Ethanol is a volatile, flammable, colorless liquid with a slight chemical odor. It is used as an antiseptic, a solvent, a fuel, and, due to its low freezing point, the active fluid in post-mercury thermometers.Its structural formula, CH 3CH 2OH, is often abbreviated as C 2H 5OH, C 2H 6O or EtOH.thanol is the systematic name defined by the International Union of Pure and Applied Chemistry (IUPAC) for a molecule with two carbon atoms (prefix eth-), having a single bond between them (suffix -ane), and an attached functional group-OH group (suffix -ol).