HYDROCHLORIC ACID

Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl).
Hydrochloric acid is a colorless solution with a distinctive pungent smell.
Hydrochloric acid is classified as a strong acid.
Hydrochloric acid is a component of the gastric acid in the digestive systems of most animal species, including humans.
Hydrochloric acid is an important laboratory reagent and industrial chemical.

IUPAC name: Chlorane
CAS Number: 7647-01-0
EC Number: 231-595-7
Chemical formula: HCl

Other names of Hydrochloric acid:, hydrochloric acid, hydrogen chloride, 7647-01-0, Muriatic acid, chlorane, Chlorohydric acid, Acide chlorhydrique, Anhydrous hydrochloric acid, Chlorwasserstoff, Muriaticum acidum, Chloorwaterstof, Chlorowodor, Acido cloridrico, Bowl Cleaner, chlorure d'hydrogene, Hydrogenchlorid, 4-D Bowl Sanitizer, Emulsion Bowl Cleaner, Caswell No. 486, monohydrochloride, Baume hcl, Icon etch, Acido clorhidrico, Aqueous hydrogen chloride, Enplate po 236, Chloruro de hidrogeno, Hydrochloric acid gas, NSC 77365, HSDB 545, chloridohydrogen, CHEBI:17883, Marine acid, Wasserstoffchlorid, Chlorure d'hydrogene anhydre, Cloruro de hidrogeno anhidro, Hydrochloric acid, anhydrous, UNII-QTT17582CB, NSC-77365, cloruro de hidrogeno, Acidum hydrochloricum, EPA Pesticide Chemical Code 045901, INS NO.507, QTT17582CB, HCl, INS-507, [HCl], Hydrogen chloride, anhydrous, DTXSID2020711, E-507, EC 231-595-7, MFCD00011324, E507, Acid, Muriatic, mono hydrochloride, Acid, Hydrochloric, UN1050, UN1789, UN2186, chlorum, hydochloride, hydrochlorie, hydrochoride, hydrocloride, Salzsaeure, hydro chloride, hydro-chloride, hydrogenchloride, Soldering acid, chlorhydric acid, hydochloric acid, hydogen chloride, hydrochoric acid, hydrocloric acid, hydrogen chlorid, hydrogen choride, hydrogen cloride, hyrochloric acid, hyrogen chloride, Liriopesides-B, AescinIIB, hvdrochloric acid, hvdrogen chloride, hydorchloric acid, hydrochioric acid, hydrochloric aicd, hydrochloric-acid, hydrogen-chloride, hyrdochloric acid, Hydrochloric ccid, Acidum Muriaticum, monohydro-chloride, Sibiricose-A6, hydrogen ch1oride, hydro chloric acid, hydro-chloric acid, hydrochloric ac id, hydro- chloric acid, HEMMORHOIDS, Caswell No 486, trans-stilben-2-ylamine; hydrochloride, H-Cl, 17Cl, Hydrogen-chloride-anhydrous-, Acidum hydrochloricum dilutum, DTXCID20711, CHEMBL1231821, NSC77365, BDBM50499188, CS0072, MFCD00792839, AKOS015843726, CCG-221928, DB13366, NA 1789, UN 1050, UN 1789, UN 2186, 1082661-04-8, 2647-01-0, FT-0627124, FT-0628063, FT-0699355, FT-0699890, FT-0699899, FT-0700010, H1060, H1062, H1202, H1203, H1277, X0038, X0039, X0041, C01327, D02057, J-006148

Etymology
Because it was produced from rock salt according to the methods of Johann Rudolph Glauber, hydrochloric acid was historically called by European alchemists spirits of salt or acidum salis (salt acid).
Both names are still used, especially in other languages, such as German: Salzsäure, Dutch: Zoutzuur, Swedish: Saltsyra, Spanish: Salfumán, Turkish: Tuz Ruhu, Polish: kwas solny, Hungarian: sósav, Czech: kyselina solná, and Chinese: 盐酸 (yánsuān).

Gaseous HCl was called marine acid air.
The name muriatic acid has the same origin (muriatic means "pertaining to brine or salt", hence muriate means hydrochloride), and this name is still sometimes used.
The name hydrochloric acid was coined by the French chemist Joseph Louis Gay-Lussac in 1814.

History
9th–10th century
In the early tenth century, the Persian physician and alchemist Abu Bakr al-Razi (c. 865–925, Latin: Rhazes) conducted experiments with sal ammoniac (ammonium chloride) and vitriol (hydrated sulfates of various metals), which he distilled together, thus producing the gas hydrogen chloride.
In doing so, al-Razi may have stumbled upon a primitive method for producing hydrochloric acid, as perhaps manifested in the following recipe from his Kitāb al-Asrār ("The Book of Secrets"):

Take equal parts of sweet salt, Bitter salt, Ṭabarzad salt, Andarānī salt, Indian salt, salt of Al-Qilī, and salt of Urine.
After adding an equal weight of good crystallised Sal-ammoniac, dissolve by moisture, and distil (the mixture).
There will distil over a strong water, which will cleave stone (sakhr) instantly.

However, it appears that in most of his experiments al-Razi disregarded the gaseous products, concentrating instead on the color changes that could be effected in the residue.
According to Robert P. Multhauf, hydrogen chloride was produced many times without clear recognition that, by dissolving it in water, hydrochloric acid may be produced.

11th–13th century
Drawing on al-Razi's experiments, the De aluminibus et salibus ("On Alums and Salts"), an eleventh- or twelfth-century Arabic text falsely attributed to al-Razi and translated into Latin by Gerard of Cremona (1144–1187), described the heating of metals with various salts, which in the case of mercury resulted in the production of mercury(II) chloride (corrosive sublimate).

In this process, hydrochloric acid actually started to form, but it immediately reacted with the mercury to produce corrosive sublimate.
Thirteenth-century Latin alchemists, for whom the De aluminibus et salibus was one of the main reference works, were fascinated by the chlorinating properties of corrosive sublimate, and they soon discovered that when the metals are eliminated from the process of heating vitriols, alums, and salts, strong mineral acids can directly be distilled.

14th–15th century
Aqua regia
One important invention that resulted from the discovery of the mineral acids is aqua regia, a mixture of nitric acid and hydrochloric acid in a 1:3 proportion, capable of dissolving gold.
This was first described in pseudo-Geber's De inventione veritatis ("On the Discovery of Truth", after c. 1300), where aqua regia was prepared by adding ammonium chloride to nitric acid.

The fact that aqua regia typically is defined as a mixture of nitric acid and hydrochloric acid does not mean that hydrochloric acid was discovered before or simultaneously with aqua regia.
The isolation of hydrochloric acid happened about 300 years later.

The production of hydrochloric acid itself (i.e., as an isolated substance rather than as already mixed with nitric acid) depended on the use of more efficient cooling apparatus, which would only develop in subsequent centuries.

16th–17th century
Isolation of hydrochloric acid
From the point of view of Western history of chemistry, hydrochloric acid was the last of the three well-known mineral acids for which the method of its production appeared in the literature.
Recipes for its production started to appear in the late sixteenth century.

The earliest recipes for the production of hydrochloric acid are found in Giovanni Battista Della Porta's (1535–1615) Magiae naturalis ("Natural Magic") and in the works of other contemporary chemists like Andreas Libavius (c. 1550–1616), Jean Beguin (1550–1620), and Oswald Croll (c. 1563–1609).

Among the historians who have written about this are German chemists Hermann Franz Moritz Kopp (1845) and Edmund Oscar von Lippmann (1938), mining engineer (and future U.S. president) Herbert Hoover with his wife geologist Lou Henry Hoover (1912), Dutch chemist Robert Jacobus Forbes (1948), American chemist Mary Elvira Weeks (1956), and British chemists F. Sherwood Taylor (1957) and J. R. Partington (1960).
Italian chemist Ladislao Reti have summarized the result of their efforts thus:

The first clear instance of the preparation of hydrochloric acid appears in the writings of Della Porta, (1589 and 1608), Libavius (1597), pseudo-Basil (1604), van Helmont (1646) and Glauber (1648). Less convincing earlier references are found in the Plichto of Rosetti (1540) and in Agricola (1558).

As for the first practical method of preparation from vitriol and common salt, there is no doubt that pseudo-Basil precedes Glauber, but the latter has the unquestionable merit of having indicated the way of producing the acid later to be adopted by the chemical industry for large-scale operations.

Dissolving metals
The knowledge of mineral acids such as hydrochloric acid would be of key importance to seventeenth-century chemists like Daniel Sennert (1572–1637) and Robert Boyle (1627–1691), who used their capability to rapidly dissolve metals in their demonstrations of the composite nature of bodies.

Industrial developments
During the Industrial Revolution in Europe, demand for alkaline substances increased.
A new industrial process developed by Nicolas Leblanc of Issoudun, France enabled cheap large-scale production of sodium carbonate (soda ash).

In this Leblanc process, common salt is converted to soda ash, using sulfuric acid, limestone, and coal, releasing hydrogen chloride as a by-product.
Until the British Alkali Act 1863 and similar legislation in other countries, the excess HCl was often vented into the air.

An early exception was the Bonnington Chemical Works where, in 1830, the HCl began to be captured and the hydrochloric acid produced was used in making sal ammoniac (ammonium chloride).
After the passage of the act, soda ash producers were obliged to absorb the waste gas in water, producing hydrochloric acid on an industrial scale.

In the 20th century, the Leblanc process was effectively replaced by the Solvay process without a hydrochloric acid by-product.
Since hydrochloric acid was already fully settled as an important chemical in numerous applications, the commercial interest initiated other production methods, some of which are still used today.
After 2000, hydrochloric acid is mostly made by absorbing by-product hydrogen chloride from industrial organic compounds production.

Chemical properties
Gaseous hydrogen chloride is a molecular compound with a covalent bond between the hydrogen and chlorine atoms.
In aqueous solutions dissociation is complete, with the formation of chloride ions and hydrated hydrogen ions (hydronium ions).
A combined IR, Raman, X-ray, and neutron diffraction study of concentrated hydrochloric acid showed that the hydronium ion forms hydrogen bonded complexes with other water molecules.

The pKa value of hydrochloric acid in aqueous solution is estimated theoretically to be −5.9.
A solution of hydrogen chloride in water behaves as a strong acid: the concentration of HCl molecules is effectively zero.

Physical properties of hydrochloric acid, such as boiling and melting points, density, and pH, depend on the concentration or molarity of HCl in the aqueous solution.
They range from those of water at very low concentrations approaching 0% HCl to values for fuming hydrochloric acid at over 40% HCl.

Hydrochloric acid as the binary (two-component) mixture of HCl and H2O has a constant-boiling azeotrope at 20.2% HCl and 108.6 °C (381.8 K; 227.5 °F).
There are four constant-crystallization eutectic points for hydrochloric acid, between the crystal form of [H3O]Cl (68% HCl), [H5O2]Cl (51% HCl), [H7O3]Cl (41% HCl), [H3O]Cl·5H2O (25% HCl), and ice (0% HCl).
There is also a metastable eutectic point at 24.8% between ice and the [H7O3]Cl crystallization.
They are all hydronium salts.

Production
Hydrochloric acid is usually prepared industrially by dissolving hydrogen chloride in water.
Hydrogen chloride can be generated in many ways, and thus several precursors to hydrochloric acid exist.
The large-scale production of hydrochloric acid is almost always integrated with the industrial scale production of other chemicals, such as in the chloralkali process which produces hydroxide, hydrogen, and chlorine, the latter of which can be combined to produce HCl.

As the reaction is exothermic, the installation is called an HCl oven or HCl burner.
The resulting hydrogen chloride gas is absorbed in deionized water, resulting in chemically pure hydrochloric acid.
This reaction can give a very pure product, e.g. for use in the food industry.

Industrial market
Hydrochloric acid is produced in solutions up to 38% HCl (concentrated grade).
Higher concentrations up to just over 40% are chemically possible, but the evaporation rate is then so high that storage and handling require extra precautions, such as pressurization and cooling.

Bulk industrial-grade is therefore 30% to 35%, optimized to balance transport efficiency and product loss through evaporation.
In the United States, solutions of between 20% and 32% are sold as muriatic acid.
Solutions for household purposes in the US, mostly cleaning, are typically 10% to 12%, with strong recommendations to dilute before use.

In the United Kingdom, where it is sold as "Spirits of Salt" for domestic cleaning, the potency is the same as the US industrial grade.
In other countries, such as Italy, hydrochloric acid for domestic or industrial cleaning is sold as "Acido Muriatico", and its concentration ranges from 5% to 32%.

Major producers worldwide include Dow Chemical at 2 million tonnes annually (Mt/year), calculated as HCl gas, Georgia Gulf Corporation, Tosoh Corporation, Akzo Nobel, and Tessenderlo at 0.5 to 1.5 Mt/year each.
Total world production, for comparison purposes expressed as HCl, is estimated at 20 Mt/year, with 3 Mt/year from direct synthesis, and the rest as secondary product from organic and similar syntheses.
By far, most hydrochloric acid is consumed captively by the producer.
The open world market size is estimated at 5 Mt/year.

Applications
Hydrochloric acid is a strong inorganic acid that is used in many industrial processes such as refining metal.
The application often determines the required product quality.
Hydrogen chloride, not hydrochloric acid, is used more widely in industrial organic chemistry, e.g. for vinyl chloride and dichloroethane.

Pickling of steel
One of the most important applications of hydrochloric acid is in the pickling of steel, to remove rust or iron oxide scale from iron or steel before subsequent processing, such as extrusion, rolling, galvanizing, and other techniques.
Technical quality HCl at typically 18% concentration is the most commonly used pickling agent for the pickling of carbon steel grades.

The spent acid has long been reused as iron(II) chloride (also known as ferrous chloride) solutions, but high heavy-metal levels in the pickling liquor have decreased this practice.

The steel pickling industry has developed hydrochloric acid regeneration processes, such as the spray roaster or the fluidized bed HCl regeneration process, which allow the recovery of HCl from spent pickling liquor.
The most common regeneration process is the pyrohydrolysis process.

In industry demanding purity (food, pharmaceutical, drinking water), high-quality hydrochloric acid is used to control the pH of process water streams.
In less-demanding industry, technical quality hydrochloric acid suffices for neutralizing waste streams and swimming pool pH control.

Regeneration of ion exchangers
High-quality hydrochloric acid is used in the regeneration of ion exchange resins.
Cation exchange is widely used to remove ions such as Na+ and Ca2+ from aqueous solutions, producing demineralized water.
The acid is used to rinse the cations from the resins.
Na+ is replaced with H+ and Ca2+ with 2 H+.

Ion exchangers and demineralized water are used in all chemical industries, drinking water production, and many food industries.

Laboratory use
Of the common strong mineral acids in chemistry, hydrochloric acid is the monoprotic acid least likely to undergo an interfering oxidation-reduction reaction.
Hydrochloric acid is one of the least hazardous strong acids to handle; despite its acidity, it contains the non-reactive and non-toxic chloride ion.

Intermediate-strength hydrochloric acid solutions are quite stable upon storage, maintaining their concentrations over time.
These attributes, plus the fact that it is available as a pure reagent, make hydrochloric acid an excellent acidifying reagent.
Hydrochloric acid is also inexpensive.

Hydrochloric acid is the preferred acid in titration for determining the amount of bases.
Strong acid titrants give more precise results due to a more distinct endpoint.
Azeotropic, or "constant-boiling", hydrochloric acid (roughly 20.2%) can be used as a primary standard in quantitative analysis, although its exact concentration depends on the atmospheric pressure when it is prepared.

Other
Hydrochloric acid is used for a large number of small-scale applications, such as leather processing, household cleaning, and building construction.
Oil production may be stimulated by injecting hydrochloric acid into the rock formation of an oil well, dissolving a portion of the rock, and creating a large-pore structure.
Oil well acidizing is a common process in the North Sea oil production industry.

Hydrochloric acid has been used for dissolving calcium carbonate, e.g. such things as de-scaling kettles and for cleaning mortar off brickwork. When used on brickwork the reaction with the mortar only continues until the acid has all been converted, producing calcium chloride, carbon dioxide, and water:

Many chemical reactions involving hydrochloric acid are applied in the production of food, food ingredients, and food additives.
Typical products include aspartame, fructose, citric acid, lysine, hydrolyzed vegetable protein as food enhancer, and in gelatin production.
Food-grade (extra-pure) hydrochloric acid can be applied when needed for the final product.

Presence in living organisms
Gastric acid is one of the main secretions of the stomach.
Hydrochloric acid consists mainly of hydrochloric acid and acidifies the stomach content to a pH of 1 to 2.
Chloride (Cl−) and hydrogen (H+) ions are secreted separately in the stomach fundus region at the top of the stomach by parietal cells of the gastric mucosa into a secretory network called canaliculi before it enters the stomach lumen.

Gastric acid acts as a barrier against microorganisms to prevent infections and is important for the digestion of food.
Hydrochloric acid's low pH denatures proteins and thereby makes them susceptible to degradation by digestive enzymes such as pepsin.
The low pH also activates the enzyme precursor pepsinogen into the active enzyme pepsin by self-cleavage.
After leaving the stomach, the hydrochloric acid of the chyme is neutralized in the duodenum by bicarbonate.

The stomach itself is protected from the strong acid by the secretion of a thick mucus layer, and by secretin induced buffering with sodium bicarbonate. Heartburn or peptic ulcers can develop when these mechanisms fail. Drugs of the antihistaminic and proton pump inhibitor classes can inhibit the production of acid in the stomach, and antacids are used to neutralize excessive existing acid.

Safety
A rhombic-shaped label with letters 8 and "corrosive", indicating that drops of a liquid corrode materials and human hands.
Causes severe skin burns and eye damage.
May cause respiratory irritation.

Being a strong acid, hydrochloric acid is corrosive to living tissue and to many materials, but not to rubber.
Typically, rubber protective gloves and related protective gear are used when handling concentrated solutions.

Vapors or mists are a respiratory hazard, which can be partially mitigated by use of a respirator equipped with cartridges specifically designed to capture hydrochloric acid.
Airborne acid is an irritant to the eyes, and may require the use of protective goggles or a facemask.

Molar mass: 36.46 g
Density: 0.81 g/cm3
XLogP3-AA: 0.8
Hydrogen Bond Donor Count: 1

Hydrogen Bond Acceptor Count: 0
Rotatable Bond Count: 0
Exact Mass: 35.9766777 g/mol
Monoisotopic Mass: 35.9766777 g/mol

Topological Polar Surface Area: 0Å²
Heavy Atom Count: 1
Formal Charge: 0
Complexity: 0

Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0

Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 1
Compound Is Canonicalized: Yes

At room temperature, hydrogen chloride is a colorless to slightly yellow, corrosive, nonflammable gas that is heavier than air and has a strong irritating odor.
On exposure to air, hydrogen chloride forms dense white corrosive vapors.

Hydrogen chloride can be released from volcanoes.
Hydrogen chloride has many uses, including cleaning, pickling, electroplating metals, tanning leather, and refining and producing a wide variety of products.

Hydrogen chloride can be formed during the burning of many plastics.
Upon contact with water, it forms hydrochloric acid.
Both hydrogen chloride and hydrochloric acid are corrosive.

Hydrochloric acid, solution is a colorless watery liquid with a sharp, irritating odor.
Consists of hydrogen chloride, a gas, dissolved in water.
Sinks and mixes with water.
Produces irritating vapor.

Hydrogen chloride, anhydrous appears as a colorless gas with a sharp, pungent odor.
Fumes strongly in moist air.
Nonflammable.
Corrosive to metals and tissues and irritating to the eyes and respiratory system. Heavier than air.

Long-term inhalation of low concentrations or short-term inhalation of high concentrations has adverse health effects.
Prolonged exposure to fire or intense heat may result in the violent rupture and rocketing of the container.
Used in the manufacture of rubber, pharmaceuticals, chemicals, and in gasoline refining and metals processing.

Hydrogen chloride, refrigerated liquid appears as a colorless liquid with a sharp, pungent odor. Vapors are heavier than air.
Long-term inhalation of low concentrations of vapors or short-term inhalation of high concentrations has adverse health effects.
Exposure of the container to intense heat may cause its violent rupture and rocketing.

Chlorine atom is a halogen.
Hydrochloric acid has a role as a micronutrient.
Hydrochloric acid has many uses.
Hydrochloric acid is used in the production of chlorides, fertilizers, and dyes, in electroplating, and in the photographic, textile, and rubber industries.

Hydrochloric acid is corrosive to the eyes, skin, and mucous membranes.
Acute (short-term) inhalation exposure may cause eye, nose, and respiratory tract irritation and inflammation and pulmonary edema in humans.
Acute oral exposure may cause corrosion of the mucous membranes, esophagus, and stomach and dermal contact may produce severe burns, ulceration, and scarring in humans.

Chronic (long-term) occupational exposure to hydrochloric acid has been reported to cause gastritis, chronic bronchitis, dermatitis, and photosensitization in workers.
Prolonged exposure to low concentrations may also cause dental discoloration and erosion.
EPA has not classified hydrochloric acid for carcinogenicity.

HCl refers to both hydrogen chloride gas and aqueous hydrochloric acid.
Hydrogen chloride gas is a colorless gas formed from the reaction of hydrogen with chlorine.
Hydrochloric acid forms white fumes of hydrochloric acid upon contact with atmospheric humidity.

Hydrochloric acid is a highly corrosive, strong mineral acid with many industrial uses. Hydrochloric acid is found naturally in gastric acid. Hydrogen chloride gas and hydrochloric acid are important in technology and industry.

For example, hydrochloric acid is used in the chemical industry as a chemical reagent in the large-scale production of vinyl chloride for PVC plastic, and MDI/TDI for polyurethane.
Hydrochloric acid has numerous smaller-scale applications, including household cleaning, production of gelatin and other food additives, descaling, and leather processing.

Hydrogen chloride is less widely used, although even in the absence of water, hydrogen chloride can still act as an acid.
For example, hydrogen chloride can dissolve in certain other solvents such as methanol, protonate molecules or ions, and serve as an acid-catalyst for chemical reactions where anhydrous (water-free) conditions are desired.

Hydrogen chloride is corrosive, particularly in the presence of moisture.
Likewise hydrochloric acid is also extremely corrosive.
Most hydrochloric acid is sold or is available as a 38% aqueous solution.

A strong corrosive acid that is commonly used as a laboratory reagent.
Hydrochloric acid is formed by dissolving hydrogen chloride in water.
Gastric acid is the hydrochloric acid component of Gastric juice.

Hydrochloric acid is the aqueous solution of hydrogen chloride gas and the main component of gastric acid, an acid produced naturally in the human stomach to help digest food.
Hydrochloric acid is synthetically produced for a variety of industrial and commercial applications.

Hydrochloric acid can be used to process steel for the building and construction industry.
Hydrochloric acid is used in the chemical industry in the large-scale production of vinyl chloride used to make PVC, and it is one of the chemicals used to produce polyurethane foam and calcium chloride.

Common end uses for hydrochloric acid include household cleaners, pool maintenance and food manufacturing.

OSHA recommends workers in industrial settings wear personal protective equipment such as vapor respirators, rubber gloves, splash goggles and face shields when handling hydrochloric acid.

Plastic containers, such as those made of PVC, can typically be used to store hydrochloric acid. Metal containers are generally not suitable for storing hydrochloric acid due to its corrosive nature.

Hydrochloric acid is a strong, corrosive acid that can be used industrially to process steel used in the building and construction industry.
Hydrochloric acid is used in the chemical industry in the large-scale production of vinyl chloride used to make polyvinyl chloride (PVC) plastic, and it is one of the chemicals that is used to produce polyurethane foam and calcium chloride.

Hydrochloric acid is also used to make many other chemicals and as a disinfectant and slimicide, a chemical that prevents the growth of slime in paper stock.

Other common end uses for hydrochloric acid include household cleaners, pool maintenance and food manufacturing.

Hydrochloric acid is commonly used for the neutralization of alkaline agents, as a bleaching agent, in food, textile, metal, and rubber industries.
Hydrochloric acid is neutralized if released into the soil and it rapidly hydrolyzes when exposed to water.
Transport through soil may contaminate groundwater and will dissolve some of the soil materials.

Exposure to HCl gas or solutions of HCl may cause eye irritation and permanent damage with loss of sight.
Dermal exposure may cause burns.
Inhalation of HCl immediately causes severe irritation with cough and choking sensation.
HCl is not classifiable as to its carcinogenicity to humans.

Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride.
Hydrochloric acid is a colorless solution with a distinctive pungent smell.

Hydrochloric acid is classified as a strong acid.
Hydrochloric acid is a component of the gastric acid in the digestive systems of most animal species, including humans.

Hydrochloric acid is an important laboratory reagent and industrial chemical.
Hydrochloric acid is the salt of the protonated water and chloride.

Hydrochloric acids ions are often written as H3O+ Cl−, although the cation is in fact often bonded to other water molecules.
A combined IR, Raman, X-ray, and neutron diffraction study of concentrated hydrochloric acid revealed that the primary form of H+(aq) in these solutions is H5O2+, which, along with the chloride anion, is hydrogen-bonded to neighboring water molecules in several ways.

As a strong acid, hydrogen chloride has a large Ka.
Theoretical estimates suggest that the pKa of hydrogen chloride is −5.9.

However, Hydrochloric acid is important to distinguish between hydrogen chloride gas and hydrochloric acid.
Due to the leveling effect, except when highly concentrated and behavior deviates from ideality, hydrochloric acid (aqueous HCl) is only as acidic as the strongest proton donor available in water, the aquated proton.

Hydrochloric acid is usually prepared industrially by dissolving hydrogen chloride in water.
Hydrochloric acid can be generated in many ways, and thus several precursors to hydrochloric acid exist.

The large-scale production of hydrochloric acid is almost always integrated with the industrial scale production of other chemicals, such as in the chloralkali process which produces hydroxide, hydrogen, and chlorine, the latter of which can be combined to produce HCl.
Hydrochloric acid is produced in solutions up to 38% HCl (concentrated grade).

Higher concentrations up to just over 40% are chemically possible, but the evaporation rate is then so high that storage and handling require extra precautions, such as pressurization and cooling.
Bulk industrial-grade is therefore 30% to 35%, optimized to balance transport efficiency and product loss through evaporation.

In the United States, solutions of between 20% and 32% are sold as muriatic acid.
Solutions for household purposes in the US, mostly cleaning, are typically 10% to 12%, with strong recommendations to dilute before use.

In the United Kingdom, where Hydrochloric acid is sold as "Spirits of Salt" for domestic cleaning, the potency is the same as the US industrial grade.
In other countries, such as Italy, hydrochloric acid for domestic or industrial cleaning is sold as, and its concentration ranges from 5% to 32%.

Hydrochloric acid is a strong inorganic acid that is used in many industrial processes such as refining metal.
The application often determines the required product quality.

Hydrochloric acid is used more widely in industrial organic chemistry, e.g. for vinyl chloride and dichloroethane.
The steel pickling industry has developed hydrochloric acid regeneration processes, such as the spray roaster or the fluidized bed Hydrochloric acid regeneration process, which allow the recovery of HCl from spent pickling liquor.

Of the six common strong mineral acids in chemistry, hydrochloric acid is the monoprotic acid least likely to undergo an interfering oxidation-reduction reaction.
Hydrochloric acid is one of the least hazardous strong acids to handle; despite its acidity, it contains the non-reactive and non-toxic chloride ion.

Hydrochloric acid is also inexpensive.
Hydrochloric acid is the preferred acid in titration for determining the amount of bases.

Strong acid titrants give more precise results due to a more distinct endpoint.
Hydrochloric acid can be used as a primary standard in quantitative analysis, although its exact concentration depends on the atmospheric pressure when it is prepared.

Hydrochloric acid is used for a large number of small-scale applications, such as leather processing, household cleaning, and building construction.
Oil production may be stimulated by injecting hydrochloric acid into the rock formation of an oil well, dissolving a portion of the rock, and creating a large-pore structure.

Hydrochloric acid has been used for dissolving calcium carbonate, e.g. such things as de-scaling kettles and for cleaning mortar off brickwork.
Many chemical reactions involving hydrochloric acid are applied in the production of food, food ingredients, and food additives.

Typical products include aspartame, fructose, citric acid, lysine, hydrolyzed vegetable protein as food enhancer, and in gelatin production.
Food-grade (extra-pure) hydrochloric acid can be applied when needed for the final product.

The name given to the aqueous solution of hydrogen chloride, which is gaseous at room temperature and normal pressure, consisting of the elements hydrochloric acid, hydrogen and chlorine.
Hydrochloric acid is also known as the spirit of salt among the people.

During the Industrial Revolution, acid, whose importance was discovered in the industry, started to be produced in the industry first by the Leblanc process and then by the Solvay process.
Hydrochloric acid has played an important role in the discovery of new conveniences in history.

Today, hydrochloric acid is used in almost all fields, from PVC to iron and steel, from organic matter production to the food industry.
In addition to the conveniences Hydrochloric acid provides, hydrochloric acid is a toxic substance and causes great damage to most surfaces, especially human tissues.

Therefore, safety precautions should be kept at the highest level while working with this acid.
In addition to being toxic, acid is irritating to the eyes and skin, causes burns on the skin, and is irritating to the respiratory system.

In order to obtain hydrochloric acid, hydrogen chloride gas must first be obtained.
Hydrogen chloride is a strong acid.

Hydrogen chloride, whose molecular structure is quite simple, consists of a chlorine atom and a hydrogen atom, and its formula is HCl.
Hydrogen chloride dissolves very highly in one liter of water at room temperature, about 450 liters.

Like other acids, Hydrochloric acid imparts a color called "acid color" by the colored reagent; for example, Hydrochloric acid dyes litmus red, heliantine pink, bromophenol yellow, and gives a colorless liquid with phenolphthalein.
Hydrochloric acid has a pronounced effect on bases such as sodium carbonate and ammonia.

When a sodium carbonate solution is gradually poured into a glass tube containing a certain volume of hydrochloric acid, a thermometer inserted into the tube will show that the temperature has risen rapidly; If the solution is heated until the water is completely gone, sodium chloride (table salt) precipitates in solid form.
If a bottle containing hydrochloric acid is brought close to the mouth of a bottle containing ammonia, white and copious amounts of ammonium chloride fumes are produced.

With this reaction, Hydrochloric acid is determined whether the substances in question are present in an environment.
When hydrochloric acid is dropped into water, Hydrochloric acid gives H+ ions.

As a typical acid feature, hydrochloric acid acts on many metals such as zinc, iron, magnesium or aluminum and releases hydrogen.
Copper reacts with this acid only in the presence of oxygen from the air; but hydrogen is not released.

Although gold and platinum do not react with hydrochloric acid, they dissolve in a mixture of aqua regia, which affects almost all metals.
Hydrochloric acids usually undergo dissolution in hydrochloric acid.

The rust removing role of hydrochloric acid is based on this phenomenon.
Hydrochloric acids react violently with hydrochloric acid and carbon dioxide is released.

Other salts react with hydrochloric acid; for example, silver nitrate reacts with hydrochloric acid to give a white precipitate of silver chloride; the precipitate turns bruised when exposed to light.
In addition to being used as a rust remover, hydrochloric acid is used to produce chlorinated products by affecting organic compounds.

Hydrochloric acid is a type of inorganic acid that has uses in a variety of different business areas.
The concentration of the acid varies according to the work area where it is used.

Hydrochloric acid is used in many industrial sub-branches for pickling steel, forming organic compounds, producing inorganic substances in industrial branches and providing pH balance.
Hydrochloric acid is one of the intermediates in chemistry.

This acid is used in many small-scale industries.
Leather processing, house cleaning, construction industry are among them.

In oil exploration, information about the presence and/or quality of oil can be gathered by injecting hydrochloric acid into the rocks.
Acid is also used in the production of additives in the food industry.

Hydrochloric acid makes use of hydrochloric acid especially in artificial foods and vitamins during the production phase.
Hydrochloric acid, solution is a colorless watery liquid with a sharp, irritating odor.

Consists of hydrogen chloride, a gas, dissolved in water.
Sinks and mixes with water.

Produces irritating vapor.
At room temperature, Hydrochloric acid is a colorless to slightly yellow, corrosive, nonflammable gas that is heavier than air and has a strong irritating odor.

On exposure to air, Hydrochloric acid forms dense white corrosive vapors.
Hydrochloric acid can be released from volcanoes.

Hydrochloric acid has many uses, including cleaning, pickling, electroplating metals, tanning leather, and refining and producing a wide variety of products.
Hydrochloric acid can be formed during the burning of many plastics.

Upon contact with water, it forms hydrochloric acid.
Hydrochloric acids are corrosive.

Hydrochloric acid has many uses.
Hydrochloric acid is corrosive to the eyes, skin, and mucous membranes.

Hydrochloric acid is commonly used for the neutralization of alkaline agents, as a bleaching agent, in food, textile, metal, and rubber industries.
Hydrochloric acid is neutralized if released into the soil and Hydrochloric acid rapidly hydrolyzes when exposed to water.

Transport through soil may contaminate groundwater and will dissolve some of the soil materials.
Exposure to Hydrochloric acid gas or solutions of Hydrochloric acid may cause eye irritation and permanent damage with loss of sight.

Dermal exposure may cause burns.
Inhalation of Hydrochloric acid immediately causes severe irritation with cough and choking sensation.

Hydrochloric acid causes local pH changes and denatures proteins.
Hydrochloric acid leads to edema formation and tissue necrosis.

Hydrochloric acid produces a coagulation necrosis characterized by the formation of an eschar.
Ingested Hydrochloric acid may give rise to damage of the esophagus and stomach.

Hydrochloric acid is a colorless corrosive, strong mineral acid with many industrial uses among which, when Hydrochloric acid reacts with an organic base it forms a hydrochloride salt.
Hydrochloric acid is a weak reducing acid and is not generally used to digest organic materials.

Hydrochloric acid is an excellent solvent for carbonates, phosphates, many metal oxides, and metals.
For example, due to Hydrochloric acids reducing properties and the complexing ability of Cl−, HCl is a better solvent for dissolving iron and manganese oxides than HNO3.

For silicate analysis, Hydrochloric acid is generally used in combination with other acids, such as HF and HNO3, although some basic silicate minerals can be completely or partially decomposed by HCl alone.
At elevated temperatures and pressures, many silicates and other refractory oxides, sulfates, and fluorides are attacked by HCl to produce soluble salts.

Hydrochloric acid is a versatile chemical that hydrochloric acid is used in the chemical industry as a chemical reagent in the large-scale production of vinyl chloride (CH2double bondCHCl) for PVC plastic, and polyurethane.
Hydrochloric acid may be manufactured by several different processes; however, most of the hydrochloric acid (hydrogen chloride) produced in the United States is a by-product of the chlorination reaction.

After leaving the chlorination process, the gas stream containing hydrogen chloride proceeds to the absorption column, where concentrated liquid hydrochloric acid is produced by absorption of hydrogen chloride vapors into a weak solution of hydrochloric acid.
Hydrochloric acid-free chlorination gases are removed for further processing.

Hydrochloric acid is then either sold or used elsewhere in the plant.
The final gas stream is sent to a scrubber to remove the remaining hydrogen chloride prior to venting.

Hydrochloric acid is supplied commercially at concentrations mainly within the range 28–36% w/w.
At these concentrations it evolves hydrogen chloride vapour with a sharp irritant odour.

Both the acid and the vapour are highly corrosive to most common metals.
Suitable materials for storage tanks are indicated.

To avoid corrosion to adjacent plant and equipment from any escaping vapour, storage and dosing plant should preferably be located in dedicated rooms.
Vent lines from storage tanks should feed into a scrubber unit, designed to cope with the fumes given off and the pressures generated during the filling of the tank.

Water, sodium hydroxide solution or dilute acid solution can be used as the scrubbing medium.
Hydrochloric acid is used then released via effluent flows by the paper industry.

Hydrochloric acid is a solution of hydrogen chloride (HCl) dissolved in water.
Hydrochloric acid is a highly corrosive, strong acid, and can be a clear/colorless or light yellow liquid.

Hydrochloric acid is used in the chemical industry mainly as a chemical reagent in the large-scale production of vinyl chloride for polyvinyl chloride plastic and methylene diphenyl diisocyanate/TDI for polyurethane.
Also, since Hydrochloric acid ionizes completely into H3O+ and Cl−, it can easily be used to produce salts like sodium chloride (NaCl).

Hydrochloric acid is usually produced with a concentration between 0% and 38% kg HCl/kg.
If the concentration of HCl is very low, approaching 0% HCl, the solution behaves similarly to liquid water.

If the concentration is high, above 30%, the boiling point decreases rapidly and evaporation rate increases.
Forty percent Hydrochloric acid is known as “fuming” hydrochloric acid because of its extremely high evaporation rate.

Hydrochloric acid is the water-based, or aqueous, solution of hydrogen chloride gas.
Hydrochloric acid is also the main component of gastric acid, an acid produced naturally in the human stomach to help digest food.

Hydrochloric acid is also synthetically produced for a variety of industrial and commercial applications, and can be formed by a number of manufacturing processes, including dissolving hydrogen chloride gas in water.
Hydrochloric acid is a strong, corrosive acid that can be used industrially to process steel used in the building and construction industry.

Hydrochloric acid is used in the chemical industry in the large-scale production of vinyl chloride used to make polyvinyl chloride (PVC) plastic, and it is one of the chemicals that is used to produce polyurethane foam and calcium chloride.
Hydrochloric acid is also used to make many other chemicals and as a disinfectant and slimicide, a chemical that prevents the growth of slime in paper stock.

Other common end uses for hydrochloric acid include household cleaners, pool maintenance and food manufacturing.
Hydrochloric acid is used in the production of chlorides, for refining ore in the production of tin and tantalum, for pickling and cleaning of metal products, in electroplating, in removing scale from boilers, for the neutralization of basic systems, as a laboratory reagent, as a catalyst and solvent in organic syntheses, in the manufacture of fertilizers and dyes, for hydrolyzing starch and proteins in the preparation of various food products, and in the photographic, textile, and rubber industries.

Hydrochloric acid, corrosive colourless acid that is prepared by dissolving gaseous hydrogen chloride in water.
Hydrochloric acid (HCl) is a corrosive, toxic, inorganic, strongly acidic, aqueous solution of completely ionized hydrogen chloride.

Hydrochloric acid is used in organic and inorganic compound production, as a reagent in reactions and sample preparation, in pH control, etc.
Hydrochloric acid is used in the manufacture of phosphoric acid, chlorine dioxide, ammonium chloride, fertilisers, dyes, and artificial silk and pigments for paints.

Hydrochloric acid is used as a refining ore in the production of tin and tantalum, as a lab reagent, and as a metal treating agent.
Hydrochloric acid is used to remove scale and dust from boilers and heat exchange equipment, to clean membranes in desalination plants, to increase oil well output, to prepare synthetic rubber products by treating isoprene, and to clean and prepare other metals for coatings.

Hydrochloric acid is used in the neutralisation of waste streams, the recovery of zinc from galvanised iron scrap, the production of chloride chemicals, the production of vinyl chloride from acetylene and alkyl chlorides from olefins, the manufacture of sodium glutamate and gelatine, the conversion of cornstarch to syrup, sugar refining, electroplating, soap refining, leather tanning, and the photographic, textile, brewing, and rubber industries.
Hydrochloric acid is used to maintain pH balance in swimming pools, spas, etc.

Hydrochloric acid is also used as a bactericide, a fungicide, and a virucide to disinfect bathrooms, kitchens and food preparation areas, and other areas in commercial and industrial buildings, in hospitals, in nursing homes, and in and around household dwellings.
Hydrochloric acid is used in food processing as a starch modifier.

Hydrochloric acid is a solution of hydrogen chloride in water.
Hydrochloric acid occurs as either a colourless liquid with a an irritating, pungent odour, or a colourless to slightly yellow gas which can be shipped as a liquefied compressed gas; highly soluble in water.

Hydrochloric acid is one of the most important industrial chemicals and has numerous applications.
Both anhydrous hydrogen chloride and aqueous acid are used to produce a large number of chloride salts.

The acid also is a common laboratory reagent.
Some major applications of hydrochloric acid include processing of ores and extraction of metals from their minerals; in metal cleaning, particularly in steel pickling to dissolve oxide impurities; production of alumina, titanium dioxide, and other metal oxides by various hydrometallurgical processes; production of hydrogen; synthesis of chlorine dioxide; removal of heavy metal impurities from carbon black; activation of bentonite clays; etching of concrete surfaces for finishing operations; and as a catalyst in several organic reactions such as inversion of sugar, hydrolysis of starch to obtain sugar syrup, and esterification of aromatic acids.

Hydrochloric acid gas is used to produce phosphonium chloride, PH4Cl, which is a flame retardant for cotton textiles.
Other major applications include manufacture of a number of high purity metal chlorides, ammonium chloride, chlorosulfuric acid; recovery of waste metals; preparation of alkyl chlorides and chloroacetic acids; and as a chlorinating agent in organic syntheses.

Rubber Hydrochloric acid, which results from the treatment of natural rubber with hydrogen chloride, can be cast in film from solutions.
Such rubber hydrochloride films provide a strong, water resistant packaging material for meats and other foods, paper products, and textiles.

A water solution of hydrogen chloride of varied concentrations.
Hydrochloric acid is a clear, colorless or slightly yellowish, corrosive liquid having a pungent odor.

Hydrochloric acid is miscible with water and with alcohol.
Concentrations of hydrochloric acid are expressed in percent by weight, or may be expressed in Baume degrees (Be0) from which percentages of hydrochloric acid and specific gravities may readily be derived.

The usually available concentrations are 18°, 20°, 22°, and 23° Be. Concentrations above 13° Be (19.6%) fume in moist air, lose hydrogen chloride, and create a corrosive atmosphere.
Because of these characteristics, suitable precautions must be observed during sampling and analysis to prevent losses.

Hydrochloric acid is produced by various methods that might impart trace amounts of organic compounds as impurities.
The manufacturer, vendor, or user is responsible for identifying the specific organic compounds that are present and for meeting the requirements for organic compounds.

Methods are provided for their determination.
In applying the procedures any necessary standards should be used to quantitate the organic compounds present in each specific product.

Hydrochloric acid, or hydrogen chloride, is either a colorless liquid with a pungent odor, or a colorless to slightly yellow gas that can be shipped as a liquefi ed compressed gas. The acid is used in the production of fertilizers, dyes, dyestuffs, artifi cial silk, and paint pig- ments, and in refi ning edible oils and fats. Hydrochloric acid is also used in electroplating, leather tanning, ore refi ning, soap refi ning, petroleum extraction, and pickling of metals, and is used in the photographic, textile, and rubber industries. In addition, hydrochloric acid is used as an antiseptic in toilet bowls, and in food processing as a starch modifier.
Hydrochloric acid is also used extensively in pharmaceuticals and the food industry.

When Hydrochloric acid is listed after a drug name, the drug was produced by combining a free base and hydrochloric acid to produce a hydrochloride salt.
Drugs delivered as hydrochloride salts rather than free bases are more soluble in water than free forms of the drugs, tend to be more stable, are solids, and are often more compatible with the chemistry of the digestive system. In the food industry it is used in the production of gelatin and sodium glutamate, to convert cornstarch to syrup, to refine sugar, and as an acidulant.

Hydrochloric acid is one of the most widely used acids and a common laboratory reagent.
Hydrochloric acid is used in the manufacture of chlorides, in the pickling and cleaning of metal products, as a processing agent for manufacturing various food products, as a cleaning agent, in organic synthesis, and for neutralizing alkalies.

In the production of chlorides; refining ore in the production of tin and tantalum; for the neutralization of basic systems; as laboratory reagent; hydrolyzing of starch and proteins in the preparation of various food products; pickling and cleaning of metal products; as catalyst and solvent in organic syntheses.
Also used for oil- and gas-well treament and in removing scale from boilers and heat-exchange equipment.

Hydrochloric acid is a highly corrosive liquid, emitting a pungent odor and fumes in moist air.
Concentrated hydrochloric acid is one of the strongest acids and thus any desired pH from 0 to 7 can be easily achieved with the required dosage.

Hydrochloric acid is seldom used in mineral flotation.
The largest use is in hydrometallurgical processes and the pickling of hot rolled steel.
In some cases, hydrochloric acid is used for decoating iron-stained mineral surfaces before flotation.

Uses
Hydrochloric acid is used in pickling operations to remove rust and other impurities from carbon, alloy and stainless steel, to prepare the steel for final applications in building and construction projects, and in products such as car bodies and household appliances.
Hydrochloric acid is also used in aluminum etching and metal cleaning applications.

Hydrochloric acid can be an ingredient in household cleaners such as toilet bowl cleaners, bathroom tile cleaners and other porcelain cleaners, due to its corrosive properties that help clean tough stains.
Hydrochloric acid is used as a swimming pool treatment chemical, to help maintain an optimal pH in the water.

The food industry uses hydrochloric acid to process a variety of food products, such as corn syrups used in soft drinks, cookies, crackers, ketchup and cereals.
Hydrochloric acid is also used as an acidifier in sauces, vegetable juices and canned goods, to help enhance flavor and reduce spoilage.

When hydrochloric acid is mixed or reacted with limestone, it produces calcium chloride, a type of salt used to de-ice roads.
Hydrochloric acid also has uses in food production as a stabilizer and firming agent, for example in baked goods, as well as uses as an antimicrobial.

Hydrochloric acid is used in the production of batteries, photoflash bulbs and fireworks.
Hydrochloric acid is also used in leather processing, building and construction, oil well acidizing and producing gelatin products.