Acetic acid: chemical formula, properties and application

Ethanic acid is better known as acetic acid. It represents the formula CH3COOH. It belongs to the class of carboxylic acids, whose molecules contain functional monovalent carboxyl groups COOH (either one or several). About it you can provide a lot of information, but now attention should be noted only the most interesting facts.


How it looks can be understood from the image below. The chemical formula of acetic acid is uncomplicated. This is due to many: the compound itself is monobasic, and it belongs to the carboxyl group, which is characterized by easy proton cleavage (stable elementary particle). This compound is a typical representative of carboxylic acids, since it has all their properties.

chemical formula of acetic acid

The bond between oxygen and hydrogen (−COOH) is highly polar. This causes an easy process of dissociation (dissolution, decomposition) of these compounds and the manifestation of their acidic properties.

The result is a proton H+and acetate ion CH3COO−. What are these substances? Acetate-ion is a ligand associated with a specific acceptor (an object receiving something from a donor compound), forming stable acetate complexes with cations of many metals. And a proton is, as mentioned above, a particle capable of capturing an electron from the electron M-, K- or L- shells of an atom.

Qualitative analysis

It is based precisely on the dissociation of acetic acid. Qualitative analysis, also called a reaction, is a combination of physical and chemical methods that are used to detect compounds, radicals (independent molecules and atoms), and elements (a combination of particles) that make up the analyte.

Using this method it is possible to detect salts of acetic acid. Everything looks not as difficult as it may seem. A strong acid is added to the solution. sulfuric, for example. And if the smell of acetic acid appears, then its salt is present in the solution. How it works? The remains of acetic acid, which are formed from salt, are bound at that moment with hydrogen cations from sulfuric acid. What is the result? The appearance of a larger number of molecules of acetic acid. Dissociation happens.


It should be noted that the compound under discussion is capable of interacting with active metals. These include lithium, sodium, potassium, rubidium, francium, magnesium, cesium. The latter, by the way, is the most active. What happens at the time of such reactions? Hydrogen is evolved, and the formation of notorious acetates occurs. Here is the chemical formula of acetic acid that reacts with magnesium: Mg + 2СН3COOH → (CH3COO)2Mg + H2↑.

ethanoic acid

There are ways to get dichloroacetic (CHCl2COOH) and trichloroacetic (CCl3COOH) acids. In them, the hydrogen atoms of the methyl group are replaced by chloric. There are only two ways to get them. One is the hydrolysis of trichlorethylene. And it is less common than the other, based on the ability of acetic acid to be chlorinated by the action of chlorine gas. This method is simpler and more efficient.

Here is how this process looks like the chemical formula of acetic acid that interacts with chlorine: CH3COOH + Cl2→ CH2CLCOOH + HCL. Only it is worth clarifying one thing: this is simply chloroacetic acid, the two aforementioned are formed with the participation of red phosphorus in small quantities.

Other transformations

It is worth noting that acetic acid (CH3COOH) is capable of entering into all the reactions that are characteristic of the notorious carboxylic group. It can be restored to ethanol, monohydric alcohol. For this, it is necessary to act on it with lithium aluminum hydride, an inorganic compound that is a powerful reducing agent often used in organic synthesis. Its formula is Li (AlH4).

glacial acetic acid

Acetic acid can also be converted to the acid chloride, the active acylating agent. This occurs under the influence of thionyl chloride. By the way, it is a sulfuric acid chloride. Its formula is H2SO3. It is also worth noting that the sodium salt of acetic acid decarboxylates when heated with alkali (carbon dioxide molecule is excluded), as a result of which methane (CH₄) is formed. And he, as you know, is the simplest hydrocarbon, which is lighter than air.


Glacial acetic acid - often the compound in question is called that way. The fact is that when it cools down to only 15-16 ° C, it passes into a crystalline state, as if it is frozen. Visually, this is really very similar to ice.If there are several ingredients, you can conduct an experiment, the result of which will be the transformation of acetic acid into ice. It's simple. From the water and ice, you need to prepare a cooling mixture, and then lower into it the previously prepared tube with acetic acid. After a few minutes, it crystallizes. In addition to the compound, it requires a beaker, a tripod, a thermometer, and a test tube.

Harm substance

Acetic acid, whose chemical formula and properties were listed above, is unsafe. Her couples irritate the mucous membranes of the upper respiratory tract. The threshold for the perception of the smell of this compound in the air is in the region of 0.4 mg / l. But there is also the concept of maximum permissible concentration - a sanitary and hygienic standard, approved by law. According to him, in the air can be up to 0.06 mg / m³ of this substance. And if we are talking about working rooms, the limit increases to 5 mg / m3.

acetic acid dissociation

The destructive effect of acid on biological tissues directly depends on how diluted it is with water. The most dangerous solutions with a content of this substance more than 30%.And if a person accidentally comes into contact with a concentrated compound, he will not be able to avoid chemical burns. This categorically cannot be allowed, since after this coagulation necrosis begins to develop - the death of biological tissues. Lethal dose is only 20 ml.


It is logical that the higher the concentration of acetic acid, the more harm it will have in case of contact with the skin or into the body. Common symptoms of poisoning include:

  • Acidosis. Acid-base balance is shifted towards increasing acidity.
  • Blood clotting and violation of its clotting.
  • Hemolysis of erythrocytes, their destruction.
  • Liver damage.
  • Hemoglobinuria. In the urine hemoglobin appears.
  • Acute renal failure.
  • Toxic burn shock.

Degrees of severity

It is customary to single out three:

  1. Easy It is characterized by small burns of the esophagus and mouth. But there is no blood clotting, and the internal organs continue to function normally.
  2. Average. There is intoxication, shock and thickening of the blood. The stomach is affected.
  3. Heavy The upper respiratory tract and the walls of the digestive tract suffer greatly, and renal failure develops. Maximum pain shock. Perhaps the development of burn disease.

 acetic acid 70

Acetic acid vapor poisoning is also possible. It is accompanied by severe runny nose, coughing and tearing.

Giving help

If a person is poisoned with acetic acid, then it is very important to act quickly to minimize the consequences of what happened. Consider what to do:

  • Rinse the mouth. Do not swallow water.
  • Make a probe gastric lavage. It will take 8-10 liters of cold water. Even blood admixture is not a contraindication. Because in the first hours of poisoning large vessels still remain intact. So there will be no dangerous bleeding. Before washing you need to make analgesics analgesics. The probe is lubricated with liquid paraffin.
  • Do not induce vomiting! Neutralize the substance can be burnt magnesia or drug "Almagel".
  • None of the above? Then give the victim ice and sunflower oil - you need to take a few sips.
  • Allowed to use the affected mixture of milk and eggs.

It is important to provide first aid within two hours after the incident. After this period, the mucous membranes swell, and it will be difficult to reduce the pain of a person. And yes, in no case can you use soda.The combination of acid and alkali will give a reaction, during which carbon dioxide and water are produced. And such a formation inside the stomach can be fatal.


Aqueous solutions of ethanoic acid are widely used in the food industry. These are vinegars. To obtain them, the acid is diluted with water to get a 3-15% solution. As an additive, they are labeled E260. Vinegars are a part of various sauces, and they are also used for canning products, pickling meat and fish. In everyday life, they are widely applicable for removing scale, stains from clothes and utensils. Vinegar is an excellent disinfectant. They can handle any surface. Sometimes it is added when washing to soften clothes.

acetic acid concentration

Also, vinegar is applicable in the preparation of fragrant substances, medicines, solvents, in the production of acetone and cellulose acetate, for example. Yes, and acetic acid is directly involved in dyeing and typography.

In addition, it is used as a reaction medium for the oxidation of a variety of organic substances. An example from industry is the oxidation of para-xylene (an aromatic hydrocarbon) by atmospheric oxygen to terephthalic aromatic acid.By the way, since the vapors of this substance have a sharp irritating odor, it can be used as a substitute of ammonia for removing man from fainting.

Synthetic acetic acid

This is a flammable liquid, which belongs to substances of the third class of danger. It is used in industry. When working with it, personal protective equipment is used. Store this substance in special conditions and only in a certain container. Typically, this is:

  • clean rail tankers;
  • containers;
  • tank trucks, barrels, stainless steel tanks (capacity up to 275 dm3);
  • glass bottles;
  • plastic drums with a capacity of up to 50 dm3;
  • sealed stainless steel tanks.

how to make vinegar from acetic acid

If the liquid is stored in a polymer container, then it is at most a month. Also, it is categorically not allowed to store this substance together with such strong oxidizing agents as potassium permanganate, sulfuric and nitric acid.

The composition of vinegar

About him, too, should say a few words. The composition of the traditional, all the usual vinegar includes the following acids:

  • Apple Formula: NOOCHCH (OH) COOH. It is a common food additive (E296) of natural origin.Contained in immature apples, raspberries, mountain ash, barberry and grapes. In tobacco and tobacco is presented in the form of nicotine salts.
  • Dairy. Formula: CH₃CH (OH) COOH. Formed by the breakdown of glucose. Food additive (E270), which is obtained by lactic fermentation.
  • Ascorbic Formula: C₆H₈O₆. Food additive (E300), used as an antioxidant that prevents oxidation of the product.

And of course, ethane compound is also included in vinegar - this is the basis of this product.

How to dilute?

This is a frequently asked question. Everyone has seen the sale of acetic acid 70%. It is bought to prepare mixtures for national treatment, or for use as a seasoning, marinade, additive in sauce or seaming. But you can not use such a powerful concentrate. Therefore, the question arises of how to dilute acetic acid to vinegar. First you need to protect yourself - wear gloves. Then clean water should be prepared. For solutions of different concentrations, you will need a certain amount of liquid. Which one Well, look at the table below and dilute the acetic acid in view of the data.

Vinegar concentration

Initial vinegar concentration 70%


1: 1.5 (ratio - one part vinegar to the nth part of the water)

















In principle, nothing complicated. To get a 9% solution, you need to take the amount of water in milliliters using this formula: 100 grams of vinegar multiplied by the initial rate (70%) and divided by 9. What is the result? The figure is 778. From this, 100 are subtracted, since 100 grams of acid was originally taken. It turns out 668 milliliters of water. This amount is mixed with 100 g of vinegar. The result is a whole bottle of 9 percent solution.

Although, you can act even easier. Many are interested in how to make vinegar from acetic acid. Easily! The main thing is to remember that for one part of a 70 percent solution it is necessary to take 7 parts of water.

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