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Heat Capacity Ethyl Acetate

  1. Apr 17, 2007 #1
    I need the heat capacity Ethyl Acetate as a function of temperature. I've seen books that give heat capacity as a function of functional group, but the problem is they are only at one temperature. What I basically need is some coefficients that would fit into the equation Cp= A +BT+CT^2+DT^-2. For this capacity, I can approximate Ethyl Acetate as a liquid operating from 298.15K to approximately 373.15K (I know this isn't realistic because the boiling point of ethyl acetate is around 350.25K).

    I have already checked Perry's Handbook and other various thermochemical fluid properties texts, but I still can't find anything.

    Thanks for any assistance you can give me.
     
  2. jcsd
  3. Apr 17, 2007 #2

    Q_Goest

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    Hi sicjeff,
    Can you be more specific? What pressure and what temperature range to you need?
     
  4. Apr 17, 2007 #3
    Thanks for responding. I am running my reaction at temperature ranges of 298.15-373.15 K and my pressure will be in the area of 1 bar.
     
  5. Apr 17, 2007 #4

    Q_Goest

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    Hi sicjeff,
    I have a computerized database that has these values in it, but it doesn't give equations. You can print out values and then do a curve fit though. Also, the database is in English units, so you'll need to convert to metric.

    I'm assuming you mean a pressure of 1 bara, not 1 barg. If you need it for 1 barg, I can simply change the value and give you the same spreadsheet if you'd like.

    At 1 bara, it shows a saturation temperature of roughly 170.85 F which is where the disjoint is in the spreadsheet.

    Hope that helps.
     

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  6. Apr 17, 2007 #5

    Q_Goest

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    sicjeff,
    I'm not sure what you're using this for, but I suspect you're working out the equation so you can integrate it and determine the change of state between two temperatures, such as by adding X amount of heat.

    You might consider simply using enthalpy and internal energy directly instead. They're generally much easier to work with IMO. Coming up with an equation for U or H as a function of temperature is just as easy as Cp.
     
  7. Apr 17, 2007 #6
    Actually I'm doing reaction equillibria with the extended van't Hoff equation. Thank you so very much for your assistance.

    Can I get the name of the database you are using if you don't mind?
     
  8. Apr 18, 2007 #7
    If we say Cp=α+βT+γT^2 and Cp=a +bT+cT^-2, combined, we get your equation Cp=A+BT+CT^2+DT^-2. (Intro. to Chemical Engineering, Pavia, pp 127)

    Since I couldn’t find coefficients for your derived formula, I looked up the coefficients of Cp=α+βT+γT^2. Basically Coefficient α = 7.235; Coefficient β= 0.4072; Coefficient γ =2.092E-04. Units of Cp are in kJ/kg-mol , Temperature in Kelvins.
    http://www.cheric.org/kdb/kdb/hcprop/showcoef.php?cmpid=1059&prop=CPG

    You see that there is another coefficient (Coefficient D), if Cp=α+βT+γT^2 was extended to another higher power.
     
    Last edited: Apr 18, 2007
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