibrium compositions 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, there are present 2 mol of CH4 and 3 mol of H2O. Values of Gf at 1000 K of each species are given.

    Ideal gas:

    Element k

    C

    O

    H

    Ak = no. of atomic masses of k in the system

    2

    3

    14

    species

    aik = no. of atoms of k per molecule of i

    CH4

    1

    0

    4

    H2O

    0

    1

    2

    CO

    1

    1

    0

    CO2

    1

    2

    0

    H2

    0

    0

    2

  • For the 5 species:

    CH4 :

    ...

    5 equations

    For the 3 elements:

    C :

    H :

    O :

    3 equations

    1 equations

    Solve simultaneously

    ...

    ...

    4

    4

    3

    3

    2

    2

    1

    1

    +

    +

    +

    +

    A

    v

    A

    v

    A

    v

    A

    v

    e

    d

    v

    dn

    v

    dn

    v

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    =

    =

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    ...

    4

    4

    3

    3

    2

    2

    1

    1

    )

    ...,

    ,

    2

    ,

    1

    (

    N

    i

    d

    v

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    e

    )

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    ,

    2

    ,

    1

    (

    0

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    i

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    i

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    2

    H

    n

    j

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    i

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    mol

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    45792

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    o

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    P

    f

    =

    K

    P

    f

    i

    v

    o

    i

    i

    =

    P

    y

    f

    i

    i

    i

    f

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    (

    )

    K

    P

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    y

    o

    i

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    i

    i

    i

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    n

    i

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    =

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    g

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    i

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    i

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    f

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    RT

    dP

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    i

    n

    n

    (

    )

    1

    2

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    =

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    O

    H

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    H

    i

    v

    i

    y

    y

    y

    y

    y

    i

    2

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    CO

    y

    e

    -

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    2

    2

    e

    CO

    y

    e

    =

    2

    1

    2

    e

    O

    H

    y

    e

    -

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    2

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    H

    y

    e

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    5

    .

    0

    =

    e

    e

    3

    1

    e

    CO

    y

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    3

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    e

    CO

    y

    e

    =

    3

    2

    2

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    y

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    3

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    y

    e

    =

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    .

    0

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    e

    e

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    e

    CO

    y

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    3

    1

    2

    e

    O

    H

    y

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    -

    =

    3

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    CO

    y

    e

    +

    =

    333

    .

    0

    =

    e

    e

    316

    .

    0

    2

    2

    2

    =

    O

    H

    CO

    CO

    H

    y

    y

    y

    y

    36

    .

    0

    =

    e

    e

    1

    -

    =

    i

    i

    n

    n

    )

    10

    02

    .

    10

    (

    3

    2

    2

    4

    2

    4

    2

    -

    =

    o

    O

    H

    O

    H

    H

    C

    H

    C

    EtOH

    EtOH

    P

    P

    y

    y

    y

    f

    f

    f

    T

    c

    /K

    P

    c

    /bar

    T

    ri

    P

    ri

    B

    0

    B

    1

    i

    C

    2

    H

    4

    282.3

    50.40

    0.087

    1.853

    0.694

    -0.074

    0.126

    0.977

    H

    2

    O

    647.1

    220.55

    0.345

    0.808

    0.159

    -0.511

    -0.281

    0.887

    EtOH

    513.9

    61.48

    0.645

    1.018

    0.569

    -0.327

    -0.021

    0.827

    )

    10

    02

    .

    10

    (

    1

    35

    )

    887

    .

    0

    (

    )

    977

    .

    0

    (

    )

    827

    .

    0

    (

    3

    2

    4

    2

    2

    2

    4

    2

    4

    2

    -

    =

    =

    O

    H

    H

    C

    EtOH

    O

    H

    O

    H

    H

    C

    H

    C

    EtOH

    EtOH

    y

    y

    y

    y

    y

    y

    f

    f

    f

    e

    e

    H

    C

    y

    e

    e

    -

    -

    =

    6

    1

    4

    2

    e

    e

    O

    H

    y

    e

    e

    -

    -

    =

    6

    5

    2

    e

    e

    EtOH

    y

    e

    e

    -

    =

    6

    233

    .

    0

    =

    e

    e

    2

    2

    2

    2

    H

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    H

    C

    +

    4

    2

    2

    2

    2

    H

    C

    H

    C

    +

    4

    2

    2

    2

    2

    H

    C

    H

    H

    C

    +

    o

    II

    o

    I

    o

    G

    G

    G

    D

    +

    D

    =

    D

    II

    I

    K

    RT

    K

    RT

    K

    RT

    ln

    ln

    ln

    -

    -

    =

    -

    (

    )

    (

    )

    1

    10

    5

    .

    2

    10

    4

    6

    5

    =

    =

    =

    -

    II

    I

    K

    K

    K

    1

    2

    2

    2

    4

    2

    =

    H

    C

    H

    H

    C

    y

    y

    y

    e

    e

    H

    y

    e

    e

    -

    -

    =

    2

    1

    2

    e

    e

    H

    C

    y

    e

    e

    -

    -

    =

    2

    1

    2

    2

    e

    e

    H

    C

    y

    e

    e

    -

    =

    2

    4

    2

    293

    .

    0

    =

    e

    e

    414

    .

    0

    2

    2

    2

    =

    =

    H

    C

    H

    y

    y

    172

    .

    0

    4

    2

    =

    H

    C

    y

    O

    H

    H

    COOC

    CH

    OH

    H

    C

    COOH

    CH

    2

    5

    2

    3

    5

    2

    3

    +

    +

    2

    1

    e

    EtOH

    AcH

    x

    x

    e

    -

    =

    =

    e

    e

    v

    n

    v

    n

    n

    n

    x

    i

    i

    i

    i

    +

    +

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    0

    0

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    e

    O

    H

    EtAc

    x

    x

    e

    =

    =

    6879

    .

    0

    =

    e

    e

    344

    .

    0

    2

    /

    6879

    .

    0

    =

    =

    EtAc

    x

    J

    G

    J

    H

    o

    o

    4650

    3640

    298

    298

    -

    =

    D

    -

    =

    D

    8759

    .

    1

    15

    .

    298

    314

    .

    8

    4650

    ln

    298

    =

    =

    D

    -

    =

    RT

    G

    K

    o

    8586

    .

    4

    373

    =

    K

    K

    x

    x

    x

    x

    EtOH

    AcH

    O

    H

    EtAc

    =

    2

    3

    2

    2

    2

    1

    SO

    O

    SO

    +

    J

    G

    J

    H

    o

    o

    70866

    98890

    298

    298

    -

    =

    D

    -

    =

    D

    0

    298

    =

    D

    =

    D

    +

    D

    H

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    H

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    e

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    )

    15

    .

    298

    (

    )

    15

    .

    298

    (

    -

    =

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    =

    D

    T

    C

    n

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    C

    H

    i

    H

    o

    Pi

    i

    H

    o

    P

    o

    P

    15

    .

    298

    298

    +

    D

    -

    =

    H

    o

    P

    e

    o

    C

    H

    T

    e

    5

    .

    0

    =

    i

    i

    n

    n

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    e

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    5

    .

    0

    5

    .

    0

    6

    .

    0

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    .

    0

    857

    .

    3

    1

    e

    e

    e

    e

    (

    )

    IDCPH

    T

    IDCPS

    T

    K

    1

    4

    .

    11894

    3054

    .

    11

    ln

    -

    +

    +

    -

    =

    e

    e

    0062

    .

    0

    5

    .

    0

    857

    .

    3

    1

    2

    =

    -

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    =

    e

    e

    SO

    y

    e

    e

    )

    (

    5

    2

    )

    (

    2

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    (

    2

    2

    g

    g

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    OH

    H

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    H

    H

    C

    +

    o

    O

    H

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    C

    EtOH

    P

    f

    f

    f

    K

    2

    4

    2

    =

    bar

    P

    o

    1

    =

    K

    T

    15

    .

    473

    =

    031

    .

    0

    15

    .

    473

    =

    K

    K

    l

    i

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    i

    f

    f

    =

    o

    l

    l

    l

    o

    v

    v

    v

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    f

    f

    f

    P

    f

    f

    f

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    H

    H

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    EtOH

    O

    H

    H

    C

    EtOH

    2

    4

    2

    2

    4

    2

    =

    =

    P

    y

    f

    i

    i

    v

    i

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    l

    i

    i

    i

    l

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    (

    )

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    )

    o

    l

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    H

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    H

    C

    H

    C

    l

    EtOH

    EtOH

    EtOH

    P

    f

    x

    P

    y

    f

    x

    K

    2

    2

    2

    4

    2

    4

    2

    g

    f

    g

    =

    sat

    i

    sat

    i

    sat

    i

    l

    i

    P

    f

    f

    f

    =

    ~

    i

    i

    f

    f

    =

    (

    )

    (

    )

    o

    sat

    O

    H

    sat

    O

    H

    O

    H

    O

    H

    H

    C

    H

    C

    sat

    EtOH

    sat

    EtOH

    EtOH

    EtOH

    P

    P

    x

    P

    y

    P

    x

    K

    2

    2

    2

    2

    4

    2

    4

    2

    f

    g

    f

    f

    g

    =

    P

    P

    x

    y

    i

    sat

    i

    sat

    i

    i

    i

    i

    f

    f

    g

    =

    P

    P

    x

    P

    P

    x

    y

    O

    H

    sat

    O

    H

    sat

    O

    H

    O

    H

    O

    H

    EtOH

    sat

    EtOH

    sat

    EtOH

    EtOH

    EtOH

    H

    C

    2

    2

    2

    2

    2

    4

    2

    1

    f

    f

    g

    f

    f

    g

    -

    -

    =

    O

    H

    EtOH

    H

    C

    y

    y

    y

    2

    4

    2

    1

    -

    -

    =

    (

    )

    (

    )

    o

    sat

    O

    H

    sat

    O

    H

    O

    H

    O

    H

    H

    C

    H

    C

    sat

    EtOH

    sat

    EtOH

    EtOH

    EtOH

    P

    P

    x

    P

    y

    P

    x

    K

    2

    2

    2

    2

    4

    2

    4

    2

    f

    g

    f

    f

    g

    =

    4

    2

    2

    1

    H

    C

    EtOH

    O

    H

    x

    x

    x

    -

    -

    =

    (

    )

    (

    )

    O

    H

    O

    H

    H

    C

    EtOH

    EtOH

    x

    y

    x

    K

    2

    2

    4

    2

    0493

    .

    0

    g

    g

    =

    O

    H

    O

    H

    EtOH

    EtOH

    H

    C

    x

    x

    y

    2

    2

    4

    2

    493

    .

    0

    907

    .

    0

    1

    g

    g

    -

    -

    =

    sat

    O

    H

    2

    f

    sat

    EtOH

    f

    4

    2

    H

    C

    f

    sat

    EtOH

    P

    sat

    O

    H

    P

    2

    EtOH

    O

    H

    x

    x

    -

    =

    1

    2

    031

    .

    0

    15

    .

    473

    =

    K

    K

    x

    i

    y

    i

    EtOH

    0.06

    0.180

    H

    2

    O

    0.94

    0.464

    C

    2

    H

    4

    0.00

    0.356

    =1

    =1

    O

    H

    EtOH

    2

    g

    g

    N

    F

    +

    -

    =

    p

    2

    r

    N

    F

    -

    +

    -

    =

    p

    2

    s

    r

    N

    F

    -

    -

    +

    -

    =

    p

    2

    2

    0

    2

    2

    2

    2

    =

    -

    +

    -

    =

    -

    +

    -

    =

    r

    N

    F

    p

    1

    2

    =

    -

    -

    +

    -

    =

    s

    r

    N

    F

    p

    )

    (

    2

    )

    (

    )

    (

    3

    g

    s

    s

    CO

    CaO

    CaCO

    +

    )

    (

    2

    )

    (

    )

    (

    3

    g

    s

    s

    CO

    CaO

    CaCO

    1

    1

    3

    3

    2

    2

    =

    -

    +

    -

    =

    -

    +

    -

    =

    r

    N

    F

    p

    )

    (

    )

    (

    3

    )

    (

    4

    g

    g

    s

    HCl

    NH

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    NH

    +

    1

    1

    1

    3

    2

    2

    2

    =

    -

    -

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    =

    -

    -

    +

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    =

    s

    r

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    p

    )

    (

    )

    (

    3

    )

    (

    4

    g

    g

    s

    HCl

    NH

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    +

    s

    r

    N

    F

    -

    -

    +

    -

    =

    p

    2

    CO

    O

    C

    +

    2

    2

    1

    2

    2

    CO

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    C

    +

    O

    H

    O

    H

    2

    2

    2

    2

    1

    +

    4

    2

    2

    CH

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    C

    +

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    2

    2

    1

    CO

    O

    CO

    +

    2

    2

    2

    4

    2

    CO

    H

    O

    CH

    +

    +

    2

    2

    2

    4

    2

    CO

    H

    O

    CH

    +

    +

    O

    H

    CO

    H

    CO

    2

    2

    2

    +

    +

    2

    2

    2

    4

    4

    2

    CO

    H

    O

    H

    CH

    +

    +

    4

    0

    2

    5

    1

    2

    2

    =

    -

    -

    +

    -

    =

    -

    -

    +

    -

    =

    s

    r

    N

    F

    p

    2

    ]

    )

    1

    [(

    ]

    )

    1

    (

    2

    [

    =

    +

    -

    -

    +

    -

    +

    =

    N

    N

    N

    F

    p

    p

    p

    2

    1

    1

    ]

    )

    1

    [(

    ]

    )

    1

    (

    2

    [

    =

    -

    +

    +

    -

    -

    +

    -

    +

    =

    N

    N

    N

    F

    p

    p

    p

    j

    i

    v

    o

    i

    i

    K

    f

    f

    j

    i

    =

    ,

    j

    i

    v

    o

    i

    K

    P

    f

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    i

    =

    ,

    (

    )

    j

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    y

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    j

    i

    n

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    ,

    6

    2

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    2

    10

    4

    H

    C

    H

    C

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    +

    4

    6

    3

    10

    4

    CH

    H

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    C

    +

    II

    I

    II

    I

    H

    C

    y

    e

    e

    e

    e

    +

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    =

    1

    1

    10

    4

    II

    I

    I

    H

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    H

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    y

    y

    e

    e

    e

    +

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    =

    1

    6

    2

    4

    2

    II

    I

    II

    CH

    H

    C

    y

    y

    e

    e

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    +

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    =

    =

    1

    4

    6

    3

    (

    )

    j

    o

    i

    v

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    P

    y

    j

    j

    i

    n

    -

    =

    ,

    I

    o

    H

    C

    H

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    H

    C

    K

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    P

    y

    y

    y

    1

    10

    4

    6

    2

    4

    2

    -

    =

    II

    o

    H

    C

    CH

    H

    C

    K

    P

    P

    y

    y

    y

    1

    10

    4

    4

    6

    3

    -

    =

    1068

    .

    0

    =

    I

    e

    8914

    .

    0

    =

    II

    e

    001

    .

    0

    10

    4

    =

    H

    C

    y

    0534

    .

    0

    6

    2

    4

    2

    =

    =

    H

    C

    H

    C

    y

    y

    4461

    .

    0

    4

    6

    3

    =

    =

    CH

    H

    C

    y

    y

    O

    H

    O

    H

    2

    2

    2

    2

    1

    +

    CO

    O

    C

    +

    2

    2

    1

    2

    2

    CO

    O

    C

    +

    G

    f

    J/mol

    T (K)

    H

    2

    O

    CO

    CO

    2

    1000

    -192424

    -200240

    -395790

    1100

    -187000

    -209110

    -395960

    1200

    -181380

    -217830

    -396020

    1300

    -175720

    -226530

    -396080

    1400

    -170020

    -235130

    -396130

    1500

    -164310

    -243740

    -396160

    2

    1

    2

    2

    2

    -

    =

    o

    H

    O

    O

    H

    I

    P

    P

    y

    y

    y

    K

    2

    1

    2

    =

    o

    O

    CO

    II

    P

    P

    y

    y

    K

    2

    2

    O

    CO

    III

    y

    y

    K

    =

    (

    )

    2

    38

    .

    3

    2

    I

    II

    I

    H

    y

    e

    e

    e

    -

    +

    -

    =

    (

    )

    2

    38

    .

    3

    I

    II

    II

    CO

    y

    e

    e

    e

    -

    +

    =

    (

    )

    (

    )

    2

    38

    .

    3

    1

    2

    1

    2

    I

    II

    III

    II

    I

    O

    y

    e

    e

    e

    e

    e

    -

    +

    -

    -

    -

    =

    (

    )

    2

    38

    .

    3

    1

    2

    I

    II

    I

    O

    H

    y

    e

    e

    e

    -

    +

    +

    =

    (

    )

    2

    38

    .

    3

    2

    I

    II

    III

    CO

    y

    e

    e

    e

    -

    +

    =

    (

    )

    2

    38

    .

    3

    88

    .

    1

    2

    I

    II

    N

    y

    e

    e

    -

    +

    =

    1

    )

    1

    (@

    )

    20

    (@

    =

    bar

    f

    bar

    f

    f

    f

    o

    C

    C

    o

    C

    C

    (

    )

    (

    )

    N

    P

    T

    t

    n

    n

    n

    n

    g

    G

    ...

    ,

    ,

    ,

    3

    2

    1

    ,

    =

    k

    i

    ik

    i

    A

    a

    n

    =

    0

    =

    -

    k

    i

    ik

    i

    k

    A

    a

    n

    l

    0

    =

    -

    k

    k

    i

    ik

    i

    k

    A

    a

    n

    l

    -

    +

    =

    k

    k

    i

    ik

    i

    k

    t

    A

    a

    n

    G

    F

    l

    )

    ,...,

    2

    ,

    1

    (

    0

    ,

    ,

    ,

    ,

    N

    i

    a

    n

    G

    n

    F

    k

    ik

    k

    n

    P

    T

    i

    t

    n

    P

    T

    i

    j

    j

    =

    =

    +

    =

    l

    )

    ,...,

    2

    ,

    1

    (

    0

    N

    i

    a

    k

    ik

    k

    i

    =

    =

    +

    l

    m

    +

    =

    o

    i

    i

    o

    i

    i

    f

    f

    RT

    G

    ln

    m

    +

    =

    o

    i

    o

    i

    i

    P

    f

    RT

    G

    ln

    m

    +

    D

    =

    o

    i

    i

    o

    fi

    i

    P

    P

    y

    RT

    G

    f

    m

    ln

    )

    ,...,

    2

    ,

    1

    (

    0

    ln

    N

    i

    a

    P

    P

    y

    RT

    G

    k

    ik

    k

    o

    i

    i

    o

    fi

    =

    =

    +

    +

    D

    l

    f

    Element

    k

    C

    O

    H

    A

    k

    = no. of atomic masses of

    k

    in the system

    2

    3

    14

    species

    a

    ik

    = no. of atoms of

    k

    per molecule of

    i

    CH

    4

    1

    0

    4

    H

    2

    O

    0

    1

    2

    CO

    1

    1

    0

    CO

    2

    1

    2

    0

    H

    2

    0

    0

    2

    1

    =

    i

    f

    1

    =

    o

    P

    P

    )

    ,...,

    2

    ,

    1

    (

    0

    ln

    N

    i

    a

    RT

    n

    n

    RT

    G

    k

    ik

    k

    i

    i

    i

    o

    fi

    =

    =

    +

    +

    D

    l

    0

    4

    ln

    19720

    4

    =

    +

    +

    +

    RT

    RT

    n

    n

    RT

    H

    C

    i

    i

    CH

    l

    l

    2

    2

    4

    =

    +

    +

    CO

    CO

    CH

    n

    n

    n

    14

    2

    2

    4

    2

    2

    4

    =

    +

    +

    H

    O

    H

    CH

    n

    n

    n

    3

    2

    2

    2

    =

    +

    +

    CO

    CO

    O

    H

    n

    n

    n

    2

    2

    2

    4

    H

    CO

    CO

    O

    H

    CH

    i

    i

    n

    n

    n

    n

    n

    n

    +

    +

    +

    +

    =