EmmisonJ
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general solubility / density question (water and oils)
if you have 2 liquids of equal volueme and different densities, both are insoluble in water, one is of a lighter density than water and one is of a
heavier density of water. mix them together to form a solution, then put it with an equal amount of water. do the 2 water insoluble liquids come
together to form a new density somewhere in the middle.... or at least "act" like they have? i suppose them actually coming together would be a more
azeotropic behavior and may not be the correct way to look at this.
in case i'm not making much sense, this question is the result of seeing 2 things happen:
1. i've read instances where if you need to extract a nonpolar compound from a solution with a lot of water in it then depending upon the amount of
solvent used to extract, sometimes the solvent / nonpolar layer floats and sometimes it sinks. so there seems to be a factor (most likely the volume
of these liquids) where it seems that a small amount of solvent, the nonpolar layer will float, but with a large amount of solvent then the nonpolar
layer will sink.
2. here's an example i've seen happen that must be related and would love to understand what's causing this. i had a solution of oils, there were
about 4 different oils of all different densities that were in an equal amount of water (1:1 water il solution). there was some yellowish oil that sank to the bottom and some clear oil that floated, in the middle was
a water layer. what was really strange was that i saw a "glob" of yellow (heavier density) oil on the top, it looked like a large bubble. this large
"glob" of oil was being held on the top oil layer by clear (lighter density) oil. the clear oil layer had a layer of its own on top of the water and
literally i could see the clear oil layer completely wrapped around the yellow oil "glob", holding it above the water layer and not allowing it to
sink. i shook the glass a little bit and the "glob" did not break free, it just wabbled around like a jellyfish with the clear oil still having a
strong grip on it. is this due to surface tension?
thanks 
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PHILOU Zrealone
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1°)Like likes like so hydrophobic tends to join together!
2°)If the two solvents are 100% miscible they will be homogenous whatever the % of each in the mix; the density will vary as a function of the %
composition of the two...and so it will sink into (or float on) water. You will only get two phases.
3°)If the two solvents are partially miscible then you get multiphasic differentiation, each phase displaying a different composition will thus
display a different density and so with water you might get 3 phases and by shaking the two oily phases gather and slowly decantate into the water, at
first the two oily phase stiks to each other then big "bubblelike" structure sinks from the top phase or lift from the bottom phase...achieving a
triphasic system...the last bubbles/globs often don't have enough "energy" (density/weight gradient) to withdraw the interfacial lipophilic attraction
(tensile strenght) and remain suspended on the edge from lifting or from sinking...
[Edited on 8-4-2009 by PHILOU Zrealone]
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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EmmisonJ
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thanks! reading up on multiphasic liquids was very interesting, i would've never came across that phrase if it weren't for your reply
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