Question: This is my dad he wants to know: why doesn’t oil mix with water???

Caragh Whitehead answered on 18 Nov 2019:

All substances are either polar or non-polar depending on the charge of the atoms it is made up of. Water is a polar substance and other substances, such as salt, which are also polar can dissolve in water. However, oil is non-polar. This means that it is not attracted to water. Therefore oil is known as hydrophobic (water fearing) and will repel water instead. Because, oil is less dense than water it will always float on top.