If oil floats on water, why is it that when we wash our hands the oil doesn’t get displaced by the water but sticks to our hands instead?

Question

If oil floats on water, why is it that when we wash our hands the oil doesn’t get displaced by the water but sticks to our hands instead?

In: 20

Answer 1

Water molecules are polar, meaning that there are slightly positivly charged parts and slightly negatively charged parts in a water molecule and those attract each other. In oils on the other hand all charge is distributed pretty evenly through the molecule. That means there is no bonding whatsoever happing between oil and water and therefore the water doesn’t take the oil with it when you wash your hands without soap.

Soap molecules have polar and non polar parts so they can act as a sort of bridge and bind oil and water together.

The reason why oil floats on water is because the bonds between water molecules are strong enough to push out any oil molecules between them