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Dissociation constant as function of T,p.

  1. Jan 8, 2015 #1
    1. The problem statement, all variables and given/known data
    For given general reaction 2A<->A2 the affinity constant is known k(T)=1.7 10-4 mol/cm3 (t=18 C) Find dissociation (constant) level in normal pressure.
    2. Relevant equations
    So i solved it - found the general solution for dissociation constant.
    alpha=1/(sqrt(1+4k))
    Now i have some quaestions,So first of all where do i factor in the pressure?
    Like this alpha=1/(sqrt(1+4 p k(T))) and if yes what kind of units would be correct to use?

    More importantly If i need to calculate the dissociation constant for the same reaction but only in different temperature, what should i do then ?

    Looking forward to hearing from you guys!

    3. The attempt at a solution
     
  2. jcsd
  3. Jan 8, 2015 #2

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    PTotal = ∑Pi, where Pi are the partial pressures of all species present. Conversely, mole fraction x PTotal is the partial pressure of a selected species. Units obvious enough to you with that information?
     
  4. Jan 8, 2015 #3
    yes, i think units are clear now ,thanks :)

    But still,not clear what to do with different temperature i know that k(t)=Exp(a),where a is function form chemical potential maybe its possible to calculate in this way. but its seems irrational.
     
  5. Jan 10, 2015 #4

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    You need enthalpy and heat capacity data (or estimates) for the reaction to examine temperature dependence.
     
  6. Jan 10, 2015 #5
    I got it!
    it is possible to get relation by using reaction heat
    Q=RT^2 d/dT (ln K)
     
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