Why can't oil dissolve in water?

Have you ever washed your hands full of oil and realized that it could not be washed with water? Or once you heard about oil spills, you wonder why the whole ocean water cannot dissolve that small amount of oil? There are two main reasons why oil cannot be dissolved in water and these two causes are related to very small components called molecules.

Everything around us is made up of very small particles called molecules. The way two substances come into contact depends on the physicochemical interaction between the molecules of the substance.

Oil and water have different molecular densities

The first reason why oil and water cannot mix together is because the molecules of each bond are in different ways. Water molecules are more closely linked. Imagine inside a glass of water that contains more molecules than there are stars in the sky. This means that if you compare the same amount of water and oil, the number of molecules in the water will be higher than the oil. That explains why water always sinks and oil always floats up above.

Polarization

There is another reason why water and oil cannot dissolve into one another due to polarization. More precisely, the electronegativity of each element is different , in the molecule, this difference in electronegativity will determine whether the molecule has a polarizing bond (from 0.4 to 1.8). Water is a polar molecule. It is made up of 2 hydrogen atoms and 1 oxygen atom. These three atoms are joined together in a straight-line form, which forms a V-shape. The electrons in the molecule are more at the position of the oxygen than the hydrogen, so the position of the oxygen will be negative and negative. Again, two hydrogen heads have an anode.

Polarized molecules are only soluble in polar solvents. Non-polar molecules are only soluble in non-polar solvents. Sadly, oil has a non-polar molecular structure. And so, when oil is added to water, it only floats to the surface due to cause 1 and not dissolving into water.

Of course, with today's advanced technologies, we already have detergents or soaps that help wash our hands or household tools that clean oil spills.

Reference: Education, Smithsonianmag, Wired.