 Det sker på att de här simpla experimente allow oss att öppna den hydrophobiska effekten på molekylskåpet. Jag ska göra det med en illustrering av kåkning. Om du är bollande på lite pasta kan du möjligen lägga lite olja till vatten. Och de små oljedropplätten kommer att ha att interakta med vatten. Jag kommer att lägga in en annan dropp av olja som jag är generellt idag. Det som kommer att hända runt de här droppar av olja är att vatten kan inte bli hög och bond. Vatten som brukar hända de här droppar med andra vatten kommer att ha att reorientera, för de kan inte hända de här droppar mot olja. Så i stället kommer de att ha att orientera i en complicated fashion. Jag drar det här väldigt snäckligt och schematiskt. Så att de här droppar kommer att ha att formera en nätverkstruktur för att fortsätta de här droppar, åtminstone i första approximationen. Det nätverkstning av det är att de här droppar kommer att vara konstant. Men det är inte en fri lunch, även om det är pasta. Det som händer är att vi är kring de här droppar i terms av entrepi. Vi har nu format en väldigt bra ordentlig läge runt de här droppar. Och de här droppar är sometimes called clatterates. Det är även possible to observe them experimentally, although it's not entirely easy, because it's not a crystal. They are still mobile and everything, but they form a very regular structure to maintain those additive bonds. Now imagine if I took those two drops of oil and at some point in time they would merge to form a slightly larger drop of oil. This droplet does not have to be enormously larger because the volume of oil we can solve inside a droplet corresponds to the radius cubed, right? But on the other hand, so sorry, so merging two droplets would corresponds to a radius that is two to the power of one third larger. But the increase in the area is just going to be the square root of two larger because the area is proportional to the square of the radius. So there will still be a clatterate structure network around this drop of oil. But this one will involve fewer waters. And then there are now going to be a handful of waters that are happy that can form hydrogen bonds out in bulk water. That is the pure solvent. Now if there is an exchange between these, which there will be, what's going to happen is that this process is going to be very advantageous because I will gain entropy going in this way. There won't be any change in energy. While if I go in that direction I'm going to be paying in terms of entropy. So this will lead to the effect that it's much more advantageous to separate phases. In this case that's why you get large drops of oil that might be a centimeter larger water rather than dispersing them all around in the water. And that is exactly the hydrophobic effect. There are two cool things here. The first thing is that although the hydrogen bond is electrostatic in nature, there's no question about that. The hydrophobic effect ends up being entropic in nature because the hydrogen bonds are so strong that we never break them. We just reorient them and that's why it shows up in the entropy. What would you do if you try to solve something in water and it just precipitates? You might try to raise the temperature, right? That would make a lot of sense if you're trying to solve it, say a sodium chloride. The solubility will go up with temperature. But what would happen here? Think a little bit about it. Hit pause. I hope you use our old friend the equation X equals E minus TS or G equals H. But the temperature goes there, right? So if you increase the temperature what's going to happen is that you will make this term more dominant and that's where the entropy went. So what we are predicting here is that if the hydrophobic effect is entropic in nature if you increase the temperature not only will the solubility not go up it's actually going to go down. And that's actually the case. Because that oil you threw in the water when boiling pasta it does not dissolve when you hit 100 degrees centigrade, right? If anything the effect is likely worse although you probably haven't been able to observe that. But the hydrophobic effect becomes worse when the temperature goes up. Not better. So it's quite different from normal solubility of salts.