Hydrochloric acid reacts with oxygen. Hydrochloric acid: properties, production, application
Structural formula
True, empirical, or gross formula: HCl
Chemical composition of hydrochloric acid
Molecular mass: 36.461
Hydrochloric acid(also hydrochloric acid, hydrochloric acid, hydrogen chloride) - a solution of hydrogen chloride (HCl) in water, a strong monobasic acid. Colorless, transparent, caustic liquid, "fuming" in air (technical hydrochloric acid, yellowish due to impurities of iron, chlorine, etc.). At a concentration of about 0.5% it is present in the human stomach. The maximum concentration at 20 ° C is 38% by weight, the density of such a solution is 1.19 g / cm³. Molar mass 36.46 g / mol. Salts of hydrochloric acid are called chlorides.
Physical properties
The physical properties of hydrochloric acid strongly depend on the concentration of dissolved hydrogen chloride. When solidified, it gives crystalline hydrates of the compositions HCl · H 2 O, HCl · 2H 2 O, HCl · 3H 2 O, HCl · 6H 2 O.
Chemical properties
- Interaction with metals in the range of electrochemical potentials up to hydrogen, with the formation of salt and the evolution of hydrogen gas.
- Interaction with metal oxides to form soluble salt and water.
- Interaction with metal hydroxides with the formation of soluble salt and water (neutralization reaction).
- Interaction with metal salts formed by weaker acids, such as carbonic acid.
- Interaction with strong oxidants (potassium permanganate, manganese dioxide) with the release of gaseous chlorine.
- Interaction with ammonia with the formation of a thick white smoke, consisting of the smallest crystals of ammonium chloride.
- A qualitative reaction to hydrochloric acid and its salt is its interaction with silver nitrate, which forms a curdled precipitate of silver chloride, insoluble in nitric acid.
Receiving
Hydrochloric acid is obtained by dissolving gaseous hydrogen chloride in water. Hydrogen chloride is obtained by burning hydrogen in chlorine, the acid obtained in this way is called synthetic. Also, hydrochloric acid is obtained from offgas - by-gases formed during various processes, for example, during the chlorination of hydrocarbons. The hydrogen chloride contained in these gases is called off-gas, and the acid obtained in this way is called off-gas. In recent decades, the share of off-gas hydrochloric acid in the production volume has been gradually increasing, displacing the acid obtained by burning hydrogen in chlorine. But hydrochloric acid obtained by burning hydrogen in chlorine contains fewer impurities and is used when high purity is required. In laboratory conditions, a method developed by alchemists is used, which consists in the action of concentrated sulfuric acid on table salt. At temperatures above 550 ° C and excess sodium chloride, interaction is possible. It is possible to obtain by hydrolysis of magnesium and aluminum chlorides (the hydrated salt is heated). These reactions may not go to the end with the formation of basic chlorides (oxychlorides) of variable composition, for example. Hydrogen chloride is readily soluble in water. So, at 0 ° C, 1 volume of water can absorb 507 volumes of HCl, which corresponds to an acid concentration of 45%. However, with room temperature the solubility of HCl is lower, therefore, in practice, 36% hydrochloric acid is usually used.
Application
Industry
- It is used in hydrometallurgy and electroplating (etching, pickling), for cleaning the surface of metals during soldering and tinning, for obtaining chlorides of zinc, manganese, iron and other metals. In a mixture with surfactants, it is used to clean ceramic and metal products (inhibited acid is needed here) from contamination and disinfection.
- Registered in the food industry as an acidity regulator (food additive E507). It is used for making seltzer (soda) water.
The medicine
- A natural constituent of human gastric juice. At a concentration of 0.3-0.5%, usually in a mixture with the enzyme pepsin, it is administered orally with insufficient acidity.
Features of treatment
Highly concentrated hydrochloric acid is a caustic substance that causes severe chemical burns when in contact with the skin. Eye contact is especially dangerous. A weak alkali solution, usually baking soda, is used to neutralize burns. When the vessels with concentrated hydrochloric acid are opened, hydrogen chloride vapors, attracting moisture in the air, form a fog that irritates the eyes and respiratory tract of a person. Reacts with strong oxidants (bleach, manganese dioxide, potassium permanganate) to form toxic chlorine gas. In the Russian Federation, the turnover of hydrochloric acid with a concentration of 15% or more is limited.
- (HCl), an aqueous solution of hydrogen chloride, a colorless gas with a pungent odor. It is obtained by the action of sulfuric acid on table salt, as a by-product of the chlorination of hydrocarbons, or by the reaction of hydrogen and chlorine. Hydrochloric acid is used for ... ... Scientific and technical encyclopedic dictionary
Hydrochloric acid- - HCl (HCl) (hydrochloric acid, hydrochloric acid, hydrogen chloride) is a solution of hydrogen chloride (HCl) in water, antifreeze additive. It is a colorless liquid with a pungent odor, without suspended particles. ... ... Encyclopedia of terms, definitions and explanations of building materials
- (hydrochloric acid) solution of hydrogen chloride in water; strong acid. Colorless liquid fuming in air (technical hydrochloric acid is yellowish due to impurities of Fe, Cl2, etc.). Maximum concentration (at 20 .C) 38% by weight, ... ... Big Encyclopedic Dictionary
HYDROCHLORIC ACID- (Acidum muriaticum, Acid, hydrochloricum), a solution of hydrogen chloride (HC1) in water. In nature, it is found in the water of certain sources of volcanic origin, and is also found in gastric juice (up to 0.5%). Hydrogen chloride can be obtained ... Great medical encyclopedia
HYDROCHLORIC ACID- (hydrochloric acid, hydrochloric acid) a strong monobasic volatile acid with a pungent odor, an aqueous solution of hydrogen chloride; the maximum concentration is 38% by weight, the density of such a solution is 1.19 g / cm3. Applied in ... ... Russian encyclopedia of labor protection
HYDROCHLORIC ACID- (hydrochloric acid) HCl aqueous solution of hydrogen chloride, strong monobasic acid, volatile, with a pungent odor; iron and chlorine impurities paint it yellowish. Concentrated sulfuric acid that goes on sale contains 37% ... ... Big Polytechnic Encyclopedia
Sush., Number of synonyms: 1 acid (171) ASIS Synonym Dictionary. V.N. Trishin. 2013 ... Synonym dictionary
Modern encyclopedia
Hydrochloric acid- HYDRAULIC ACID, an aqueous solution of hydrogen chloride HCl; liquid fuming in the air with a pungent odor. Hydrochloric acid is used to obtain various chlorides, etching metals, processing ores, in the production of chlorine, soda, rubbers, etc. ... ... Illustrated Encyclopedic Dictionary
- (hydrochloric acid), a solution of hydrogen chloride in water; strong acid. Colorless liquid "fuming" in the air (technical hydrochloric acid is yellowish due to impurities of Fe, Cl2, etc.). Maximum concentration (at 20 ° C) 38% by mass, ... ... encyclopedic Dictionary
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- Stories, Mikhail Prishvin. Prishvin Mikhail Mikhailovich (1873-1954) - Prishvin Mikhail Mikhailovich (1873-1954) - Russian writer, whose philosophical and lyrical prose is associated mainly with themes of nature, with folk life and ... an audiobook
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Properties of hydrochloric acid
A solution of hydrogen chloride is chemically harmful, its hazard class is the second.
Salt liquid is a strong monobasic acid that can react with many metals, their salts, oxides and hydroxides, it can interact with silver nitrate, ammonia, calcium hypochlorite and strong oxidants:
Physical properties and effects on the body
At high concentrations, it is a caustic substance that can cause burns not only of the mucous membranes, but also of the skin. You can neutralize it with a baking soda solution. When containers with a concentrated saline solution are opened, its vapors, in contact with the moisture in the air, form a condensation of poisonous 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 the admixtures 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 do you get
The process of producing a saline liquid consists of the stages of obtaining hydrogen chloride and its absorption (absorption) by water.
Exists three industrial methods obtaining hydrogen chloride:
synthetic
sulfate
from by-gases (offgas) of a number of technological processes. The last method is the most common. By-product HCl is usually formed during the dechlorination and chlorination of organic compounds, the manufacture of potash fertilizers, the pyrolysis of metal chlorides or organic waste containing chlorine.
Storage and transportation
The technical 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 acidic solution should not come into contact with metals located in the voltage line to the left of hydrogen, as this can cause the formation of 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;
for the production of metal chlorides;
for chlorine production;
in medicine for the treatment of insufficient acidity of gastric juice;
as a cleaning and disinfecting agent.
Hydrochloric acid is one of the strongest and most dangerous substances for humans on the list of hazardous chemicals. However, it is surprising that it exists in the body of every person: hydrochloric acid is an integral part of gastric juice and plays important role in the processes of digestion. In an amount of 0.2%, it promotes the transition of food masses from the stomach to the duodenum and neutralizes microbes that enter the stomach from the external environment. It also activates the enzyme pepsinogen, is involved in the formation of secretin and some other hormones that stimulate the activity of the pancreas. For this purpose, it is used in medicine, prescribing its solution to patients to increase the acidity of gastric juice. In general, hydrochloric acid is widely used in our life. For example, in the heavy industry - for the production of chlorides of various metals, in the textile industry - for the production of synthetic dyes; for the food industry, acetic acid is made from it, for the pharmaceutical industry - activated carbon. It is also found in various adhesives and hydrolysis alcohol. It is used for etching metals, cleaning various vessels, casing of boreholes from carbonates, oxides and other sediments and contaminants. In metallurgy, ores are processed with hydrochloric acid, in the leather industry - leather before tanning and dyeing. Hydrochloric acid is transported in glass bottles or gummed (covered with a layer of rubber) metal containers, as well as in polyethylene containers.
What is it as a chemical?
Hydrochloric acid, or hydrochloric acid, is an aqueous solution of hydrogen chloride HCl, which is a clear, colorless liquid with a pungent odor of hydrogen chloride. The technical type of acid has a yellowish-green color due to admixtures of chlorine and iron salts. The maximum concentration of hydrochloric acid is about 36% HCl; such a solution has a density of 1.18 g / cm3. Concentrated acid "smokes" in air, since the evolved gaseous HCl forms tiny droplets of hydrochloric acid with water vapor.
Despite this characteristic, when in contact with air, hydrochloric acid is not flammable and not explosive. But at the same time, it is one of the strongest acids and dissolves (with the release of hydrogen and the formation of salts - chlorides) all metals that stand in the series of voltages up to hydrogen. Chlorides are also formed by the interaction of hydrochloric acid with metal oxides and hydroxides. With strong oxidants, it behaves like a reducing agent.
Salts of hydrochloric acid are chlorides and, with the exception of AgCl, Hg2Cl2, are readily soluble in water. Materials such as glass, ceramics, porcelain, graphite, fluoroplastic are resistant to hydrochloric acid.
Hydrochloric acid of hydrogen chloride in water is obtained, which, in turn, is either directly synthesized from hydrogen and chlorine, or is obtained by the action of sulfuric acid on sodium chloride.
The industrially produced (technical) hydrochloric acid has a strength of at least 31% HCl (synthetic) and 27.5% HCl (from NaCI). Commercial acid is called concentrated if it contains 24% or more HCl; if the HCl content is less, then the acid is called dilute.
Hydrochloric acid is a homogeneous colorless liquid with a pungent odor. It is a very corrosive substance that interacts with most metals. Due to these properties, the material is widely used not only in industry, but also in everyday life.
The reagent is part of various means for getting rid of sewer blockages, but it can be used for this purpose on its own, after being diluted with water in the required proportions.
The use of an acid solution in the house is not limited to this: the material is used to clean plumbing fixtures from rust and limescale, to remove stubborn stains from fabrics, and even to remove scale in a teapot.
Precautionary measures
Since the reagent is highly corrosive and emits toxic fumes when interacting with air, it is very important to use protective equipment when working with it.
When it comes into contact with the skin and mucous membranes, the material causes chemical burns, and with prolonged exposure to the HCl atmosphere, teeth decay, the development of catarrh of the respiratory tract and ulceration of the nasal mucosa.
For protection, you must use a gas mask, a rubberized apron, goggles and rubber gloves. Carry out work only in well-ventilated areas. If the reagent comes in contact with the skin or mucous membranes, rinse the affected area large quantity running water and seek medical attention.
How to get rid of blockages?
Diluted hydrochloric acid should be used for the tough and targeted cleaning of the sewage system from organic deposits (fats, food residues, hair, detergents, etc.). This method is not suitable for steel, iron and plastic pipes, as the connection can lead to corrosion and even the formation of through holes.
Before starting the procedure, you need to close the drain holes in other plumbing and ensure the flow of air into the room. This step is necessary because the acid will actively generate toxic gases during operation.
It is recommended to dilute the composition with water until a concentration of 3-10% is reached, then pour it directly into the sewer and leave for 1-2 hours. Then you need to flush the pipes with plenty of water and, if necessary, repeat the procedure.
An important point! Do not mix the reagent with other sewer cleaners, especially those based on alkalis. Otherwise, the reaction of these connections will result in severe damage to the pipes.
Other household uses of acid
With an acidic composition, you can easily clean plumbing from faience from limescale and rust, remove urinary tartar and other contaminants. For a greater effect, an inhibitor (for example, urotropine) is added to the agent, which slows down the chemical reaction.
The procedure is carried out as follows: the acid is diluted with water until a 5% concentration is reached, and an inhibitor is added at the rate of 0.5 g per 1 liter of liquid. The resulting composition is treated with the surface and left for 30-40 minutes (depending on the degree of contamination), after which it is washed with water.
A mild acidic solution is also used to remove berry stains, ink or rust from fabrics. To do this, the material is soaked in the composition for a while, after which it is thoroughly rinsed and washed as usual.
Kettle descaling
For this purpose, a 3-5% solution of hydrochloric acid is used, which is poured into a kettle and heated to 60-80 ° C for 1-2 hours or until the scale deposits disintegrate. After that, the scale becomes loose and can be easily removed with a wooden spatula.
The effectiveness of the method is due to the fact that the reagent reacts with magnesium and calcium carbonates and converts them into soluble salts. The carbon dioxide released during this process destroys the scale layer and makes it friable. After removing the salt deposits, the dishes are thoroughly washed with clean water.
An important point! This method is not suitable for descaling enamelled or aluminum teapots with chips or cracks: this will corrode the metal and severely damage it.
Conclusion
Subject to precautions and safety rules, hydrochloric acid will become an irreplaceable assistant in everyday life. And you can buy it at the most affordable prices in our company.
