acetic acid



We explain what acetic acid is and the formula of this substance. In addition, its physical and chemical properties and its different uses.

Acetic acid is responsible for the sour taste and smell of vinegar.

What is acetic acid?

Acetic acid, also called methylcarboxylic acid or ethanoic acid, is a substance Organic present in the composition of vinegar, responsible for its typical sour smell and taste.

It is a weak acid, common in various processes from fermentation like those that take place in wine (when it becomes vinegary) or in certain fruits. It is commonly used in the kitchen, as a vegetable cleaner or salad dressing (as vinegar, that is, diluted with 3 to 5% solute with water). In proportions pure can be risky for the Health.

Acetic acid formula

Acetic acid responds to the chemical formula C2H4O2.

Acetic acid responds to chemical formula C2H4O2, and its semi-developed formula is CH3COOH.

Seen this way, it is nothing more than a methyl group (CH3-) with a carboxyl group (-COOH) linked by a single bond between their atoms carbon.

Acetic acid physical properties

The appearance of acetic acid is crystalline, at least when it is found as its ion acetate (a salt or ester of the acid). Has a melting point of 16.6 ºC and a Boiling point 117.9 ºC, thanks to which it is possible to separate it from the Water through distillation. It also has a density of 1049 kg / m³ and a moderate acidity of 4.8 pKa.

It is a flammable and corrosive material at the same time, which makes its handling delicate, as it is capable of seriously irritating the skin, eyes, and the digestive tract (by ingestion) or respiratory (by inhalation).

Chemical properties of acetic acid

Acetic acid belongs to the carboxylic acids.

Acetic acid belongs to the carboxylic acids (characterized by the presence of a carboxyl functional chemical group: -COOH), and it is usually located in the classifications between formic or methanoic acid (which has a single carbon atom) and acid propanoic (which already has a chain of three carbon atoms).

It is a weak acid, common as a biological metabolite and as a substrate for enzymes acetyltransferases. It is usually obtained through four methods different:

  • Carbonylation of methanol. Reaction of methanol with carbon monoxide, using iodomethane and a catalyst.
  • Acetaldehyde oxidation. Oxidation of acetaldehyde by oxygen using catalysts.
  • Oxidative fermentation. Fermentation produced by bacteria of the genus acetobacter (bacteria that can convert ethanol to acetic acid in an environment with air).
  • Anaerobic fermentation. Some anaerobic bacteria (which do not use O2 to carry out their metabolism) produce acetic acid from sugars.

Applications and uses

Acetic acid is used in photographic development.

Acetic acid has numerous applications in industry:

  • Control of wax moths (galleriosis) in beekeeping.
  • Important component (in salts or esters) for the manufacture of nylon, rayon, cellophane and other films.
  • Component of fixing substances in the preservation of organic tissues in the laboratory.
  • Part of the chemicals used in photographic development.
  • Medical dye to reveal Human Papillomavirus (HPV) lesions.
  • Component of general purpose cleaners and stain removers.
  • Culinary uses (vinegar).
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