Hydrochloric acid - (hydrochloric acid, an aqueous solution of hydrogen chloride), known as the formula HCl, is a caustic chemical compound. Since ancient times, people have used this colorless liquid for various purposes, emitting a light smoke in the open air.
Properties of a chemical compound
HCl is used in various fields of human activity. It dissolves metals and their oxides, is absorbed in benzene, ether and water, does not destroy fluoroplastic, glass, ceramics and graphite. Its safe use is possible when stored and operated under the correct conditions, with all safety precautions observed.
Chemically pure (chemically pure) hydrochloric acid is formed during gaseous synthesis from chlorine and hydrogen, giving hydrogen chloride. It is absorbed in water, obtaining a solution with an HCl content of 38-39% at +18 C. An aqueous solution of hydrogen chloride is used in various fields of human activity. The price of chemically pure hydrochloric acid is variable, and depends on many components.
Scope of application of an aqueous solution of hydrogen chloride
The use of hydrochloric acid has become widespread due to its chemical and physical properties:
- in metallurgy, in the production of manganese, iron and zinc, in technological processes, in metal refining;
- in galvanoplasty - during etching and pickling;
- in the production of soda water to regulate acidity, in the manufacture of alcoholic beverages and syrups in the food industry;
- for leather processing in light industry;
- when treating non-potable water;
- for optimization of oil wells in the oil industry;
- in radio engineering and electronics.
Hydrochloric acid (HCl) in medicine
The most famous property of a hydrochloric acid solution is the alignment of the acid-base balance in the human body. A weak solution, or drugs, treats low acidity of the stomach. This optimizes the digestion of food, helps fight germs and bacteria that enter from the outside. Chemically pure hydrochloric acid helps to normalize the low level of gastric acidity and optimizes the digestion of proteins.
Oncology uses HCl to treat neoplasms and slow their progression. Hydrochloric acid preparations are prescribed for the prevention of stomach cancer, rheumatoid arthritis, diabetes, asthma, urticaria, cholelithiasis and others. In folk medicine, hemorrhoids are treated with a weak acid solution.
You can learn more about the properties and types of hydrochloric acid.
Like acids. The education program provides for the memorization by students of the names and formulas of six representatives of this group. And, looking through the table provided by the textbook, you notice in the list of acids the one that comes first and interested you in the first place - hydrochloric acid. Alas, in the classroom at school, neither the property nor any other information about it is studied. Therefore, those who are eager to gain knowledge outside the school curriculum are looking for additional information in all sorts of sources. But often, many do not find the information they need. And so the topic of today's article is dedicated to this particular acid.
Definition
Hydrochloric acid is a strong monobasic acid. In some sources, it may be called hydrochloric and hydrochloric, as well as hydrogen chloride.
Physical propertiesIt is a colorless and fuming caustic liquid in the air (photo on the right). However, technical acid has a yellowish color due to the presence of iron, chlorine and other additives in it. Its largest concentration at a temperature of 20 ° C is 38%. The density of hydrochloric acid with such parameters is 1.19 g/cm 3 . But this compound in varying degrees of saturation has completely different data. With a decrease in concentration, the numerical value of molarity, viscosity and melting point decrease, but the specific heat capacity and boiling point increase. Solidification of hydrochloric acid of any concentration gives various crystalline hydrates.
Chemical properties
All metals that come before hydrogen in the electrochemical series of their voltage can interact with this compound, forming salts and releasing hydrogen gas. If they are replaced by metal oxides, then the reaction products will be soluble salt and water. The same effect will be in the interaction of hydrochloric acid with hydroxides. If, however, any metal salt (for example, sodium carbonate) is added to it, the residue of which was taken from a weaker acid (carbonic), then chloride of this metal (sodium), water and gas corresponding to the acid residue (in this case, carbon dioxide) are formed. .
Receipt
The compound now discussed is formed when hydrogen chloride gas, which can be obtained by burning hydrogen in chlorine, is dissolved in water. Hydrochloric acid, which was obtained using this method, is called synthetic. Off-gases can also serve as a source for obtaining this substance. And such hydrochloric acid will be called off-gas. Recently, the level of production of hydrochloric acid using this method is much higher than its production by a synthetic method, although the latter gives the compound in a purer form. These are all ways of getting it in industry. However, in laboratories, hydrochloric acid is obtained in three ways (the first two differ only in temperature and reaction products) using various types of chemical interactions, such as:
- Effect of saturated sulfuric acid on sodium chloride at 150°C.
- The interaction of the above substances under conditions with a temperature of 550 ° C and above.
- Hydrolysis of aluminum or magnesium chlorides.
Hydrometallurgy and electroforming cannot do without the use of hydrochloric acid, where it is needed, in order to clean the surface of metals during tinning and soldering and to obtain chlorides of manganese, iron, zinc and other metals. In the food industry, this compound is known as food additive E507 - there it is an acidity regulator necessary in order to make seltzer (soda) water. Concentrated hydrochloric acid is also found in the gastric juice of any person and helps to digest food. During this process, its degree of saturation decreases, because. this composition is diluted with food. However, with prolonged fasting, the concentration of hydrochloric acid in the stomach gradually increases. And since this compound is very caustic, it can lead to stomach ulcers.
Conclusion
Hydrochloric acid can be both beneficial and harmful to humans. Its contact with the skin leads to the appearance of severe chemical burns, and the vapors of this compound irritate the respiratory tract and eyes. But if you handle this substance carefully, it can come in handy more than once in
Hydrochloric acid
Chemical properties
Hydrochloric acid, hydrogen chloride or hydrochloric acid - solution Hcl in water. According to Wikipedia, the substance belongs to the group of inorganic strong monobasic to-t. The full name of the compound in Latin: hydrochloric acid.
Formula of hydrochloric acid in chemistry: HCl. In a molecule, hydrogen atoms combine with halogen atoms - Cl. If we consider the electronic configuration of these molecules, it can be noted that the compounds take part in the formation of molecular orbitals 1s-hydrogen orbitals and both 3s And 3p-orbitals of an atom Cl. In the chemical formula of hydrochloric acid 1s-, 3s- And 3p-atomic orbitals overlap and form 1, 2, 3 orbitals. Wherein 3s-orbital is not binding. There is a shift of the electron density to the atom Cl and the polarity of the molecule decreases, but the binding energy of molecular orbitals increases (if we consider it along with other hydrogen halides ).
Physical properties of hydrogen chloride. It is a clear, colorless liquid that smokes when exposed to air. Molar mass of a chemical compound = 36.6 grams per mole. Under standard conditions, at an air temperature of 20 degrees Celsius, the maximum concentration of a substance is 38% by weight. The density of concentrated hydrochloric acid in this kind of solution is 1.19 g/cm³. In general, physical properties and characteristics such as density, molarity, viscosity, heat capacity, boiling point and pH, strongly depend on the concentration of the solution. These values are discussed in more detail in the table of densities. For example, the density of Hydrochloric Acid 10% = 1.048 kg per liter. When solidified, the substance forms crystalline hydrates different compositions.
Chemical properties of hydrochloric acid. What does hydrochloric acid react with? The substance interacts with metals that stand in front of hydrogen in a series of electrochemical potentials (iron, magnesium, zinc, and others). In this case, salts are formed and gaseous H. Lead, copper, gold, silver and other metals to the right of hydrogen do not react with hydrochloric acid. The substance reacts with metal oxides producing water and a soluble salt. Sodium hydroxide under the action of to-you forms and water. The neutralization reaction is characteristic of this compound.
Dilute Hydrochloric Acid reacts with metal salts, which are formed by weaker acids. For example, propionic acid weaker than salt. The substance does not react with stronger acids. And sodium carbonate will form after reaction with HCl chloride, carbon monoxide and water.
For a chemical compound, reactions with strong oxidizing agents are characteristic, with manganese dioxide , potassium permanganate : 2KMnO4 + 16HCl = 5Cl2 + 2MnCl2 + 2KCl + 8H2O. The substance reacts with ammonia , which produces thick white smoke, which consists of very fine crystals of ammonium chloride. The mineral pyrolusite also reacts with hydrochloric acid, as it contains manganese dioxide : MnO2+4HCl=Cl2+MnO2+2H2O(oxidation reaction).
There is a qualitative reaction to hydrochloric acid and its salts. When a substance interacts with silver nitrate a white precipitate silver chloride and formed nitric acid . Interaction reaction equation methylamine with hydrogen chloride looks like this: HCl + CH3NH2 = (CH3NH3)Cl.
A substance reacts with a weak base aniline . After dissolving aniline in water, hydrochloric acid is added to the mixture. As a result, the base dissolves and forms aniline hydrochloride (phenylammonium chloride ): (С6Н5NH3)Cl. The reaction of interaction of aluminum carbide with hydrochloric acid: Al4C3+12HCL=3CH4+4AlCl3. Reaction equation potassium carbonate with which it looks like this: K2CO3 + 2HCl = 2KCl + H2O + CO2.
Getting hydrochloric acid
To obtain synthetic hydrochloric acid, hydrogen is burned in chlorine, and then the resulting gaseous hydrogen chloride is dissolved in water. It is also common to produce a reagent from off-gases, which are formed as by-products during the chlorination of hydrocarbons (off-gas Hydrochloric Acid). In the production of this chemical compound, GOST 3118 77- for reagents and GOST 857 95– for technical synthetic hydrochloric acid.
In the laboratory, you can use a long-standing method in which table salt is exposed to concentrated sulfuric acid. Also, the agent can be obtained using the hydrolysis reaction aluminum chloride or magnesium . During the reaction, oxychlorides variable composition. To determine the concentration of a substance, standard titers are used, which are available in sealed ampoules, so that later it is possible to obtain a standard solution of a known concentration and use it to determine the quality of another titrant.
The substance has a fairly wide scope:
- it is used in hydrometallurgy, pickling and pickling;
- when cleaning metals during tinning and soldering;
- as a reagent for obtaining manganese chloride , zinc, iron and other metals;
- in the manufacture of mixtures with surfactants for cleaning metal and ceramic products from infection and dirt (inhibited hydrochloric acid is used);
- as an acidity regulator E507 in the food industry, as part of soda water;
- in medicine with insufficient acidity of gastric juice.
This chemical compound has a high hazard class - 2 (according to GOST 12L.005). When working with acid, special skin and eye protection. Sufficiently caustic substance in contact with the skin or inhalation causes chemical burns. To neutralize it, alkali solutions are used, most often baking soda. Hydrogen chloride vapor forms a caustic mist with water molecules in the air, which irritates the respiratory tract and eyes. If the substance reacts with bleach, potassium permanganate and other oxidizing agents, then a toxic gas, chlorine, is formed. On the territory of the Russian Federation, the circulation of Hydrochloric Acid with a concentration of more than 15% is limited.
pharmachologic effect
Increases the acidity of gastric juice.
Pharmacodynamics and pharmacokinetics
What is gastric acidity? This is a characteristic of the concentration of hydrochloric acid in the stomach. Acidity is expressed in pH. Normally, acid should be produced in the composition of gastric juice and take an active part in the processes of digestion. Formula of hydrochloric acid: HCl. It is produced by parietal cells located in the fundic glands, with the participation of H+/K+-ATPase . These cells line the fundus and body of the stomach. The acidity of gastric juice itself is variable and depends on the number of parietal cells and the intensity of the processes of neutralization of the substance by the alkaline components of gastric juice. Concentration produced to - you are stable and equal to 160 mmol/l. A healthy person should normally produce no more than 7 and at least 5 mmol of a substance per hour.
With insufficient or excessive production of Hydrochloric Acid, diseases of the digestive tract occur, the ability to absorb certain microelements, such as iron, deteriorates. The drug stimulates the secretion of gastric juice, reduces pH. Activates pepsinogen , converts it into an active enzyme pepsin . The substance has a beneficial effect on the acid reflex of the stomach, slows down the transition of incompletely digested food into the intestines. The processes of fermentation of the contents of the digestive tract slow down, pain and belching disappear, iron is better absorbed.
After oral administration, the drug is partially metabolized by saliva and gastric mucus, the contents of the duodenum 12. The unbound substance penetrates into the duodenum, where it is completely neutralized by its alkaline contents.
Indications for use
The substance is part of synthetic detergents, a concentrate for rinsing the oral cavity for the care of contact lenses. Diluted Hydrochloric Acid is prescribed for diseases of the stomach, accompanied by low acidity, with hypochromic anemia in combination with iron preparations.
Contraindications
The medicine should not be used for allergies on a synthetic substance, with diseases of the digestive tract associated with high acidity, with.
Side effects
Concentrated Hydrochloric Acid can cause severe burns if it comes into contact with the skin, eyes or respiratory tract. As part of various lek. preparations use a diluted substance, with prolonged use of large dosages, a deterioration in the condition of tooth enamel may occur.
Instructions for use (Method and dosage)
Hydrochloric acid is used in accordance with the instructions.
Inside the medicine is prescribed, previously dissolved in water. Usually use 10-15 drops of the drug in half a glass of liquid. The medicine is taken with meals, 2-4 times a day. The maximum single dosage is 2 ml (about 40 drops). Daily dose - 6 ml (120 drops).
Overdose
Cases of overdose are not described. With uncontrolled intake of the substance inside in large quantities, ulcers and erosions occur in the digestive tract. You should seek help from a doctor.
Interaction
The substance is often used in combination with pepsin and other medicines. drugs. The chemical compound in the digestive tract interacts with bases and some substances (see chemical properties).
special instructions
When treating with hydrochloric acid preparations, it is necessary to strictly adhere to the recommendations in the instructions.
Preparations containing (Analogues)
Coincidence in the ATX code of the 4th level:
For industrial purposes, inhibited hydrochloric acid (22-25%) is used. For medical purposes, the solution is used: Hydrochloric acid diluted . The substance is also contained in a concentrate for rinsing the mouth. Parontal , in soft contact lens care solution Biotru .
Description of the substance
Hydrochloric acid is an aqueous solution of hydrogen chloride. The chemical formula of this substance is HCl. In water, the mass of hydrogen chloride at the highest concentration cannot exceed 38%. At room temperature, hydrogen chloride is in a gaseous state. To pass it into a liquid state, it must be cooled to minus 84 degrees Celsius, in solid - to minus 112 degrees. The density of concentrated acid at room temperature is 1.19 g/cm 3 . This liquid is part of the gastric juice, which ensures the digestion of food. In this state, its concentration does not exceed 0.3%.Properties of hydrochloric acid
A solution of hydrogen chloride is chemically harmful, its hazard class is the second.
Hydrochloric liquid is a strong monobasic acid that can react with many metals, their salts, oxides and hydroxides, it can react with silver nitrate, ammonia, calcium hypochlorite and strong oxidizing agents:
Physical properties and effects on the body
At high concentrations, it is a caustic substance that can cause burns not only to the mucous membranes, but also to the skin. You can neutralize it with a solution of baking soda. When containers with a concentrated brine solution are opened, its vapors, in contact with moisture in the air, form a condensate of toxic vapors in the form of tiny droplets (aerosol), which irritates the respiratory tract and eyes.
The concentrated substance has a characteristic pungent odor. Technical grades of hydrogen chloride solution are divided into:
red unrefined, its color is mainly due to impurities of ferric chloride;
purified, colorless liquid, in which the concentration of HCl is about 25%;
fuming, concentrated, liquid with HCl concentration of 35-38%.
Chemical properties
How to receive
The process of production of saline liquid consists of the stages of obtaining hydrogen chloride and absorption (absorption) of it with water.
Exists three industrial ways production of hydrogen chloride:
synthetic
sulfate
from side gases (off-gases) of a number of technological processes. The last method is the most common. By-product HCl is usually formed during the dehychlorination and chlorination of organic compounds, the manufacture of potash fertilizers, the pyrolysis of metal chlorides or organic waste containing chlorine.
Storage and transportation
Industrial hydrochloric acid is stored and transported in specialized polymer-coated tanks and containers, polyethylene barrels, glass bottles packed in boxes. Hatches of containers and tanks, corks of barrels and bottles must ensure the tightness of the container. The acid solution should not come into contact with metals that are in the voltage line to the left of hydrogen, as this can cause explosive mixtures.
Application
in metallurgy for the extraction of ores, removal of rust, scale, dirt and oxides, soldering and tinning;
in the manufacture of synthetic rubbers and resins;
in electroplating;
as an acidity regulator in the food industry;
to obtain metal chlorides;
to obtain chlorine;
in medicine for the treatment of insufficient acidity of gastric juice;
as a cleaner and disinfectant.
What is hydrochloric acid solution? It is a compound of water (H2O) and hydrogen chloride (HCl), which is a colorless thermal gas with a characteristic odor. Chlorides are highly soluble and decompose into ions. Hydrochloric acid is the most well-known compound that forms HCl, so we can talk about it and its features in detail.
Description
Hydrochloric acid solution belongs to the class of strong. It is colorless, transparent and caustic. Although technical hydrochloric acid has a yellowish color due to the presence of impurities and other elements. It "smokes" in the air.
It is worth noting that this substance is also present in the body of every person. In the stomach, to be more precise, at a concentration of 0.5%. Interestingly, this amount is enough to completely destroy the razor blade. The substance will corrode it in just a week.
Unlike the same sulfuric acid, by the way, the mass of hydrochloric acid in solution does not exceed 38%. We can say that this indicator is a “critical” point. If you start to increase the concentration, then the substance will simply evaporate, as a result of which hydrogen chloride will simply evaporate with water. Plus, this concentration is maintained only at 20 ° C. The higher the temperature, the faster the evaporation.
Interaction with metals
Hydrochloric acid solution can enter into many reactions. First of all, with metals that stand before hydrogen in a series of electrochemical potentials. This is the sequence in which the elements go as their characteristic measure, the electrochemical potential (φ 0), increases. This indicator is extremely important in the cation reduction half-reactions. In addition, it is this series that demonstrates the activity of metals, which they exhibit in redox reactions.
So, interaction with them occurs with the release of hydrogen in the form of gas and with the formation of salt. Here is an example of a reaction with sodium, a soft alkali metal: 2Na + 2HCl → 2NaCl + H 2 .
With other substances, the interaction proceeds according to similar formulas. This is how the reaction with aluminum, a light metal, looks like: 2Al + 6HCl → 2AlCl 3 + 3H 2.
Reactions with oxides
Hydrochloric acid solution also interacts well with these substances. Oxides are binary compounds of an element with oxygen, having an oxidation state of -2. All known examples are sand, water, rust, dyes, carbon dioxide.
Hydrochloric acid does not interact with all compounds, but only with metal oxides. The reaction also produces a soluble salt and water. An example is the process that occurs between acid and magnesium oxide, an alkaline earth metal: MgO + 2HCl → MgCl 2 + H 2 O.
Reactions with hydroxides
This is the name of inorganic compounds in the compositions of which there is a hydroxyl group -OH, in which the hydrogen and oxygen atoms are connected by a covalent bond. And, since the hydrochloric acid solution only interacts with metal hydroxides, it is worth mentioning that some of them are called alkalis.
So the resulting reaction is called neutralization. Its result is the formation of a weakly dissociating substance (i.e. water) and salt.
An example is the reaction of a small volume of hydrochloric acid solution and barium hydroxide, a soft alkaline earth malleable metal: Ba(OH) 2 + 2HCl = BaCl 2 + 2H 2 O.
Interaction with other substances
In addition to the above, hydrochloric acid can also react with other types of compounds. In particular with:
- Metal salts, which are formed by other, weaker acids. Here is an example of one of these reactions: Na 2 Co 3 + 2HCl → 2NaCl + H 2 O + CO 2. Shown here is the interaction with a salt formed by carbonic acid (H 2 CO 3).
- Strong oxidizers. With manganese dioxide, for example. Or with potassium permanganate. These reactions are accompanied by the release of chlorine. Here is one example: 2KMnO 4 + 16HCl → 5Cl 2 + 2MnCl 2 + 2KCl + 8H 2 O.
- ammonia. It is hydrogen nitride with the formula NH 3 , which is a colorless but pungent gas. The consequence of its reaction with a solution of hydrochloric acid is a mass of thick white smoke, consisting of small crystals of ammonium chloride. Which, by the way, is known to everyone as ammonia (NH 4 Cl). The interaction formula is as follows: NH 3 + HCl → NH 4 CL.
- Silver nitrate - an inorganic compound (AgNO 3), which is a salt of nitric acid and silver metal. Due to the contact of a solution of hydrochloric acid with it, a qualitative reaction occurs - the formation of a cheesy precipitate of silver chloride. which does not dissolve in nitric acid. It looks like this: HCL + AgNO 3 → AgCl ↓ + HNO 3.
Getting a substance
Now we can talk about what they do to form hydrochloric acid.
First, by burning hydrogen in chlorine, the main component, gaseous hydrogen chloride, is obtained. which is then dissolved in water. The result of this simple reaction is the formation of a synthetic acid.
This substance can also be obtained from off-gases. These are chemical waste (side) gases. They are formed by a variety of processes. For example, when chlorinating hydrocarbons. The hydrogen chloride in their composition is called off-gas. And the acid thus obtained, respectively.
It should be noted that in recent years the share of the off-gas substance in the total volume of its production has been increasing. And the acid formed as a result of burning hydrogen in chlorine is displaced. However, in fairness, it should be noted that it contains fewer impurities.
Application in everyday life
Many cleaning products that householders use regularly contain a certain amount of hydrochloric acid solution. 2-3 percent, and sometimes less, but it's there. That is why, putting plumbing in order (washing tiles, for example), you need to wear gloves. Highly acid products can harm the skin.
Another solution is used as a stain remover. It helps to get rid of ink or rust on clothes. But in order for the effect to be noticeable, it is necessary to use a more concentrated substance. A 10% hydrochloric acid solution will do. He, by the way, perfectly removes scale.
It is important to store the substance correctly. Keep acid in glass containers and in places where animals and children cannot reach. Even a weak solution that gets on the skin or mucous membranes can cause a chemical burn. If this happens, immediately rinse the areas with water.
In the field of construction
The use of hydrochloric acid and its solutions is a popular way to improve many building processes. For example, it is often added to concrete mix to increase frost resistance. In addition, this way it hardens faster, and the resistance of the masonry to moisture increases.
Hydrochloric acid is also used as a limestone cleaner. Its 10% solution is the best way to deal with dirt and marks on red brick. It is not recommended to use it for cleaning others. The structure of other bricks is more sensitive to the action of this substance.
In medicine
In this area, the substance under consideration is also actively used. Dilute hydrochloric acid has the following effects:
- Digests proteins in the stomach.
- Stops the development of malignant tumors.
- Helps in the treatment of cancer.
- Normalizes acid-base balance.
- Serves as an effective tool in the prevention of hepatitis, diabetes, psoriasis, eczema, rheumatoid arthritis, cholelithiasis, rosacea, asthma, urticaria and many other ailments.
Did you come up with the idea to dilute the acid and use it inside in this form, and not as part of medicines? This is practiced, but it is strictly forbidden to do this without medical advice and instructions. Having calculated the proportions incorrectly, you can swallow an excess of hydrochloric acid solution, and simply burn your stomach.
By the way, you can still take medications that stimulate the production of this substance. And not just chemicals. The same calamus, peppermint and wormwood contribute to this. You can make decoctions based on them yourself, and drink them for prevention.
Burns and poisoning
As effective as this remedy is, it is dangerous. Hydrochloric acid, depending on the concentration, can cause chemical burns of four degrees:
- There is only redness and pain.
- There are blisters with a clear liquid and swelling.
- Formed necrosis of the upper layers of the skin. Blisters fill with blood or cloudy contents.
- The lesion reaches the tendons and muscles.
If the substance somehow got into the eyes, it is necessary to rinse them with water, and then with a soda solution. But in any case, the first thing to do is to call an ambulance.
The ingestion of acid inside is fraught with acute pains in the chest and abdomen, swelling of the larynx, vomiting bloody masses. As a result, severe pathologies of the liver and kidneys.
And the first signs of poisoning in pairs include a dry frequent cough, choking, damage to the teeth, burning in the mucous membranes and abdominal pain. The first emergency aid is washing and rinsing the mouth with water, as well as access to fresh air. Only a toxicologist can provide real help.
