Today’s Imponderable: Why Can’t Oil and Water Mix?
December 8, 2015 | klein
You’ve likely heard the expression “like oil and water,” and you may have even witnessed this strange phenomenon firsthand if you’re an avid baker. Although it is fairly common knowledge, do you really know why oil and water can’t mix?
The main reason why these two liquids can’t mix is because they’re too into themselves—literally. Water molecules are very attached to one another and though they usually mix with other liquids, they’ve met their match with oil, which is also very attached to its own molecules. In more scientific terms, water molecules are polar in nature and can only dissolve other polar molecules. Because oil is non-polar, it cannot dissolve in water. This causes the two liquids to almost seamlessly separate, and the oil then floats on top because it has a lower density than the water.
In nature, you can observe this phenomenon on water birds or animals like beavers. Their oily coats and feathers repel water, which keeps them warm and dry in the winter!