Metabolism is the set of life-sustaining chemical reactions in organisms. The three main purposes of metabolism are: the conversion of food to energy to run cellular processes; these enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, respond to their environments.. Metabolic reactions may be categorized as catabolic - the breaking down of compounds. Catabolism releases energy, anabolism consumes energy; the chemical reactions of metabolism are organized into metabolic pathways, in which one chemical is transformed through a series of steps into another chemical, each step being facilitated by a specific enzyme. Enzymes are crucial to metabolism because they allow organisms to drive desirable reactions that require energy that will not occur by themselves, by coupling them to spontaneous reactions that release energy. Enzymes act as catalysts - they allow a reaction to proceed more - and they allow the regulation of the rate of a metabolic reaction, for example in response to changes in the cell's environment or to signals from other cells.
The metabolic system of a particular organism determines which substances it will find nutritious and which poisonous. For example, some prokaryotes use hydrogen sulfide as a nutrient, yet this gas is poisonous to animals; the basal metabolic rate of an organism is the measure of the amount of energy consumed by all of these chemical reactions. A striking feature of metabolism is the similarity of the basic metabolic pathways among vastly different species. For example, the set of carboxylic acids that are best known as the intermediates in the citric acid cycle are present in all known organisms, being found in species as diverse as the unicellular bacterium Escherichia coli and huge multicellular organisms like elephants; these similarities in metabolic pathways are due to their early appearance in evolutionary history, their retention because of their efficacy. Most of the structures that make up animals and microbes are made from three basic classes of molecule: amino acids and lipids; as these molecules are vital for life, metabolic reactions either focus on making these molecules during the construction of cells and tissues, or by breaking them down and using them as a source of energy, by their digestion.
These biochemicals can be joined together to make polymers such as DNA and proteins, essential macromolecules of life. Proteins are made of amino acids arranged in a linear chain joined together by peptide bonds. Many proteins are enzymes. Other proteins have structural or mechanical functions, such as those that form the cytoskeleton, a system of scaffolding that maintains the cell shape. Proteins are important in cell signaling, immune responses, cell adhesion, active transport across membranes, the cell cycle. Amino acids contribute to cellular energy metabolism by providing a carbon source for entry into the citric acid cycle when a primary source of energy, such as glucose, is scarce, or when cells undergo metabolic stress. Lipids are the most diverse group of biochemicals, their main structural uses are as part of biological membranes both internal and external, such as the cell membrane, or as a source of energy. Lipids are defined as hydrophobic or amphipathic biological molecules but will dissolve in organic solvents such as benzene or chloroform.
The fats are a large group of compounds that contain fatty glycerol. Several variations on this basic structure exist, including alternate backbones such as sphingosine in the sphingolipids, hydrophilic groups such as phosphate as in phospholipids. Steroids such as cholesterol are another major class of lipids. Carbohydrates are aldehydes or ketones, with many hydroxyl groups attached, that can exist as straight chains or rings. Carbohydrates are the most abundant biological molecules, fill numerous roles, such as the storage and transport of energy and structural components; the basic carbohydrate units are called monosaccharides and include galactose and most glucose. Monosaccharides can be linked together to form polysaccharides in limitless ways; the two nucleic acids, DNA and RNA, are polymers of nucleotides. Each nucleotide is composed of a phosphate attached to a ribose or deoxyribose sugar group, attached to a nitrogenous base. Nucleic acids are critical for the storage and use of genetic information, its interpretation through the processes of transcription and protein biosynthesis.
This information is propagated through DNA replication. Many viruses have an RNA genome, such as HIV, which uses reverse transcription to create a DNA template from its viral RNA genome. RNA in ribozymes such as spliceosomes and ribosomes is similar to enzymes as it can catalyze chemical reactions. Individual nucleosides are made
An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent. Electrically, such a solution is neutral. If an electric potential is applied to such a solution, the cations of the solution are drawn to the electrode that has an abundance of electrons, while the anions are drawn to the electrode that has a deficit of electrons; the movement of anions and cations in opposite directions within the solution amounts to a current. This includes most soluble salts and bases; some gases, such as hydrogen chloride, under conditions of high temperature or low pressure can function as electrolytes. Electrolyte solutions can result from the dissolution of some biological and synthetic polymers, termed "polyelectrolytes", which contain charged functional groups. A substance that dissociates into ions in solution acquires the capacity to conduct electricity.
Sodium, chloride, calcium and phosphate are examples of electrolytes. In medicine, electrolyte replacement is needed when a person has prolonged vomiting or diarrhea, as a response to strenuous athletic activity. Commercial electrolyte solutions are available for sick children and athletes. Electrolyte monitoring is important in the treatment of bulimia; the word electrolyte derives from the Greek lytós, meaning "able to be untied or loosened". Svante Arrhenius put forth, in his 1884 dissertation, his explanation of the fact that solid crystalline salts disassociate into paired charged particles when dissolved, for which he won the 1903 Nobel Prize in Chemistry. Arrhenius's explanation was that in forming a solution, the salt dissociates into charged particles, to which Michael Faraday had given the name "ions" many years earlier. Faraday's belief had been. Arrhenius proposed that in the absence of an electric current, solutions of salts contained ions, he thus proposed. Electrolyte solutions are formed when a salt is placed into a solvent such as water and the individual components dissociate due to the thermodynamic interactions between solvent and solute molecules, in a process called "solvation".
For example, when table salt, NaCl, is placed in water, the salt dissolves into its component ions, according to the dissociation reaction NaCl → Na+ + Cl−It is possible for substances to react with water, producing ions. For example, carbon dioxide gas dissolves in water to produce a solution that contains hydronium and hydrogen carbonate ions. Molten salts can be electrolytes as, for example, when sodium chloride is molten, the liquid conducts electricity. In particular, ionic liquids, which are molten salts with melting points below 100 °C, are a type of conductive non-aqueous electrolytes and thus have found more and more applications in fuel cells and batteries. An electrolyte in a solution may be described as "concentrated" if it has a high concentration of ions, or "diluted" if it has a low concentration. If a high proportion of the solute dissociates to form free ions, the electrolyte is strong; the properties of electrolytes may be exploited using electrolysis to extract constituent elements and compounds contained within the solution.
Alkaline earth metals form hydroxides that are strong electrolytes with limited solubility in water, due to the strong attraction between their constituent ions. This limits their application to situations. In physiology, the primary ions of electrolytes are sodium, calcium, chloride, hydrogen phosphate, hydrogen carbonate; the electric charge symbols of plus and minus indicate that the substance is ionic in nature and has an imbalanced distribution of electrons, the result of chemical dissociation. Sodium is the main electrolyte found in extracellular fluid and potassium is the main intracellular electrolyte. All known higher lifeforms require a subtle and complex electrolyte balance between the intracellular and extracellular environments. In particular, the maintenance of precise osmotic gradients of electrolytes is important; such gradients affect and regulate the hydration of the body as well as blood pH, are critical for nerve and muscle function. Various mechanisms exist in living species that keep the concentrations of different electrolytes under tight control.
Both muscle tissue and neurons are considered electric tissues of the body. Muscles and neurons are activated by electrolyte activity between the extracellular fluid or interstitial fluid, intracellular fluid. Electrolytes may enter or leave the cell membrane through specialized protein structures embedded in the plasma membrane called "ion channels". For example, muscle contraction is dependent upon the presence of calcium and potassium. Without sufficient levels of these key electrolytes, muscle weakness or severe muscle contractions may occur. Electrolyte balance is maintained by oral, or in emergencies, intravenous intake of electrolyte-containing substances, is regulated by hormones, in general with the kidneys flushing out excess levels. In humans, electrolyte homeostasis is regulated by hormones such as antidiuretic hormones and parathyroid hormones. Serious electrol
In chemistry, pH is a scale used to specify how acidic or basic a water-based solution is. Acidic solutions have a lower pH, while basic solutions have a higher pH. At room temperature, pure water is neither acidic nor basic and has a pH of 7; the pH scale is logarithmic and approximates the negative of the base 10 logarithm of the molar concentration of hydrogen ions in a solution. More it is the negative of the base 10 logarithm of the activity of the hydrogen ion. At 25 °C, solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic; the neutral value of the pH depends on the temperature, being lower than 7 if the temperature increases. Contrary to popular belief, the pH value can be less than 0 or greater than 14 for strong acids and bases respectively; the pH scale is traceable to a set of standard solutions whose pH is established by international agreement. Primary pH standard values are determined using a concentration cell with transference, by measuring the potential difference between a hydrogen electrode and a standard electrode such as the silver chloride electrode.
The pH of aqueous solutions can be measured with a glass electrode and a pH meter, or a color-changing indicator. Measurements of pH are important in chemistry, medicine, water treatment, many other applications; the concept of pH was first introduced by the Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory in 1909 and revised to the modern pH in 1924 to accommodate definitions and measurements in terms of electrochemical cells. In the first papers, the notation had the "H" as a subscript to the lowercase "p", as so: pH; the exact meaning of the "p" in "pH" is disputed, but according to the Carlsberg Foundation, pH stands for "power of hydrogen". It has been suggested that the "p" stands for the German Potenz, others refer to French puissance. Another suggestion is that the "p" stands for the Latin terms pondus hydrogenii, potentia hydrogenii, or potential hydrogen, it is suggested that Sørensen used the letters "p" and "q" to label the test solution and the reference solution.
In chemistry, the p stands for "decimal cologarithm of", is used in the term pKa, used for acid dissociation constants. Bacteriologist Alice C. Evans, famed for her work's influence on dairying and food safety, credited William Mansfield Clark and colleagues with developing pH measuring methods in the 1910s, which had a wide influence on laboratory and industrial use thereafter. In her memoir, she does not mention how much, or how little and colleagues knew about Sørensen's work a few years prior, she said: In these studies Dr. Clark's attention was directed to the effect of acid on the growth of bacteria, he found that it is the intensity of the acid in terms of hydrogen-ion concentration that affects their growth. But existing methods of measuring acidity determined not the intensity, of the acid. Next, with his collaborators, Dr. Clark developed accurate methods for measuring hydrogen-ion concentration; these methods replaced the inaccurate titration method of determining acid content in use in biologic laboratories throughout the world.
They were found to be applicable in many industrial and other processes in which they came into wide usage. The first electronic method for measuring pH was invented by Arnold Orville Beckman, a professor at California Institute of Technology in 1934, it was in response to local citrus grower Sunkist that wanted a better method for testing the pH of lemons they were picking from their nearby orchards. PH is defined as the decimal logarithm of the reciprocal of the hydrogen ion activity, aH+, in a solution. PH = − log 10 = log 10 For example, for a solution with a hydrogen ion activity of 5×10−6 we get 1/ = 2×105, thus such a solution has a pH of log10 = 5.3. For a commonplace example based on the facts that the masses of a mole of water, a mole of hydrogen ions, a mole of hydroxide ions are 18 g, 1 g, 17 g, a quantity of 107 moles of pure water, or 180 tonnes, contains close to 1 g of dissociated hydrogen ions and 17 g of hydroxide ions. Note that pH depends on temperature. For instance at 0 °C the pH of pure water is 7.47.
At 25 °C it's 7.00, at 100 °C it's 6.14. This definition was adopted because ion-selective electrodes, which are used to measure pH, respond to activity. Ideally, electrode potential, E, follows the Nernst equation, for the hydrogen ion can be written as E = E 0 + R T F ln = E 0 − 2.303 R T F pH where E is a measured potential, E0 is the standard electrode potential, R is the gas const
In acid base physiology, the Davenport diagram is a graphical tool, developed by Horace W. Davenport, that allows a clinician or investigator to describe blood bicarbonate concentrations and blood pH following a respiratory and/or metabolic acid-base disturbance; the diagram depicts a three-dimensional surface describing all possible states of chemical equilibria between gaseous carbon dioxide, aqueous bicarbonate and aqueous protons at the physiologically complex interface of the alveoli of the lungs and the alveolar capillaries. Although the surface represented in the diagram is experimentally determined, the Davenport diagram is a conceptual tool, allowing the investigator to envision the effects of physiological changes on blood acid-base chemistry; the Davenport diagram is used in the clinical setting. When a sample of blood is exposed to air, either in the alveoli of the lung or in an in vitro laboratory experiment, carbon dioxide in the air enters into equilibrium with carbon dioxide derivatives and other species in the aqueous solution.
Figure 1 illustrates the most important equilibrium reactions of carbon dioxide in blood relating to acid-base physiology: Note that in this equation, the HB/B- buffer system represents all non-bicarbonate buffers present in the blood, such as hemoglobin in its various protonated and deprotonated states. Because many different non-bicarbonate buffers are present in human blood, the final equilibrium state reached at any given pCO2 is complex and cannot be predicted using theory alone. By depicting experimental results, the Davenport diagram provides a simple approach to describing the behavior of this complex system. Figure 2 shows a Davenport diagram as depicted in textbooks and the literature. To understand how the diagram is to be interpreted, it is helpful to understand how the diagram is derived in the first place. Consider the following experiment. A small sample of blood is taken from a healthy patient and placed in a chamber in which the partial pressure of carbon dioxide is held at 40 mmHg.
Once equilibrium is reached, the pH and bicarbonate concentration are measured and plotted on a chart as in Fig. 3. Next, the PCO2 in the chamber is held constant while the pH of the blood sample is changed, first by adding a strong acid by adding a strong base; as pH is varied, a titration curve for the sample is produced. Notice that this titration curve is valid only at a PCO2 of 40 mmHg, because the chamber was held at this partial pressure throughout the experiment. Next, imagine that the experimenter obtains a new, identical blood sample from the same patient. However, instead of placing the sample in a chamber with a PCO2 of 40 mmHg, the chamber is reset to a PCO2 of 60 mmHg. After equilibration, a new point is reached, indicating a new pH and a new bicarbonate concentration. Note that the bicarbonate concentration at the new, higher PCO2 is larger than in the first measurement, whereas the pH is now smaller. Neither result should come as a surprise. Increasing the PCO2 means that the total amount of carbon dioxide in the system has increased.
Because the gaseous carbon dioxide is in equilibrium with the carbon dioxide derivatives in the solution, the concentrations of carbon dioxide derivatives, including bicarbonate, should increase. The fall in pH is not surprising, since the formation of a bicarbonate molecule is concomitant with the release of a proton. If this same experiment is repeated at various partial pressures of carbon dioxide, a series of points will be obtained. One can draw a line through these points, called the buffer line; the buffer line can be used to predict the result of varying the PCO2 within a range close to the experimentally determined points. Additionally, for each experimental point, a titration experiment can be performed in which pH is varied while PCO2 is held constant, titration curves can be generated for each of the partial pressure of carbon dioxide. In the Davenport diagram, these titration curves are called isopleths, because they are generated at a fixed partial pressure of carbon dioxide. A key concept in understanding the Davenport diagram is to note that as PCO2 is increased, the magnitude of the resulting change in pH is dependent on the buffering power of the non-bicarbonate buffers present in the solution.
If strong non-bicarbonate buffers are present they will absorb the vast majority of protons released by the formation of bicarbonate, pH will change little for a given rise in bicarbonate concentration. The result will be a buffer line with a steep slope. On the other hand, if only weak non-bicarbonate buffers are present a much larger change in pH will be observed for a given change in bicarbonate concentration, the buffer line will have a slope closer to zero, it is instructive to note that the slope of the bicarbonate line will never reach zero under equilibrium conditions in the complete absence of non-bicarbonate buffers. This is because the production of protons resulting from an increase in PCO2 is concomitant with the production of bicarbonate ions, as mentioned previously. Thus, a decrease in pH resulting from increased PCO2 must always occur with some minimal increase in bicarbonate concentration. An increase in pH for similar reasons must occur with some minimal decrease in bicarbonate concentration.
Recall that the relationship represented in a Davenport diagram is a relationship between three variables: PCO2, bicarbonate concentration and pH. Thus, Fig. 7 can be thought of as a topographical map—that is, a two-dimensional representation of a three-dimensional surface—where each isopleth indicates a different pa
The chloride ion is the anion Cl−. It is formed when the element chlorine gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride salts such as sodium chloride are very soluble in water, it is an essential electrolyte located in all body fluids responsible for maintaining acid/base balance, transmitting nerve impulses and regulating fluid in and out of cells. Less the word chloride may form part of the "common" name of chemical compounds in which one or more chlorine atoms are covalently bonded. For example, methyl chloride, with the standard name chloromethane is an organic compound with a covalent C−Cl bond in which the chlorine is not an anion. A chloride ion is much larger than a chlorine atom, 99 pm, respectively; the ion is diamagnetic. In aqueous solution, it is soluble in most cases. In aqueous solution, chloride is bound by the protic end of the water molecules. Sea water contains 1.94% chloride. Some chloride-containing minerals include the chlorides of sodium and magnesium, hydrated MgCl2.
The concentration of chloride in the blood is called serum chloride, this concentration is regulated by the kidneys. A chloride ion is a structural component of e.g. it is present in the amylase enzyme. The chlor-alkali industry is a major consumer of the world's energy budget; this process converts sodium chloride into chlorine and sodium hydroxide, which are used to make many other materials and chemicals. The process involves two parallel reactions: 2 Cl− → Cl2 + 2 e− 2 H2O + 2 e− → H2 + 2 OH− Another major application involving chloride is desalination, which involves the energy intensive removal of chloride salts to give potable water. In the petroleum industry, the chlorides are a monitored constituent of the mud system. An increase of the chlorides in the mud system may be an indication of drilling into a high-pressure saltwater formation, its increase can indicate the poor quality of a target sand. Chloride is a useful and reliable chemical indicator of river / groundwater fecal contamination, as chloride is a non-reactive solute and ubiquitous to sewage & potable water.
Many water regulating companies around the world utilize chloride to check the contamination levels of the rivers and potable water sources. Chloride salts such as sodium chloride are used to preserve food; the presence of chlorides, e.g. in seawater aggravates the conditions for pitting corrosion of most metals by enhancing the formation and growth of the pits through an autocatalytic process. Chloride is an essential electrolyte, trafficking in and out of cells through chloride channels and playing a key role in maintaining cell homeostasis and transmitting action potentials in neurons. Characteristic concentrations of chloride in model organisms are: in both E. coli and budding yeast are 10-200mM, in mammalian cell 5-100mM and in blood plasma 100mM. Chloride can be oxidized but not reduced; the first oxidation, as employed in the chlor-alkali process, is conversion to chlorine gas. Chlorine can be further oxidized to other oxides and oxyanions including hypochlorite, chlorine dioxide and perchlorate.
In terms of its acid–base properties, chloride is a weak base as indicated by the negative value of the pKa of hydrochloric acid. Chloride can be protonated by strong acids, such as sulfuric acid: NaCl + H2SO4 → NaHSO4 + HClIonic chloride salts reaction with other salts to exchange anions; the presence of chloride is detected by its formation of an insoluble silver chloride upon treatment with silver ion: Cl− + Ag+ → AgClThe concentration of chloride in an assay can be determined using a chloridometer, which detects silver ions once all chloride in the assay has precipitated via this reaction. Chlorided silver electrodes are used in ex vivo electrophysiology. An example is table salt, sodium chloride with the chemical formula NaCl. In water, it dissociates into Na Cl − ions. Salts such as calcium chloride, magnesium chloride, potassium chloride have varied uses ranging from medical treatments to cement formation. Calcium chloride is a salt, marketed in pellet form for removing dampness from rooms.
Calcium chloride is used for maintaining unpaved roads and for fortifying roadbases for new construction. In addition, calcium chloride is used as a de-icer, since it is effective in lowering the melting point when applied to ice. Examples of covalently bonded chlorides are phosphorus trichloride, phosphorus pentachloride, thionyl chloride, all three of which are reactive chlorinating reagents that have been used in a laboratory. Chlorine can assume oxidation states of −1, +1, +3, +5, or +7. Several neutral chlorine oxides are known. Halide Renal chloride reabsorption
A hydrogen ion is created when a hydrogen atom loses or gains an electron. A positively charged hydrogen ion can combine with other particles and therefore is only seen isolated when it is in a gaseous state or a nearly particle-free space. Due to its high charge density of 2×1010 times that of a sodium ion, the bare hydrogen ion cannot exist in solution as it hydrates, i.e. bonds quickly. The hydrogen ion is recommended by IUPAC as a general term for all ions of hydrogen and its isotopes. Depending on the charge of the ion, two different classes can be distinguished: positively charged ions and negatively charged ions. A hydrogen atom is made up of a nucleus with charge +1, a single electron. Therefore, the only positively charged ion possible has charge +1, it is noted H+. Depending on the isotope in question, the hydrogen cation has different names: Hydron: general name referring to the positive ion of any hydrogen isotope Proton: 1H+ Deuteron: 2H+, D+ Triton: 3H+, T+In addition, the ions produced by the reaction of these cations with water as well as their hydrates are called hydrogen ions: Hydronium ion: H3O+ Zundel cation: H5O2+ Eigen cation: H9O4+ Zundel cations and Eigen cations play an important role in proton diffusion according to the Grotthuss mechanism.
In connection with acids, "hydrogen ions" refers to hydrons. Hydrogen atom contains a single electron. Removal of the electron gives a cation; the hydrogen anion, with its loosely held two-electron cloud, has a larger radius than the neutral atom, which in turn is much larger than the bare proton of the cation. Hydrogen forms the only cation that has no electrons, but cations that still retain one or more electrons are still smaller than the neutral atoms or molecules from which they are derived. Hydrogen anions are formed when additional electrons are acquired: Hydride: general name referring to the negative ion of any hydrogen isotope Protide: 1H− Deuteride: 2H−, D − Tritide: 3H−, T − Hydrogen ions drive ATP synthase in photosynthesis; this happens when hydrogen ions get pushed across the membrane creating a high concentration inside the thylakoid membrane and a low concentration in the cytoplasm. However, because of osmosis, the H+ will force itself out of the membrane through ATP synthase.
Using their kinetic energy to escape, the protons will spin the ATP synthase which in turn will create ATP. This happens in cellular respiration as well though the concentrated membrane will instead be the inner membrane of the mitochondria. Hydrogen ions concentration, measured as pH, is responsible for the acidic or basic nature of a compound. Water molecules split to form hydroxide anions; this process is referred to as the self-ionization of water. Acid Protonation Dihydrogen cation Trihydrogen cation
Hydrochloric acid or muriatic acid is a colorless inorganic chemical system with the formula H2O:HCl. Hydrochloric acid has a distinctive pungent smell, it is classified as acidic and can attack the skin over a wide composition range, since the hydrogen chloride dissociates in aqueous solution. Hydrochloric acid is the simplest chlorine-based acid system containing water, it is a solution of hydrogen chloride and water, a variety of other chemical species, including hydronium and chloride ions. It is an important chemical reagent and industrial chemical, used in the production of polyvinyl chloride for plastic. In households, diluted hydrochloric acid is used as a descaling agent. In the food industry, hydrochloric acid is used in the production of gelatin. Hydrochloric acid is used in leather processing. Hydrochloric acid was discovered by the alchemist Jabir ibn Hayyan around the year 800 AD, it was called acidum salis and spirits of salt because it was produced from rock salt and "green vitriol" and from the chemically similar common salt and sulfuric acid.
Free hydrochloric acid was first formally described in the 16th century by Libavius. It was used by chemists such as Glauber and Davy in their scientific research. Unless pressurized or cooled, hydrochloric acid will turn into a gas if there is around 60% or less of water. Hydrochloric acid is known as hydronium chloride, in contrast to its anhydrous parent known as hydrogen chloride, or dry HCl. Hydrochloric acid was known to European alchemists as spirits of acidum salis. Both names are still used in other languages, such as German: Salzsäure, Dutch: Zoutzuur, Swedish: Saltsyra, Turkish: Tuz Ruhu, Polish: kwas solny, Bulgarian: солна киселина, Russian: соляная кислота, Chinese: 鹽酸, Korean: 염산, Taiwanese: iâm-sng. Gaseous HCl was called marine acid air; the old name muriatic acid has the same origin, this name is still sometimes used. The name hydrochloric acid was coined by the French chemist Joseph Louis Gay-Lussac in 1814. Hydrochloric acid has been an important and used chemical from early history and was discovered by the alchemist Jabir ibn Hayyan around the year 800 AD.
Aqua regia, a mixture consisting of hydrochloric and nitric acids, prepared by dissolving sal ammoniac in nitric acid, was described in the works of Pseudo-Geber, a 13th-century European alchemist. Other references suggest that the first mention of aqua regia is in Byzantine manuscripts dating to the end of the 13th century. Free hydrochloric acid was first formally described in the 16th century by Libavius, who prepared it by heating salt in clay crucibles. Other authors claim that pure hydrochloric acid was first discovered by the German Benedictine monk Basil Valentine in the 15th century, when he heated common salt and green vitriol, whereas others argue that there is no clear reference to the preparation of pure hydrochloric acid until the end of the 16th century. In the 17th 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, by 1808 Humphry Davy of Penzance, England had proved that the chemical composition included hydrogen and chlorine.
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. In this Leblanc process, common salt is converted to soda ash, using sulfuric acid 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 into the 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 20th century, the Leblanc process was replaced by the Solvay process without a hydrochloric acid by-product. Since hydrochloric acid was 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 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 and methamphetamine. Hydrochloric acid is the salt of H3O + and chloride, it is prepared by treating HCl with water. HCl + H 2 O ⟶ H 3 O + + Cl − However, the speciation of hydrochloric acid is more complicated than this simple equation implies; the structure of bulk water is infamously complex, the formula H3O+ is a gross oversimplification of the true nature of the solvated proton, H+, present in hydrochloric acid. A combined IR, Raman, X-ray and neutron diffraction study of concentrated solutions of hydrochloric acid revealed that the primary form of H+ in these solutions is H5O2+, along with the chloride anion, is hydrogen-bonded to neighboring wa