Is acetic acid weak

acetic acidAcidsAcetic acid is a simple and weak carboxylic acid that occurs in all living things and, for example, arises from alcohol during bacterial acetic acid fermentation. It is contained in vinegar in a deep concentration. Virtually pure and anhydrous acetic acid is known as glacial acetic acid. Acetic acid is used, among other things, as a disinfectant, cleaning agent, caustic agent, reagent and for the production of active ingredient salts. In high concentrations it is corrosive and as a pure substance it is flammable.

synonym: Acidum aceticum, Acidum aceticum glacialePhEur, E 260, ethanoic acid, methanecarboxylic acid, Acetic acid, E 260, Ethanoic acid, AcOH


Acetic acid is available as an aqueous solution in various concentrations in pharmacies and drug stores.

Structure and properties

The acetic acid (C.2H4O2, Mr = 60.1 g / mol) or CH3-COOH is the simplest carboxylic acid after formic acid. It consists of a methyl and a carboxyl group. As a pure substance, it is available as a clear, volatile, colorless liquid and, due to its melting point of around 17 ° C, also as a crystalline mass and is miscible with water. Acetic acid has a pungent odor and is caustic.

In the pharmacopoeias, a distinction is made between the following concentrations (examples):

Their salts and esters are called acetates, for example the auxiliary sodium acetate. Some active pharmaceutical ingredients are also available in this form. The Latin name is derived from Acetum (Latin vinegar).

Acetic acid is a natural substance that is produced, for example, after alcoholic fermentation from ethanol (alcohol) through bacterial oxidation. One speaks of acetic acid fermentation or fermentation, which occurs in the acetic acid bacteria (e.g. Acetobacter) takes place. It is typically found in vinegar in a concentration of at least 4.5% to 5%, with the acidity of the products differing.

Ethanol + oxygen (O2) → acetic acid + water (H2O)

Acetic acid occurs as a metabolic product in all living things. With a pKa of 4.76 it is only a weak acid.

Acetic acid fermentation, click to enlarge. Illustration © PharmaWiki


Acetic acid (ATC G01AD02, ATC S02AA10) has acidic, corrosive, irritating, preservative and antimicrobial properties.

application areas

There are numerous areas of application for acetic acid in suitable dilutions (selection):

unwanted effects

The hazard potential of acetic acid depends on its concentration. Glacial acetic acid (99%) is corrosive and can cause burns to the skin, mucous membranes and eyes. In addition, it must be ensured that both the liquid and its vapors are flammable (!) Appropriate precautionary measures must be observed. You can find them in the safety data sheet. Solutions with a lower concentration are not flammable, but they are still irritating or corrosive.

see also

Vinegar, ethyl acetate, formic acid, acids, acetic anhydride, sodium acetate, carboxylic acids

  • Pharmaceutical product information (CH)
  • European Pharmacopoeia PhEur
  • Food technology textbooks
  • Pharmacy textbooks
  • Pharmacopoea Helvetica
  • Safety data sheet

Conflicts of Interest: None / Independent. The author has no relationships with the manufacturers and is not involved in the sale of the products mentioned.

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This article was last changed on 11/10/2020.
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