Trying to find partial pressure using partition functions

Forum|Forum|15 years ago
April 14, 2011
13 replies
7394 views

Hi everyone,

I am new to the Mathad world when it comes to the nonlinear solvers for system of equations. I would appreciate any help that I can get

I am trying to find partial pressures for an equilibrium equation of state model. I am running into trouble as to how I can get each of the partial pressures as a function of my temperature. I am attaching the Mathcad file so that you can see what I mean. I have doubled check my stuff but I am unsure of how to proceed. It keeps saying that "initial guess must consist of numbers and matrices".

Anybody care to get me out of my mess I have created?

Thanks,

Addison

1_Final-Project_No-Ionization-xmcd.zip

Other

Best answer by RichardJ

You can't take the derivative w.r.t. T because it's not a function of T. To make it a function of T also requires some changes earlier in the worksheet. See the highlighted regions.

As an aside, if you have to multiply by m^3 to be able t take the log, that might indicate a problem. It depends on where the formula comes from. If it is an empirical formula, this can happen. If it is a formula derived from the physics, it will never happen. If it's derived from the physics and the log of the quantity has any physical meaning then the quantity must be dimensionless to begin with.

A

AlanStevens

19-Tanzanite

The attached might help a little, but doesn't solve all your problems!

Alan

1_Final-Project_No-Ionization2-xmcd.zip

R

RichardJ

19-Tanzanite

You need to turn the solve block into a function.

1_Final-Project_No-Ionization-mcd.zip

M

msu12181

Author

1-Visitor

I appreciate the help in correcting the mess I created. I wish there is was a way I could get all the partial pressures to calculate out of the entire temp range instead of limiting it to the first couple.

Thanks again for all your help.

Addison