What is acetic acid?
It is called acetic acid , methyl carboxy acid or also ethanoic acid to an organic compound can be as acetate ion or ethanoate and also present in the vinegar, the liquid which confers characteristic aromas and sour taste.
It is a weak acid, usual result in certain fermentation processes, such as those that take place in wine (it is made, it is said to be “vinegar”) or in fruits.
The acetic acid is widely used in organic chemistry and in various industrial processes, so there are different ways of obtaining: methanol carbonylation, oxidation of ethylene or oxidative fermentation, and bacteria do Mycoderma aceti and requires the presence of oxygen.
Its massive production in the whole world is due to the fact that it is a useful compound in obtaining other organic substances, such as acrylic acid.
Characteristics of acetic acid
Acetic acid has the chemical formula C 2 H 4 O 2 and the semi-developed formula CH 3 COOH. From there it follows that it is a molecule of methyl (CH 3 ) adhered by a single bond of a carbon atom to a carboxyl group (-COOH).
Since acetic acid has a polar group (-COOH) and an apolar group (-CH 3 ) in its molecular composition, it is an ambiguous substance with respect to its solvents.
For example, it is soluble in water, but also in most organic substances, such as certain ethers.
The acetic acid has a molecular weight of 60.05 g / mol of substance and a molar mass of 60.02 g / mol.
The density of acetic acid is 1049 kg / m 3 (g / cm 3 ). Its melting point is 16.6 ° C and its boiling point is 117.9 ° C.
It can be a clear liquid with strong vinegar smell and acid taste, or a colorless solid in the form of small regular crystals.
Vinegar and acetic acid
The vinegar contains 5 to 3% of acetic acid dissolved in water, together with small amounts of tartaric acid and citric acid.
It was discovered for the first time in the work of wine because the poorly guarded barrels in which air and oxygen seeped, underwent the fermentation process of the Mycoderma aceti bacteria , which converts ethyl alcohol into vinegar. It was said then that the wine was “itchy”.
Vinegar, however, is an important part of human gastronomy and is produced from different sources: apples, grapes or artificial alcohols.
It is indispensable in the preparation of pickles, ceviche, pickles, or as dressing for salads. It is also used in food preservation because it slows the decomposition processes of organic matter.
As we have said, it is a very weak acid, in spite of being flammable and corrosive at the same time, as well as a hygroscopic substance (which seeks to react with water).
In high concentrations can therefore irritate the skin, eyes or mucous membranes, both by inhalation and swallowing. It is an acid often secreted by living beings, as metabolite and substrate of acetyl transferases enzymes.
Glacial acetic acid
Glacial acetic acid is the result of acetic acid freezing, in which the water forming part of the compound forms easily removable crystals of the compound, since the rest does not change phase.
Thus, when we speak of glacial acetic acid, we refer to anhydrous acetic acid, that is, without water.
In general, the acetic acid with which there is contact in vinegar and other solutions is found in such low concentrations that it is not risky at all.
However, in high concentrations, it is an irritant capable of causing skin burns, permanent damage to the eyes, and irritation of the mucous membranes.
It is not a particularly flammable compound, but in solutions of more than 25% its gases can be equally corrosive and dangerous for human and animal life, so it is handled in a smoke extraction hood.
Acetic acid has many applications in different human industries, such as:
- It is used as an additive in the control of wax moths ( Galleria mellonella
) in beekeeping.
- It is an important component (forming salts or esters) to make nylon, rayon, cellophane and other synthetic films.
- It is used in fixing substances for the preservation of organic tissues in laboratories (such as formaldehyde).
- It is used in chemicals for photographic development.
- It is used as a dye to reveal the lesions of the Human Papillomavirus (HPV) in medicine.
- It is a usual component of commercial cleaners and spot removers.
- It has many culinary uses such as vinegar: to wash vegetables and greens, as a dressing, etc.