# Thermo VLE problem with mathcad

1. Apr 20, 2009

### adam_cheme

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
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