Water has a density of about 0.9980 g/cm^3 at 20 degrees C. Ethyl alcohol only has a density of 0.785. In a booze like vodka, which is basically ethyl alcohol and water, why doesn’t all the alcohol float to the top?
Just curious…
Ethyl alcohol has a very high chemical affinity for water and mixes and bonds with it nicely. It does not want to push the water out of solution.
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Why doesn’t salt settle out of salt water? When one compound dissolves in another, the molecules, atoms, or ions are attracted to one another. So the OH in the alcohol has water molecules hydrogen bonded to it hold ing it is the water.
the alcohol and water molecules all mixed up like being that way, even better than the alcohol being by itself. it is a lower energy state.
The unspoken part of the question is, “Oil and water have different densities and separate, so why don’t alcohol and water?” The reasons why water and alcohol stay mixed are given above, but the reason for oil and water to separate doesn’t have anything to do with the differences in their density. The difference in density explains only why the oil ends up on top.
Thanks, fellers! I understand the dissolving process (i.e., salt in water). Didn’t realize the same was happening with the ethanol and water. Ignorance fought!
And giving a bit more of an explanation on why water and ethanol “like” each other, it’s because both have the ability to form hydrogen bonds. Bigger alcohols aren’t as good at this (the organic part gets in the way), but methanol is even better - it also has the nasty defect of being poisonous to humans, tho.
Put in terms of the fundamental forces, the electromagnetic force comprising their intermolecular interactions is stronger than the gravitational force acting on the individual molecules.
Is Hygroscopy the reason why alcohol dehydrates a person so much?
No, that’s because the chemical reactions involved in degrading the alcohol use up water, and because often when people are drinking alcohol they’re not drinking as much water as they need. If your body is at a stage where it needs “two glasses of water” and you give it “two glasses of 25% alcohol”, you’re missing half a glass of water.
But, I bet they actually do separate out a bit, just not much. Isn’t that the same principle by which uranium hexafluoride gasses separate out according to the atomic weight of the uranium atom, in centrifugal enrichment processes?
This is in large part due, I remember learning, to alcohol suppressing the action of ADH, a hormone that increases water reabsorption by the kidney. When ADH action is down, water reabsorption is down, and I.P. Freely starts renting beer instead of buying it.