Oil and water just don’t mix - we all know this to be true. The idea has turned into a popular phrase we use to express when two things don’t go together. But why, exactly, are oil and water destined to be enemies? What’s the science? Here’s a look at oil, water, and chemical bonds:
1. Let’s talk chemistry.
Properties of oil and water all come down to chemistry. Water molecules are what is known as polar, which means that the charge on one end is positive, while the other is negative. Oil, on the other hand, is a nonpolar molecule, so it doesn’t have any sort of charge on its ends.
2. We just don’t bond like we used to.
In chemistry, like attracts like. Water molecules will like other polar molecules and be able to bond with them easily. This is why salt dissolves in water - it’s also a polar molecule and can mix together with the water and stick to the molecules. Oil and water don’t mix well because one is polar and the other is nonpolar. Oil isn’t able to break apart the strong bonds that the water molecules have to one another, so it stays separate. Since the water molecules are more tightly bound, they sink to the bottom, and the oil floats on top as a separate layer.
3. They can be forced to get along.
Oil and water may not mix on their own, but there is a workaround. Emulsifiers have one polar end and one nonpolar end. The polar end will attract the water, and the nonpolar one will attract the oil. In this way, you can get them to mix together. In fact, this is exactly how soap works and why it’s able to get oil off your hands when simple water won’t do!