Does Salad Oil Dissolve in Ethanol?

One of the most difficult issues in cooking is knowing what things will dissolve and mix well. In chemistry, this is called the issue of miscibility. A lot of what determines the miscibility of two substances has to do with their basic chemistry. To understand why salad oil can dissolve in ethanol, it is important to understand the principles behind this for future reference and a more complete understanding.

Identification

The study of substances mixing is known as miscibility. It also can apply to gases and solids, though in general these are not thought to "mix" in the same way. The principles of miscibility help explain why certain things in the kitchen, such as oil and water, do not mix, but others, such as oil and ethanol, do.

Features

Miscibility has to do with polar and nonpolar groups. A polar group is a part of a compound that is slightly electrically charged, either positively or negatively. Nonpolar compounds have no electrical charge. What gives polar compounds their charge is that there are certain regions within a polar molecule that have a greater electrical attraction to electrons (which are negative) than other regions. Water is an example of a polar molecule. Salad oil is nonpolar. Ethanol has aspects of both.

Function

Have you heard of the saying "like dissolves like"? It refers to the principle that polar compounds will dissolve with other polar things, and nonpolar compounds prefer to be in the presence of other nonpolar molecules. This is because polar molecules are electrically drawn to other polar molecules. Nonpolar molecules, then, are repelled by them, and in an effort to avoid making contact with polar molecules, will form little globules. This is why when oil is poured into water, it forms little drops that don't mix.

Considerations

So why do salad oil and ethanol mix? Salad oil is very nonpolar, and ethanol has both polar and nonpolar parts. The salad oil is attracted to the nonpolar parts of the ethanol, which allows the two to mix. Thus if you're trying to cook something that requires salad oil, you may be better off trying to get it to mix in with some ethanol (in the form of vodka, perhaps) than trying to mix your ingredients together in water.

Expert Insight

What is particularly interesting is that ethanol is also miscible in water. This is because it also has polar components, which is why something high in alcohol, for example vodka or whiskey, can be dissolved in water. Ethanol is called amphipathic for this reason, meaning it has both polar and nonpolar ends. The other interesting consequence is that ethanol can then be dissolved in water to make it less polar. As a result, a mixture of ethanol and water can dissolve a certain amount of salad oil. The amount of salad oil that can dissolve in this mixture will depend on the amount of ethanol.