Quote:
Originally Posted by FoldnDark
FMP.
Right now I'm only about 25% on this explanation. About 50% on something else, and about 25% that you didn't control for everything (temperature for example, or not using DI water) in your experiment. I'd like to reproduce it myself to be sure, and I'd like to get the density of scotch and compare it to the densities of both pure solvents.
Slept on this and now I'm becoming more comfortable with your hypothesis and my explanation. Probably something like 60% vs 30% some other explanation vs 10% that controlling for everything actually will significantly alter the results.
It's often helpful to think of atoms as little magnets, or buckyballs. Then for a liquid just imagine maybe they're greased up well so they can flow and stay constantly in motion relative to each other. So for water, we imagine lots of small buckyballs tightly held due to relatively strong hydrogen bonding creating small spaces between molecules, but still lots of places for sugar because there are so many oxygen's present. For ethanol imagine larger balls (maybe three times larger) less tightly held together because of much weaker hydrogen bonding (this, incidentally accounts for the higher vapor pressure and higher rate of evaporation because the molecules are less tightly bound, meaning it's easier for them to escape liquid phase).
Now if we were to pour one cup of the smaller, tightly bound buckyballs (H2O) into one cup of the larger less tightly bound balls (ETOH), I can see the ETOH being drawn in more tightly by the stronger H2O, while at the same time the bigger ETOH forcing the H2O apart farther, diluting the overall strength of the hydrogen bonds. Now keeping in mind these "balls" are not really spherical, but actually more of a triangle for
H2O, and
ETOH resembles something like a chair or horse, due to the change in symmetry present within the new solution and the stronger H2O molecules thinned out it's not difficult to imagine
bigger yet fewer spaces created for a molecule like sucrose to reside. That would account for a lower solubility and at the same time the lower volume in you expirement. Me thinks.