Ethanol Molecular Formula and Empirical Formula

Ethanol is the type of alcohol found in alcoholic beverages and commonly used for labwork and chemical manufacture. It is also known as EtOH, ethyl alcohol, grain alcohol, and pure alcohol.

Molecular Formula 

The molecular formula for ethanol is CH₃CH₂OH or C₂H₅OH. The shorthand formula is simply EtOH, which describes the ethane backbone with a hydroxyl group. The molecular formula describes the type and number of atoms of elements present in an ethanol molecule.

Empirical Formula

The empirical formula for ethanol is C₂H₆O. The empirical formula shows the ratio of elements present in ethanol but does not indicate how the atoms are bound to each other.

Chemical Formula

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Absolute Alcohol Definition and Formula

By Anne Marie Helmenstine, Ph.D.

There are multiple ways to refer to the chemical formula of ethanol. It is a 2-carbon alcohol. When the molecular formula is written as CH₃-CH₂-OH, it is easy to see how the molecule is constructed. The methyl group (CH₃-) carbon attaches to the methylene group (-CH₂-) carbon, which binds to the oxygen of the hydroxyl group (-OH). The methyl and methylene group form an ethyl group, commonly denoted as Et in organic chemistry shorthand. This is why the structure can of ethanol be written as EtOH.

Ethanol Facts

Ethanol is a colorless, flammable, volatile liquid at ordinary temperature and pressure. It has a strong chemical odor.

Other Names (not already mentioned): Absolute alcohol, alcohol, cologne spirit, drinking alcohol, ethane monoxide, ethylic alcohol, ethyl hydrate, ethyl hydroxide, ethylol, ghydroxyethane, methylcarbinol

Molar mass: 46.07 g/mol
Density: 0.789 g/cm³
Melting point: −114 °C (−173 °F; 159 K)
Boiling point: 78.37 °C (173.07 °F; 351.52 K)
Acidity (pKa): 15.9 (H₂O), 29.8 (DMSO)
Viscosity: 1.082 mPa×s (at 25°C)

Use in Humans

Routes of administration
Common: oral
Uncommon: suppository, ocular, inhalation, insufflation, injection
Metabolism: Hepatic enzyme alcohol dehydrogenase
Metabolites:  acetaldehyde, acetic acid, acetyl-CoA, water, carbon dioxide
Excretion: urine, breath, perspiration, tears, milk, saliva, bile
Elimination half-life: constant rate elimination
Addiction risk: moderate

Uses of Ethanol

• Ethanol is one of the oldest known recreational drugs used by man. It is a psychoactive, neurotoxic drug capable of causing intoxication.
• Ethanol is used as a fuel. It is used for motor vehicles, plus also as a fuel for home heating, rockets, and fuel cells.
• The alcohol is an important antiseptic. It is found in hand sanitizer, antiseptic wipes, and sprays.
• Ethanol is a solvent. It is particularly useful because it is intermediate between polar and nonpolar solvents, so it can be used to help dissolve a wide variety of solutes. It is found as a solvent in many everyday products, including perfumes, paints, and markers.
• It is used as a fluid in thermometers.
• Ethanol is an antidote to methanol poisoning.
• The alcohol is used as an antitussive agent.
• Ethyl alcohol is an important chemical feedstock. It serves as a precursor for ethyl esters, acetic acid, ethyl halides, ethyl amines, and diethyl ether.

Grades of Ethanol

Because pure ethanol is taxed as a psychoactive recreational drug, different grades of alcohol are in use:

• pure ethanol
• denatured alcohol - ethanol made unfit to drink, usually by adding a bittering agent
• absolute alcohol - ethanol that has a low water content -- not intended for human consumption (200 proof)
• rectified spirits - azeotropic composition of 96% ethanol and 4% water