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Calculating pressure

Discussion in 'Bottling/Kegging' started by geranimo, May 27, 2017.

 

  1. #1
    geranimo

    Member

    Posted May 27, 2017
    I'm trying to figure out the pressure calculations.

    Say I want 2.5 volumes of co2, which is ~60L of co2 at 293K at 100kPa. Using PV = nRT I get 2.64mol of co2 dissolved in a keg. Next I use Henry's law with Kh = 0.035 and I get 55 PSI of pressure at equilibrium, which I find not very likely. Anyone knows where my calculations fails?
     
  2. #2
    hvjackson

    Well-Known Member  

    Posted May 28, 2017
    Your calculation is failing because the ideal gas law is not applicable to this situation where you have a mixture of liquid and gas. The solubility of CO2 in water is not determined by the ideal gas law.
     
  3. #3
    geranimo

    Member

    Posted May 28, 2017
    No. I use the ideal gas law to get the number of moles of co2 dissolved with the definition of what is a volume of co2.
     
  4. #4
    RPh_Guy

    Bringing Sour Back

    Posted May 28, 2017
    At 20C should be 27.6 psi (using online calculator). Can't help with the math, sorry.
     
    Last edited: May 28, 2017
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