[gibbw]

Hello all,

So my issue is that I am attempting to control the molar composition of a gaseous atmosphere above a mixture of two solvents.  The idea is to have a small enclosed space 1 square foot that has a small heating "cup" that I can put a binary mixture of solvents in.  I would control the molar composition of the gas using the initial liquid molar ratio and heat. 
So I have two issues: 
First, the problem of mixed solvents and deviation from Raoults Law is usually talked about in terms of distillation with one of the solvents are above it's boiling point.  I don't necessarily want to go above the boiling point but would still need to account for the non-ideallity of the mixture.  So am I fundamentally wrong about this, I.E. does the non-ideality only happen in the regime of distillation?  It seems to me that the interactions that govern this still exist under boiling point.  How can I predict the gas molar composition at temperatures below boiling?
Second, I have been looking for resources that have these Temperature-composition plots (such as http://www.ddbst.com/ddb-vle.html), however, obviously these show the point at which one solvent is at or above boiling. Does anyone know of any resources or data bases that have information below b.p.?

I feel that this is a fundamental misunderstanding on my part and most likely conflating two or more ideas.  I just don't know what I am conflating.

Any help is greatly appreciated!!