# Question about Methanol's hygroscopic properties



## TheBossQ (Aug 15, 2009)

Does anyone know how much water Methanol will absorb before it becomes saturated? Is it a 1:1 by weight or volume?
I read that a 50/50 mix of water and methanol results in an approximate 5% reduction of total volume.
i.e. 50ml water + 50ml methanol = 95ml combined solution.
I've searched the net a bit and didn't come up with anything.


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## [email protected] (Oct 6, 2009)

*FV-QR*

You can have any ratio you please... You should be mixing by volume. If you go by weight meth is less dense than water so it will work out differently...below you can see what i mean.
Meth= .825oz per fluid oz
Water= 1.04375oz per fluid oz
Weight Proportion:
x ............ y
--------- = ----------
118.06875 100


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## TheBossQ (Aug 15, 2009)

*Re: FV-QR ([email protected])*

Hi Quintin,
Thanks for the reply.
My question is more about saturation than mixing ratios. Being that Methanol is hygroscopic, it will absorb water vapor freely.
If I left a given volume (let's say 50ml) open to atmosphere, in an environment in which the Methanol would not evaporate, how much water (by volume) would the Methanol absorb before it became saturated?
Though, after many searches on the internet, I realize I am asking the wrong question. Really, I am looking for the solubility of Methanol in water. Methanol is miscible with water, therefore will dissolve in water at any ratio to form a homogeneous solution. Both water and methanol are polar, which is what causes their attraction. But at some point, due to saturation, methanol will no longer attract water. I am trying to find that volumetric ratio at which Methanol becomes saturated by water.
Thanks again.


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## [email protected] (Oct 6, 2009)

*FV-QR*

Gaaah...you're killing me! Having to think back to Chem II is not fun....All i can tell you is once you get over like 60% Meth the mixture becomes flamable (IIRC) so below that i'd say it's "saturated"


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