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Homework Help: Thermo VLE problem with mathcad

  1. Apr 20, 2009 #1
    1. The problem statement, all variables and given/known data

    For acetone (1) methanol (2) system based on Wilson equation make the following calculations:

    (a) BUBL P: T=60oC, =0.3
    (b) DEW P: T=60oC, =0.3
    (c) PT-flash: T=60oC, P=1/2 (Pbubble+ Pdew), z1=0.3
    (d) If an azeotrope exist at 60oC, find Paz and x1az=y1az .
    The table on page 362 lists parameter values for the Antoine Equation. Parameters for Wilson equations are : a12=504.31 , a21=196.75 .

    2. Relevant equations

    Antoine eq - calculate Psat
    Rackett eq - molar volume (liquid)
    Wilson Eq - gamma
    modified Rault's Law

    3. The attempt at a solution

    The problem is not the actual solution of the problem - it is getting mathcad to produce the answers (all homework is required to be done in Mathcad for this class). See the http://www.megaupload.com/?d=YOX2IEX9" [Broken]

    So, after the above calculations, I need to find 3 things - bubble pressure, y1 and y2. I have 3 equations - modified Rault (1 for each species) and y1 + y2=1. I put these in a solve block, tell mathcad to find the answers and... it turns red. The solve block is on the second page.

    Can anyone point out what I'm doing wrong here? I run into trouble all the time with these Find functions. So far in this class I'm spending much more time trying to figure out Mathcad than I am Thermo.
    Last edited by a moderator: May 4, 2017
  2. jcsd
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