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Ideal Solution and Raoult's Law


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Well as I'm sure most of you will know I'm more of a Physicist than a Chemist, so, please excuse the rookieness:


Okay I'll cut to the chase; I intend to carry out an experiment regarding Raoult's law and its variations, i would love some pointers, I need to prove the Law and its variations i presume for A-A A-B and B-B solutions (some explanation on wtf those are might be nice too :D) I presume (notice, there are lots of presumptions going on here...) that i need an Ideal solution (or 10 of them...) and maybe a few that nicely show the variations of the Law. I know that the solution should be very dilute, (but i figured, if it was too dilute i might as well just investigate saturated vapor pressure which i don't want to do...)


as you can see I need help on this one... anything you think might help would be most appreciated !!!


BUMP sorry but I'm getting desperate here !


Bump & Update


Okay, since I made this post I have asked arround elsewhere, as I have had 0 response from you guys! But hey, you get what you pay for....right :P

anywhoo, i have decided on a method, which is to mix different volumes togeter i.e. chemical X and Y

100%X 0%y

75%X 25%Y

50%X 20%Y

25%X 75%Y

0%X 100%Y


Then produce a graph. Hopefully ideal(ish) solutions will provbide linear lines for bpt and non ideal's will skew somewhat!

now all i need is my other questions answerd, i.e. what solutions to use...

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Yea JC if I knew what I was on about it would help, but since My retarded question gained little response I will post my findings below, to aid anyone else in the unfortunate position of having to do this Experiment:


Raoult’s law states:


The vapour pressure of an ideal solution is dependent on the vapor pressure of each chemical component and the mole fraction of the component present in the solution.


Vapour pressure of a solvent in an ideal solution = the mole fraction of the solvent x the vapour pressure of the pure solvent.


Vapour pressure varies with the strength of the intermolecular forces in the liquid.


The Chemicalls I'm gunna use are the following (N.B.) ideal means it demonstrates how an ideal solution behaves according to Raoult's law

+ve means it shows positive deviation, and i bet you can work out for yourselves what the -ve stands for...



1) Benzene + toluene (AKA methylbenzene)(ideal)

2) Trichloromethane(CHCl3) + ethoxyethane (-ve)

3) ethanol + water (+ve)


as far as method is concerned, well, its surprisingly easy! make up a number of solutions i.e.


100%A 0%B

75%A 25%B

50%A 50%B

25%A 75%B

0%a 100%B


heat under reflux with anti bumping granules etc etc and record the boiling temp


after that it becomes pretty apparent. just draw up a graph with %soln on X-axis and temp on the Y-axis


Job done !


I hope someone in need finds this in a few years time and appreciates it, i sure know i would have !


Oh and if anyone wants explanation on why these particular chemicals show these trends PM or email me, or carrier pigeon...

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  • 2 weeks later...
This thread (and the OP) apparently is suffering from the condition known as "I think everyone knows what I'm talking about" syndrome...
yea, yea it is, but I've got it figured now, I just have 30 hours of lab time to botch-together an experiment :doh:
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