Stearic acid is the common name for octadecanoic acid, which is a saturated fatty acid with the chemical formula of C18H36O2. A fatty acid is an organic compound made up of a long, unbranched carbon backbone that ends with a carboxyl group, or –COOH. A carboxyl group is made up of one carbon atom bonded to an oxygen atom by a double bond, and a hydroxide group made up of an oxygen and hydrogen atom bonded together.
The oxygen and hydrogen atoms are bonded to the end carbon atom in such a way that they give it a charge, allowing it to form hydrogen bonds with other molecules. A hydrogen bond is a chemical bond that forms between a hydrogen atom of one molecule and a negatively-charged atom in another molecule. Examples of atoms that carry negative charges are oxygen and nitrogen. Stearic acid molecules bond when hydrogen bonds form between the double-bonded oxygen of one molecule and the hydrogen of the hydroxide group of the other molecule.
To understand the structure of this substance, it is important for individuals to remember that a carbon atom can bond to four other atoms or molecules. A carbon atom that has four atoms or molecules bonded to it is in its most stable form, making it relatively unreactive. As this acid is an organic compound, or occurs in living things, it is very important that it is stable and does not break down easily. It is a saturated fatty acid, which means the carbon backbone is made up of a long chain of carbon atoms bonded together by single bonds and with two hydrogen atoms bonded to each of the internal carbon atoms.
Stearic acid is used for many different household products. It is used as a lubricant, a hardener, and an emulsifier, a chemical that allows oils and water to mix. Many common items contain this acid, including soaps, cosmetics and lotions, stick deodorants, and candles. In candles, it makes the wax more opaque and less likely to drip. It also hardens them and increases the melting point, so the candle will last much longer.
Purified stearic acid is a waxy substance that is odorless and often takes the form of white or yellow waxy flakes. When it is heated, it becomes a clear liquid. It is one of the most commonly occurring fatty acids and is found in a number of animal fats and vegetable oils, including beef fat and cocoa butter. The acid is often used in the production of margarine, shortening, spreads, and baking products.