4 replies to this topic

[wjrhee]

does anybody know how to calculate the boiling point of a solution?
let's say a solution of 10 mols of ethanol and 90 mols of water at 25 psi?

i hear there's two ways. one assuming that it's an ideal solution, and one assuming that it's non ideal.

does anybody know how to calculate the boiling point of a solution?
let's say a solution of 10 mols of ethanol and 90 mols of water at 25 psi?

i hear there's two ways. one assuming that it's an ideal solution, and one assuming that it's non ideal.

Start here:

Boiling Point Elevation

Keep it simple.

[MrShorty]

Yes, there are a few different ways to calculate the boiling point (perhaps more accurately termed bubble point in this case) of a solution. Ideal case for compounds like ethanol and water usually refers to Raoult's law. Non-ideal solutions vary in form and complexity. For you, the simplest non-ideal solution might be to look at incorporating activity coefficients into Raoult's Law (so called modified Raoult's law). I'd recommend you start by figuring out how to use Raoult's law (internet is full of explanations of Raoult's law), solve the problem as if it were ideal, and go from there.

[wjrhee]

oh yeah, raoult's law.
i don't know why i couldn't think of that.
thanks for your help

[Merek Roman]

I am doing a design project that required finding the BP, using a non-ideal approach I used the Van Laar model, which you find Psat -> gamma @ azeotrope conditions -> activity coefficients -> new gammas -> then iterate this equation until you get the pressure you want by varying temp Pcalc= gammai*xi**psati (make sure you make gammai,xi all independent of their equations as they are constants)