- 1 History
- 2 Chemistry
- 3 Physical properties
- 4 Production
- 5 Applications
- 6 Presence in living organisms
- 7 Safety
- 8 See also
- 9 References
- 10 External links
중세 시대에 염산을 얻었던 방법에 대한 언급은 없었다. 하지만, 이것은 그것을 15세기 와 16세기의 작품에서 찾을수 있을 것 같다. 그러나 아직도 그것은 논쟁의 문제이다. Some authors maintain that it was first discovered by the German benedictine monk Basil Valentine in the 15th century, by heating common salt and green vitriol, while others claim that it was first described in the "Plichto", a book about dyes written by the venetian Gioanventura Rossetti in the late 16th century.
In the seventeenth century, Johann Rudolf Glauber from Karlstadt am Main, Germany, used sodium chloride salt and sulfuric acid for the preparation of sodium sulfate in the Mannheim process, releasing hydrogen chloride gas. Joseph Priestley of Leeds, England prepared pure hydrogen chloride in 1772, and in 1818 Humphry Davy of Penzance, England, proved that the chemical composition included hydrogen and chlorine.
During the Industrial Revolution in Europe, demand for alkaline substances increased. A new industrial process by Nicolas Leblanc (Issoundun, 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 vented to air. 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 twentieth 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 the year 2000, hydrochloric acid is mostly made by absorbing by-product hydrogen chloride from industrial organic compounds production.
Since 1988, hydrochloric acid has been listed as a Table II precursor under the 1988 United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances because of its use in the production of heroin, cocaine, and methamphetamine.
Hydrogen chloride (HCl) is a monoprotic acid, which means it can dissociate (i.e., ionize) only once to give up one H+ ion (a single proton). In aqueous hydrochloric acid, the H+ joins a water molecule to form a hydronium ion, H3O+:
- HCl + H2O → H3O+ + Cl−
The other ion formed is Cl−, the chloride ion. Hydrochloric acid can therefore be used to prepare salts called chlorides, such as sodium chloride. Hydrochloric acid is a strong acid, since it is essentially completely dissociated in water.
Monoprotic acids have one acid dissociation constant, Ka, which indicates the level of dissociation in water. For a strong acid like HCl, the Ka is large. Theoretical attempts to assign a Ka to HCl have been made. When chloride salts such as NaCl are added to aqueous HCl they have practically no effect on pH, indicating that Cl− is an exceedingly weak conjugate base and that HCl is fully dissociated in aqueous solution. For intermediate to strong solutions of hydrochloric acid, the assumption that H+ molarity (a unit of concentration) equals HCl molarity is excellent, agreeing to four significant digits.
Of the six common strong mineral acids in chemistry, hydrochloric acid is the monoprotic acid least likely to undergo an interfering oxidation-reduction reaction. It is one of the least hazardous strong acids to handle; despite its acidity, it consists of 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, mean that hydrochloric acid makes an excellent acidifying reagent.
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.
Hydrochloric acid is frequently used in chemical analysis to prepare ("digest") samples for analysis. Concentrated hydrochloric acid dissolves many metals and forms oxidized metal chlorides and hydrogen gas, and it reacts with basic compounds such as calcium carbonate or copper(II) oxide, forming the dissolved chlorides that can be analyzed.
|kg HCl/kg||kg HCl/m3||Baumé||kg/l||mol/dm3||mPa·s||kJ/(kg·K)||Pa||°C||°C|
The physical properties of hydrochloric acid, such as boiling and melting points, density, and pH depend on the concentration or molarity of HCl in the acid 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 (227 °F). There are four constant-crystallization eutectic points for hydrochloric acid, between the crystal form of HCl·H2O (68% HCl), HCl·2H2O (51% HCl), HCl·3H2O (41% HCl), HCl·6H2O (25% HCl), and ice (0% HCl). There is also a metastable eutectic point at 24.8% between ice and the HCl·3H2O crystallization.
Hydrochloric acid is prepared 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.
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 need extra precautions, such as pressure and low temperature. Bulk industrial-grade is therefore 30% to 34%, optimized for effective transport and limited product loss by HCl vapors. 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.
Major producers worldwide include Dow Chemical at 2 million metric tons annually (2 Mt/year), calculated as HCl gas, and FMC, 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.
Hydrochloric acid is a strong inorganic acid that is used in many industrial processes. The application often determines the required product quality.
Pickling of steel[편집]
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.
- Fe2O3 + Fe + 6 HCl → 3 FeCl2 + 3 H2O
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, applying the following formula:
- 4 FeCl2 + 4 H2O + O2 → 8 HCl+ 2 Fe2O3
Production of organic compounds[편집]
Another major use of hydrochloric acid is in the production of organic compounds, such as vinyl chloride and dichloroethane for PVC. This is often captive use, consuming locally produced hydrochloric acid that never actually reaches the open market. Other organic compounds produced with hydrochloric acid include bisphenol A for polycarbonate, activated carbon, and ascorbic acid, as well as numerous pharmaceutical products.
- 2 CH2=CH2 + 4 HCl + O2 → 2 ClCH2CH2Cl + 2 H2O (dichloroethane by oxychlorination)
- wood + HCl + heat → activated carbon (chemical activation)
Production of inorganic compounds[편집]
Numerous products can be produced with hydrochloric acid in normal acid-base reactions, resulting in inorganic compounds. These include water treatment chemicals such as iron(III) chloride and polyaluminium chloride (PAC).
- Fe2O3 + 6 HCl → 2 FeCl3 + 3 H2O (iron(III) chloride from magnetite)
Other inorganic compounds produced with hydrochloric acid include road application salt calcium chloride, nickel(II) chloride for electroplating, and zinc chloride for the galvanizing industry and battery production.
- CaCO3 + 2 HCl → CaCl2 + CO2 + H2O (calcium chloride from limestone)
pH Control and neutralization[편집]
- OH− + HCl → H2O + Cl−
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 treatment.
Regeneration of ion exchangers[편집]
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 by H+
- Ca2+ is replaced by 2 H+
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.
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[편집]
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. Its 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 sodium bicarbonate.
The stomach itself is protected from the strong acid by the secretion of a thick, protective 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 existing acid.
|틀:Chembox header|Dangerous goods labels|
Concentrated hydrochloric acid (fuming hydrochloric acid) forms acidic mists. Both the mist and the solution have a corrosive effect on human tissue, with the potential to damage respiratory organs, eyes, skin, and intestines. Upon mixing hydrochloric acid with common oxidizing chemicals, such as sodium hypochlorite (bleach, NaClO) or potassium permanganate (KMnO4), the toxic gas chlorine is produced.
- NaClO + 2 HCl → H2O + NaCl + Cl2
- 2 KMnO4 + 16 HCl → 2 MnCl2 + 8 H2O + 2 KCl + 5 Cl2
|틀:Chembox header colspan="1"|Concentration
|틀:Chembox header colspan="1"|Classification||틀:Chembox header colspan="1"|R-Phrases|
|> 25%||Corrosive (C)||틀:R34 틀:R37|
- Reti, Ladislao. 《How old is Hydrochloric acid?》. Berkeley: University of California Press.
- Waite, A.E (1992). 《Secret Tradition in Alchemy》 public document판. Kessinger Publishing.
- Ernst Sigismund Von Meyer(1891),A History of Chemistry from Earliest Times to the Present Day,p.51
- Andrea Zille(2005), Lacasses reactions for txtile applicationshttp://repositorium.sdum.uminho.pt/bitstream/1822/4899/1/ZillePhD.pdf
- Van Dorst, W.C.A.; et al. (2004). 《Technical product brochure Hydrochloric Acid》 public document판. Amersfoort: Akzo Nobel Base Chemicals.
- 〈Hydrochloric Acid〉. 《Chemicals Economics Handbook》. SRI International. 2001. 733.4000A–733.3003F쪽.
- Aftalion, Fred (1991). 《A History of the International Chemical Industry》. Philadelphia: University of Pennsylvania Press. ISBN 0-8122-1297-5.
- “List of precursors and chemicals frequently used in the illicit manufacture of narcotic drugs and psychotropic substances under international control” (PDF) Eleven판. International Narcotics Control Board. 2007년 1월.
- Lide, David (2000). 《CRC Handbook of Chemistry and Physics》 81판. CRC Press. ISBN 0849304814.
- Perry, R; Green D, Maloney J (1984). 《Perry's Chemical Engineers' Handbook》 6판. McGraw-Hill Book Company. ISBN 0-07-049479-7.
- “Dissociation constants pKa and pKb”. ChemBuddy.com. 2008년 9월 6일에 확인함.
- 〈Systemnummer 6 Chlor〉. 《Gmelins Handbuch der Anorganischen Chemie》. Chemie Berlin. 1927.
- 〈Systemnummer 6 Chlor, Ergänzungsband Teil B - Lieferung 1〉. 《Gmelins Handbuch der Anorganischen Chemie》. Chemie Weinheim. 1968.
- 《Aspen Properties》. binary mixtures modeling software calculations by Akzo Nobel Engineering판. Aspen Technology. 2002–2003.
- Simhon, Rachel (13/09/2003). 《Household plc: really filthy bathroom》. London: Daily Telegraph. 2010년 3월 31일에 확인함.
- Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). 《Human Biology and Health》. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1.
- Arthur, C.; M.D. Guyton, John E. Hall (2000). 《Textbook of Medical Physiology》 10판. W.B. Saunders Company. ISBN 0-7216-8677-X.
- Bowen, R. (2003년 3월 18일). “Control and Physiologic Effects of Secretin”. Colorado State University. 2009년 3월 16일에 확인함.
- “Council Directive 67/548/EEC of 27 June 1967 on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances”. EUR-lex. 2008년 9월 2일에 확인함.
- “HCl score card”. United States Environmental Protection Agency. 2007년 9월 12일에 확인함.
- General safety information
- EPA Hazard Summary
- Hydrochloric acid MSDS by American Bioanalytical
- Hydrochloric acid MSDS by Georgia Institute of Technology
- Pollution information