When a nonpolar substance like oil is introduced, it cannot form these favorable interactions with water molecules. In the case of oil and water, the energy gained from water-water hydrogen bonds is much greater than the energy gained from water-oil interactions.
Thermodynamics of Oil and Water: Understanding Stable Immiscible States
By separating into two phases, the water molecules can break free from this restrictive cage, increasing their entropy. When oil is dropped into water, the water molecules do not simply sit idly by.
The water molecules essentially "stick" to each other more tightly than they "stick" to the oil molecules. These bonds form between the positively charged hydrogen atom of one water molecule and the negatively charged oxygen atom of another.
Thermodynamics of Stable Oil and Water Phases
To understand this phenomenon, one must look beyond the surface and examine the invisible world of polarity, charge distribution, and the relentless pursuit of thermodynamic stability that governs every interaction between molecules. This network of hydrogen bonds is incredibly stable and requires energy to break.
More About Why oil don't mix with water
Looking at Why oil don't mix with water from another angle can help expand the discussion and give readers a second clear paragraph under the same section.
More perspective on Why oil don't mix with water can make the topic easier to follow by connecting earlier points with a few simple takeaways.
