Why don oil and water mix?
Water is what is known as a “polar” molecule. This means that there is unequal sharing of electrons between the hydrogen and the electronegative oxygen. This results in a slight positive charge on the hydrogens and a slight negative on the oxygen in the bent-shaped molecule. This makes water a “polar” solvent. Therefore, only hydrophilic (water-loving) substances are appreciably miscible in water. Oils, on the other hand, are made of hydrocarbon chains. These are chains of carbon atoms bonded to hydrogens. The elements and structure of oils make them non-polar, or “hydrophobic” (water fearing). “Like dissolves like” is a adage to describe the predictable action of a particular solvent on a solute. Only polar substances dissolve in polar solvents; likewise non-polar solutes only dissolve in non-polar solvents. This is why they don’t mix. EDIT: Relative density doesn’t have anything to do with the miscibility properties of oil in water, only explains why it will layer atop of water when
