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85-406: 110862 ENSG00000184156 ENSMUSG00000056258 O43525 Q8K3F6 NM_001204824 NM_004519 NM_152923 NP_001191753 NP_004510 NP_690887 K v 7.3 (KvLQT3) is a potassium channel protein coded for by the gene KCNQ3. It is associated with benign familial neonatal epilepsy . The M channel is a slowly activating and deactivating potassium channel that plays
170-467: A gas diffusion electrode . The amount of electrical energy that must be added equals the change in Gibbs free energy of the reaction plus the losses in the system. The losses can (in theory) be arbitrarily close to zero, so the maximum thermodynamic efficiency equals the enthalpy change divided by the free energy change of the reaction. In most cases, the electric input is larger than the enthalpy change of
255-423: A lilac color with a peak emission wavelength of 766.5 nanometers. Neutral potassium atoms have 19 electrons, one more than the configuration of the noble gas argon . Because of its low first ionization energy of 418.8 kJ/mol, the potassium atom is much more likely to lose the last electron and acquire a positive charge, although negatively charged alkalide K ions are not impossible. In contrast,
340-508: A cause of benign familial neonatal convulsions type 2 (BFNC2), also known as epilepsy, benign neonatal type 2 (EBN2). KvLQT3 has been shown to interact with KCNQ5 . This article incorporates text from the United States National Library of Medicine , which is in the public domain . This membrane protein –related article is a stub . You can help Misplaced Pages by expanding it . Potassium Potassium
425-404: A compound, electrical energy is released. Humphry Davy would go on to create Decomposition Tables from his preliminary experiments on Electrolysis. The Decomposition Tables would give insight on the energies needed to break apart certain compounds. In 1817 Johan August Arfwedson determined there was another element, lithium, in some of his samples; however, he could not isolate the component. It
510-449: A critical role in the regulation of neuronal excitability. The M channel is formed by the association of the protein encoded by this gene and one of two related proteins encoded by the KCNQ2 and KCNQ5 genes, both integral membrane proteins. M channel currents are inhibited by M1 muscarinic acetylcholine receptors and activated by retigabine , a novel anti-convulsant drug. Defects in this gene are
595-475: A distance such that a current flows between them through the electrolyte and are connected to the power source which completes the electrical circuit . A direct current supplied by the power source drives the reaction causing ions in the electrolyte to be attracted toward the respective oppositely charged electrode. Electrodes of metal , graphite and semiconductor material are widely used. Choice of suitable electrode depends on chemical reactivity between
680-667: A gaseous fluorine pure element. Before he used hydrogen fluoride, Henri Moissan used fluoride salts with electrolysis. Thus on June 28, 1886, he performed his experiment in front of the Académie des sciences to show his discovery of the new element fluorine. While trying to find elemental fluorine through electrolysis of fluoride salts, many chemists perished including Paulin Louyet and Jérôme Nicklès. In 1886 Charles Martin Hall from America and Paul Héroult from France both filed for American patents for
765-400: A human body of 70 kg, about 4,400 nuclei of K decay per second. The activity of natural potassium is 31 Bq /g. Potash is primarily a mixture of potassium salts because plants have little or no sodium content, and the rest of a plant's major mineral content consists of calcium salts of relatively low solubility in water. While potash has been used since ancient times, its composition
850-463: A permanent mark or logo. Using a cell containing inert platinum electrodes, electrolysis of aqueous solutions of some salts leads to the reduction of the cations (such as metal deposition with, for example, zinc salts) and oxidation of the anions (such as the evolution of bromine with bromides). However, with salts of some metals (such as sodium) hydrogen is evolved at the cathode, and for salts containing some anions (such as sulfate SO 4 ) oxygen
935-400: A plant salt, by a similar technique, demonstrating that the elements, and thus the salts, are different. Although the production of potassium and sodium metal should have shown that both are elements, it took some time before this view was universally accepted. Because of the sensitivity of potassium to water and air, air-free techniques are normally employed for handling the element. It
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#17328907993011020-577: A process later known as electrolysis. Though he unknowingly produced electrolysis, it was not until 1800 when William Nicholson and Anthony Carlisle discovered how electrolysis works. In 1791 Luigi Galvani experimented with frog legs. He claimed that placing animal muscle between two dissimilar metal sheets resulted in electricity. Responding to these claims, Alessandro Volta conducted his own tests. This would give insight to Humphry Davy 's ideas on electrolysis. During preliminary experiments, Humphry Davy hypothesized that when two elements combine to form
1105-437: A product out of the electrolyte). The quantity of the products is proportional to the current, and when two or more electrolytic cells are connected in series to the same power source, the products produced in the cells are proportional to their equivalent weight . These are known as Faraday's laws of electrolysis . Each electrode attracts ions that are of the opposite charge . Positively charged ions ( cations ) move towards
1190-486: A variety of graphite intercalation compounds , including KC 8 . There are 25 known isotopes of potassium, three of which occur naturally: K (93.3%), K (0.0117%), and K (6.7%) (by mole fraction). Naturally occurring K has a half-life of 1.250 × 10 years. It decays to stable Ar by electron capture or positron emission (11.2%) or to stable Ca by beta decay (88.8%). The decay of K to Ar
1275-477: A wide variety of proteins and enzymes. Potassium levels influence multiple physiological processes, including Potassium homeostasis denotes the maintenance of the total body potassium content, plasma potassium level, and the ratio of the intracellular to extracellular potassium concentrations within narrow limits, in the face of pulsatile intake (meals), obligatory renal excretion, and shifts between intracellular and extracellular compartments. Plasma potassium
1360-418: Is potassium cobaltinitrite , K 3 [Co(NO 2 ) 6 ] , which is used as artist's pigment under the name of Aureolin or Cobalt Yellow. The stable isotopes of potassium can be laser cooled and used to probe fundamental and technological problems in quantum physics . The two bosonic isotopes possess convenient Feshbach resonances to enable studies requiring tunable interactions, while K
1445-400: Is a chemical element ; it has symbol K (from Neo-Latin kalium ) and atomic number 19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to form flaky white potassium peroxide in only seconds of exposure. It was first isolated from potash , the ashes of plants, from which its name derives. In
1530-469: Is a macronutrient required for life on Earth. K occurs in natural potassium (and thus in some commercial salt substitutes) in sufficient quantity that large bags of those substitutes can be used as a radioactive source for classroom demonstrations. K is the radioisotope with the largest abundance in the human body . In healthy animals and people, K represents the largest source of radioactivity, greater even than C . In
1615-493: Is a strong base . Illustrating its hydrophilic character, as much as 1.21 kg of KOH can dissolve in a single liter of water. Anhydrous KOH is rarely encountered. KOH reacts readily with carbon dioxide ( CO 2 ) to produce potassium carbonate ( K 2 CO 3 ), and in principle could be used to remove traces of the gas from air. Like the closely related sodium hydroxide , KOH reacts with fats to produce soaps . In general, potassium compounds are ionic and, owing to
1700-406: Is a main constituent of some varieties of baking powder ; it is also used in the silvering of mirrors. Potassium bromate ( KBrO 3 ) is a strong oxidizer (E924), used to improve dough strength and rise height. Potassium bisulfite ( KHSO 3 ) is used as a food preservative, for example in wine and beer -making (but not in meats). It is also used to bleach textiles and straw, and in
1785-454: Is a necessary element for plants and that most types of soil lack potassium caused a steep rise in demand for potassium salts. Wood-ash from fir trees was initially used as a potassium salt source for fertilizer, but, with the discovery in 1868 of mineral deposits containing potassium chloride near Staßfurt , Germany, the production of potassium-containing fertilizers began at an industrial scale. Other potash deposits were discovered, and by
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#17328907993011870-505: Is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction . Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell . The voltage that is needed for electrolysis to occur is called the decomposition potential. The word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity." The word "electrolysis"
1955-668: Is accelerated by minute amounts of transition metal salts. Because it can reduce the salts to the metal, potassium is often used as the reductant in the preparation of finely divided metals from their salts by the Rieke method . Illustrative is the preparation of magnesium: Potassium is formed in supernovae by nucleosynthesis from lighter atoms. Potassium is principally created in Type II supernovae via an explosive oxygen-burning process . These are nuclear fusion reactions, not to be confused with chemical burning of potassium in oxygen. K
2040-516: Is also formed in s-process nucleosynthesis and the neon burning process . Potassium is the 20th most abundant element in the solar system and the 17th most abundant element by weight in the Earth. It makes up about 2.6% of the weight of the Earth's crust and is the seventh most abundant element in the crust. The potassium concentration in seawater is 0.39 g/L (0.039 wt/v%), about one twenty-seventh
2125-448: Is also used in organic synthesis to make nitriles . Potassium carbonate ( K 2 CO 3 or potash) is used in the manufacture of glass, soap, color TV tubes, fluorescent lamps, textile dyes and pigments. Potassium permanganate ( KMnO 4 ) is an oxidizing, bleaching and purification substance and is used for production of saccharin . Potassium chlorate ( KClO 3 ) is added to matches and explosives. Potassium bromide (KBr)
2210-433: Is also used in some mines. The resulting sodium and magnesium waste is either stored underground or piled up in slag heaps . Most of the mined potassium mineral ends up as potassium chloride after processing. The mineral industry refers to potassium chloride either as potash, muriate of potash, or simply MOP. Pure potassium metal can be isolated by electrolysis of its hydroxide in a process that has changed little since it
2295-460: Is altered in the process. For example, the electrolysis of brine produces hydrogen and chlorine gases which bubble from the electrolyte and are collected. The initial overall reaction is thus: The reaction at the anode results in chlorine gas from chlorine ions: The reaction at the cathode results in hydrogen gas and hydroxide ions: Without a partition between the electrodes, the OH ions produced at
2380-495: Is charged, its redox reaction is run in reverse and the system can be considered as an electrolytic cell . The chloralkali process is a large scale application of electrolysis. This technology supplies most of the chlorine and sodium hydroxide required by many industries. The cathode is a mixed metal oxide clad titanium anode (also called a dimensionally stable anode). Many organofluorine compounds are produced by electrofluorination . One manifestation of this technology
2465-414: Is deposited over a substrate material. Electroplating is used in many industries for either functional or decorative purposes, as in-vehicle bodies and nickel coins. In Electrochemical machining , an electrolytic cathode is used as a shaped tool for removing material by anodic oxidation from a workpiece. ECM is often used as a technique for deburring or for etching metal surfaces like tools or knives with
2550-475: Is evolved at the anode. In both cases, this is due to water being reduced to form hydrogen or oxidized to form oxygen. In principle, the voltage required to electrolyze a salt solution can be derived from the standard electrode potential for the reactions at the anode and cathode. The standard electrode potential is directly related to the Gibbs free energy , Δ G , for the reactions at each electrode and refers to an electrode with no current flowing. An extract from
2635-507: Is illustrative: The potassium cobaltinitrite is obtained as a yellow solid. Potassium ions are an essential component of plant nutrition and are found in most soil types. They are used as a fertilizer in agriculture , horticulture , and hydroponic culture in the form of chloride (KCl), sulfate ( K 2 SO 4 ), or nitrate ( KNO 3 ), representing the 'K' in 'NPK' . Agricultural fertilizers consume 95% of global potassium chemical production, and about 90% of this potassium
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2720-570: Is mined in Canada , Russia , Belarus , Kazakhstan , Germany , Israel , the U.S., Jordan , and other places around the world. The first mined deposits were located near Staßfurt, Germany, but the deposits span from Great Britain over Germany into Poland. They are located in the Zechstein and were deposited in the Middle to Late Permian . The largest deposits ever found lie 1,000 meters (3,300 feet) below
2805-422: Is normally kept at 3.5 to 5.5 millimoles (mmol) [or milliequivalents (mEq)] per liter by multiple mechanisms. Levels outside this range are associated with an increasing rate of death from multiple causes, and some cardiac, kidney, and lung diseases progress more rapidly if serum potassium levels are not maintained within the normal range. Electrolysis In chemistry and manufacturing , electrolysis
2890-494: Is obtained from natural sources such as guano and evaporites or manufactured via the Haber process ; it is the oxidant in gunpowder ( black powder ) and an important agricultural fertilizer. Potassium cyanide (KCN) is used industrially to dissolve copper and precious metals, in particular silver and gold , by forming complexes . Its applications include gold mining , electroplating , and electroforming of these metals ; it
2975-401: Is one of only two stable fermions amongst the alkali metals. An alloy of sodium and potassium, NaK is a liquid used as a heat-transfer medium and a desiccant for producing dry and air-free solvents . It can also be used in reactive distillation . The ternary alloy of 12% Na, 47% K and 41% Cs has the lowest melting point of −78 °C of any metallic compound. Metallic potassium
3060-434: Is optional to keep the products from diffusing to the vicinity of the opposite electrode. The electrolyte is a chemical substance which contains free ions and carries electric current (e.g. an ion-conducting polymer , solution, or a ionic liquid compound). If the ions are not mobile, as in most solid salts , then electrolysis cannot occur. A liquid electrolyte is produced by: The electrodes are immersed separated by
3145-429: Is produced mostly by decomposition of the complex minerals kainite ( MgSO 4 ·KCl·3H 2 O ) and langbeinite ( MgSO 4 ·K 2 SO 4 ). Only a very few fertilizers contain potassium nitrate. In 2005, about 93% of world potassium production was consumed by the fertilizer industry. Furthermore, potassium can play a key role in nutrient cycling by controlling litter composition. Potassium citrate
3230-435: Is supplied as KCl. The potassium content of most plants ranges from 0.5% to 2% of the harvested weight of crops, conventionally expressed as amount of K 2 O . Modern high- yield agriculture depends upon fertilizers to replace the potassium lost at harvest. Most agricultural fertilizers contain potassium chloride, while potassium sulfate is used for chloride-sensitive crops or crops needing higher sulfur content. The sulfate
3315-458: Is the Simons process , which can be described as: In the course of a typical synthesis, this reaction occurs once for each C–H bond in the precursor. The cell potential is maintained near 5–6 V . The anode , the electrocatalyst, is nickel -plated. Acrylonitrile is converted to adiponitrile on an industrial scale via electrocatalysis. Electroplating , where a thin film of metal
3400-770: Is the basis of a common method for dating rocks. The conventional K-Ar dating method depends on the assumption that the rocks contained no argon at the time of formation and that all the subsequent radiogenic argon ( Ar ) was quantitatively retained. Minerals are dated by measurement of the concentration of potassium and the amount of radiogenic Ar that has accumulated. The minerals best suited for dating include biotite , muscovite , metamorphic hornblende , and volcanic feldspar ; whole rock samples from volcanic flows and shallow instrusives can also be dated if they are unaltered. Apart from dating, potassium isotopes have been used as tracers in studies of weathering and for nutrient cycling studies because potassium
3485-450: Is the difference of the electrode potentials as calculated using the Nernst equation . Applying additional voltage, referred to as overpotential , can increase the rate of reaction and is often needed above the thermodynamic value. It is especially necessary for electrolysis reactions involving gases, such as oxygen , hydrogen or chlorine . Oxidation of ions or neutral molecules occurs at
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3570-410: Is unreactive toward nitrogen and saturated hydrocarbons such as mineral oil or kerosene . It readily dissolves in liquid ammonia , up to 480 g per 1000 g of ammonia at 0 °C. Depending on the concentration, the ammonia solutions are blue to yellow, and their electrical conductivity is similar to that of liquid metals. Potassium slowly reacts with ammonia to form KNH 2 , but this reaction
3655-415: Is used in several types of magnetometers . Potassium is the eighth or ninth most common element by mass (0.2%) in the human body, so that a 60 kg adult contains a total of about 120 g of potassium. The body has about as much potassium as sulfur and chlorine, and only calcium and phosphorus are more abundant (with the exception of the ubiquitous CHON elements). Potassium ions are present in
3740-410: Is used to treat a kidney stone condition called renal tubular acidosis . Potassium, in the form of potassium chloride is used as a medication to treat and prevent low blood potassium . Low blood potassium may occur due to vomiting , diarrhea , or certain medications. It is given by slow injection into a vein or by mouth. Potassium sodium tartrate ( KNaC 4 H 4 O 6 , Rochelle salt )
3825-455: The Dead Sea is used by Israel and Jordan as a source of potash, while the concentration in normal oceans is too low for commercial production at current prices. Several methods are used to separate potassium salts from sodium and magnesium compounds. The most-used method is fractional precipitation using the solubility differences of the salts. Electrostatic separation of the ground salt mixture
3910-471: The International Union of Pure and Applied Chemistry has designated the official chemical symbol as K . Potassium is the second least dense metal after lithium . It is a soft solid with a low melting point , and can be easily cut with a knife. Potassium is silvery in appearance, but it begins to tarnish toward gray immediately on exposure to air. In a flame test , potassium and its compounds emit
3995-451: The anode . For example, it is possible to oxidize ferrous ions to ferric ions at the anode: Reduction of ions or neutral molecules occurs at the cathode . It is possible to reduce ferricyanide ions to ferrocyanide ions at the cathode: Neutral molecules can also react at either of the electrodes. For example: p -benzoquinone can be reduced to hydroquinone at the cathode: In the last example, H ions (hydrogen ions) also take part in
4080-411: The chromate ion rather than to that of the potassium ion. There are thousands of uses of various potassium compounds. One example is potassium superoxide , KO 2 , an orange solid that acts as a portable source of oxygen and a carbon dioxide absorber. It is widely used in respiration systems in mines, submarines and spacecraft as it takes less volume than the gaseous oxygen. Another example
4165-414: The periodic table , potassium is one of the alkali metals , all of which have a single valence electron in the outer electron shell, which is easily removed to create an ion with a positive charge (which combines with anions to form salts ). In nature, potassium occurs only in ionic salts. Elemental potassium reacts vigorously with water, generating sufficient heat to ignite hydrogen emitted in
4250-424: The 1960s Canada became the dominant producer. Potassium metal was first isolated in 1807 by Humphry Davy, who derived it by electrolysis of molten caustic potash (KOH) with the newly discovered voltaic pile . Potassium was the first metal that was isolated by electrolysis. Later in the same year, Davy reported extraction of the metal sodium from a mineral derivative ( caustic soda , NaOH, or lye) rather than
4335-434: The alkali in his list of chemical elements in 1789. For a long time the only significant applications for potash were the production of glass, bleach, soap and gunpowder as potassium nitrate. Potassium soaps from animal fats and vegetable oils were especially prized because they tend to be more water-soluble and of softer texture, and are therefore known as soft soaps. The discovery by Justus Liebig in 1840 that potassium
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#17328907993014420-451: The cathode are free to diffuse throughout the electrolyte to the anode. As the electrolyte becomes more basic due to the production of OH , less Cl 2 emerges from the solution as it begins to react with the hydroxide producing hypochlorite (ClO ) at the anode: The more opportunity the Cl 2 has to interact with NaOH in the solution, the less Cl 2 emerges at the surface of the solution and
4505-427: The cathode, the rate of the latter depends on factors such as diffusion and the surface area of the cathode in contact with the electrolyte. Decomposition potential or decomposition voltage refers to the minimum voltage (difference in electrode potential ) between anode and cathode of an electrolytic cell that is needed for electrolysis to occur. The voltage at which electrolysis is thermodynamically preferred
4590-513: The concentration of sodium. Elemental potassium does not occur in nature because of its high reactivity. It reacts violently with water and also reacts with oxygen. Orthoclase (potassium feldspar) is a common rock-forming mineral. Granite for example contains 5% potassium, which is well above the average in the Earth's crust. Sylvite (KCl), carnallite ( KCl·MgCl 2 ·6H 2 O ), kainite ( MgSO 4 ·KCl·3H 2 O ) and langbeinite ( MgSO 4 ·K 2 SO 4 ) are
4675-513: The early nineteenth century, William Nicholson and Anthony Carlisle sought to further Volta's experiments. They attached two wires to either side of a voltaic pile and placed the other ends in a tube filled with water. They noticed when the wires were brought together that each wire produced bubbles. One type was hydrogen, the other was oxygen. In 1785 a Dutch scientist named Martin van Marum created an electrostatic generator that he used to reduce tin, zinc and antimony from their salts using
4760-484: The electrode and electrolyte and manufacturing cost. Historically, when non-reactive anodes were desired for electrolysis, graphite (called plumbago in Faraday's time) or platinum were chosen. They were found to be some of the least reactive materials for anodes. Platinum erodes very slowly compared to other materials, and graphite crumbles and can produce carbon dioxide in aqueous solutions but otherwise does not participate in
4845-409: The electrolysis of copper and zinc . Electrolysis is the passing of a direct electric current through an electrolyte which is producing chemical reactions at the electrodes and decomposition of the materials. The main components required to achieve electrolysis are an electrolyte , electrodes, and an external power source. A partition (e.g. an ion-exchange membrane or a salt bridge )
4930-713: The electrolysis of aluminum, with Héroult submitting his in May, and Hall, in July. Hall was able to get his patent by proving through letters to his brother and family evidence that his method was discovered before the French patent was submitted. This became known as the Hall–Héroult process which benefited many industries because aluminum's price then dropped from four dollars to thirty cents per pound. In 1902 Polish engineer and inventor Stanisław Łaszczyński filed for and obtained Polish patent for
5015-413: The electron-providing (negative) cathode. Negatively charged ions ( anions ) move towards the electron-extracting (positive) anode. In this process electrons are effectively introduced at the cathode as a reactant and removed at the anode as a product . In chemistry, the loss of electrons is called oxidation , while electron gain is called reduction . When neutral atoms or molecules, such as those on
5100-435: The element potassium comes from the word potash , which refers to an early method of extracting various potassium salts: placing in a pot the ash of burnt wood or tree leaves, adding water, heating, and evaporating the solution. When Humphry Davy first isolated the pure element using electrolysis in 1807, he named it potassium , which he derived from the word potash . The symbol K stems from kali , itself from
5185-402: The faster the production of hypochlorite progresses. This depends on factors such as solution temperature, the amount of time the Cl 2 molecule is in contact with the solution, and concentration of NaOH. Likewise, as hypochlorite increases in concentration, chlorates are produced from them: Other reactions occur, such as the self-ionization of water and the decomposition of hypochlorite at
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#17328907993015270-608: The formation of a surface layer of potassium superoxide , a pressure-sensitive explosive that detonates when scratched. The resulting explosion often starts a fire difficult to extinguish. Potassium is now quantified by ionization techniques, but at one time it was quantitated by gravimetric analysis . Reagents used to precipitate potassium salts include sodium tetraphenylborate , hexachloroplatinic acid , and sodium cobaltinitrite into respectively potassium tetraphenylborate , potassium hexachloroplatinate , and potassium cobaltinitrite . The reaction with sodium cobaltinitrite
5355-595: The high hydration energy of the K ion, have excellent water solubility. The main species in water solution are the aquo complexes [K(H 2 O) n ] where n = 6 and 7. Potassium heptafluorotantalate ( K 2 [TaF 7 ] ) is an intermediate in the purification of tantalum from the otherwise persistent contaminant of niobium . Organopotassium compounds illustrate nonionic compounds of potassium. They feature highly polar covalent K–C bonds. Examples include benzyl potassium KCH 2 C 6 H 5 . Potassium intercalates into graphite to give
5440-439: The human body. Potassium ions are vital for the functioning of all living cells. The transfer of potassium ions across nerve cell membranes is necessary for normal nerve transmission; potassium deficiency and excess can each result in numerous signs and symptoms, including an abnormal heart rhythm and various electrocardiographic abnormalities. Fresh fruits and vegetables are good dietary sources of potassium. The body responds to
5525-523: The influx of dietary potassium, which raises serum potassium levels, by shifting potassium from outside to inside cells and increasing potassium excretion by the kidneys. Most industrial applications of potassium exploit the high solubility of its compounds in water, such as saltwater soap . Heavy crop production rapidly depletes the soil of potassium, and this can be remedied with agricultural fertilizers containing potassium, accounting for 95% of global potassium chemical production. The English name for
5610-706: The minerals found in large evaporite deposits worldwide. The deposits often show layers starting with the least soluble at the bottom and the most soluble on top. Deposits of niter ( potassium nitrate ) are formed by decomposition of organic material in contact with atmosphere, mostly in caves; because of the good water solubility of niter the formation of larger deposits requires special environmental conditions. Potassium salts such as carnallite , langbeinite , polyhalite , and sylvite form extensive evaporite deposits in ancient lake bottoms and seabeds , making extraction of potassium salts in these environments commercially viable. The principal source of potassium – potash –
5695-485: The name Kalium for Davy's "potassium". In 1814, the Swedish chemist Berzelius advocated the name kalium for potassium, with the chemical symbol K . The English and French-speaking countries adopted the name Potassium , which was favored by Davy and French chemists Joseph Louis Gay-Lussac and Louis Jacques Thénard , whereas the other Germanic countries adopted Gilbert and Klaproth's name Kalium . The "Gold Book" of
5780-406: The ratio of ozone to oxygen produced at the anode in the electrolysis of an aqueous acidic solution such as dilute sulphuric acid. Electrolysis of ethanol with pulsed current evolves an aldehyde instead of primarily an acid. Galvanic cells and batteries use spontaneous, energy-releasing redox reactions to generate an electrical potential that provides useful power. When a secondary battery
5865-439: The reaction and are provided by the acid in the solution, or by the solvent itself (water, methanol, etc.). Electrolysis reactions involving H ions are fairly common in acidic solutions. In aqueous alkaline solutions, reactions involving OH (hydroxide ions) are common. Sometimes the solvents themselves (usually water) are oxidized or reduced at the electrodes. It is even possible to have electrolysis involving gases, e.g. by using
5950-418: The reaction of potassium fluoride with calcium carbide was also used to produce potassium. Reagent-grade potassium metal costs about $ 10.00/ pound ($ 22/ kg ) in 2010 when purchased by the tonne . Lower purity metal is considerably cheaper. The market is volatile because long-term storage of the metal is difficult. It must be stored in a dry inert gas atmosphere or anhydrous mineral oil to prevent
6035-468: The reaction, and burning with a lilac - colored flame . It is found dissolved in seawater (which is 0.04% potassium by weight), and occurs in many minerals such as orthoclase , a common constituent of granites and other igneous rocks . Potassium is chemically very similar to sodium , the previous element in group 1 of the periodic table. They have a similar first ionization energy , which allows for each atom to give up its sole outer electron. It
6120-438: The reaction, so some energy is released in the form of heat. In some cases, for instance, in the electrolysis of steam into hydrogen and oxygen at high temperature, the opposite is true and heat energy is absorbed. This heat is absorbed from the surroundings, and the heating value of the produced hydrogen is higher than the electric input. Pulsating current results in products different from DC. For example, pulsing increases
6205-502: The reaction. Cathodes may be made of the same material, or they may be made from a more reactive one since anode wear is greater due to oxidation at the anode. The key process of electrolysis is the interchange of atoms and ions by the removal or addition of electrons due to the applied potential. The desired products of electrolysis are often in a different physical state from the electrolyte and can be removed by mechanical processes (e.g. by collecting gas above an electrode or precipitating
6290-547: The root word alkali , which in turn comes from Arabic : القَلْيَه al-qalyah 'plant ashes'. In 1797, the German chemist Martin Klaproth discovered "potash" in the minerals leucite and lepidolite , and realized that "potash" was not a product of plant growth but actually contained a new element, which he proposed calling kali . In 1807, Humphry Davy produced the element via electrolysis: in 1809, Ludwig Wilhelm Gilbert proposed
6375-775: The second ionization energy is very high (3052 kJ/mol). Potassium reacts with oxygen, water, and carbon dioxide components in air. With oxygen it forms potassium peroxide . With water potassium forms potassium hydroxide (KOH). The reaction of potassium with water can be violently exothermic , especially since the coproduced hydrogen gas can ignite. Because of this, potassium and the liquid sodium-potassium ( NaK ) alloy are potent desiccants , although they are no longer used as such. Four oxides of potassium are well studied: potassium oxide ( K 2 O ), potassium peroxide ( K 2 O 2 ), potassium superoxide ( KO 2 ) and potassium ozonide ( KO 3 ). The binary potassium-oxygen compounds react with water forming KOH. KOH
6460-482: The surface of an electrode, gain or lose electrons they become ions and may dissolve in the electrolyte and react with other ions. When ions gain or lose electrons and become neutral, they will form compounds that separate from the electrolyte. Positive metal ions like Cu deposit onto the cathode in a layer. The terms for this are electroplating , electrowinning , and electrorefining . When an ion gains or loses electrons without becoming neutral, its electronic charge
6545-790: The surface of the Canadian province of Saskatchewan . The deposits are located in the Elk Point Group produced in the Middle Devonian . Saskatchewan, where several large mines have operated since the 1960s pioneered the technique of freezing of wet sands (the Blairmore formation) to drive mine shafts through them. The main potash mining company in Saskatchewan until its merge was the Potash Corporation of Saskatchewan , now Nutrien . The water of
6630-517: The tanning of leathers . Major potassium chemicals are potassium hydroxide, potassium carbonate, potassium sulfate, and potassium chloride. Megatons of these compounds are produced annually. KOH is a strong base, which is used in industry to neutralize strong and weak acids , to control pH and to manufacture potassium salts . It is also used to saponify fats and oils , in industrial cleaners, and in hydrolysis reactions, for example of esters . Potassium nitrate ( KNO 3 ) or saltpeter
6715-610: The time of Maxwell and Faraday, concerns came about for electropositive and electronegative activities. In November 1875, Paul Émile Lecoq de Boisbaudran discovered gallium using electrolysis of gallium hydroxide, producing 3.4 mg of gallium. The following December, he presented his discovery of gallium to the Académie des sciences in Paris. On June 26, 1886, Ferdinand Frederick Henri Moissan finally felt comfortable performing electrolysis on anhydrous hydrogen fluoride to create
6800-409: Was first suggested in 1702 that they were distinct elements that combine with the same anions to make similar salts, which was demonstrated in 1807 when elemental potassium was first isolated via electrolysis . Naturally occurring potassium is composed of three isotopes , of which K is radioactive . Traces of K are found in all potassium, and it is the most common radioisotope in
6885-443: Was first used by Humphry Davy in 1807. Although the electrolysis process was developed and used in industrial scale in the 1920s, the thermal method by reacting sodium with potassium chloride in a chemical equilibrium reaction became the dominant method in the 1950s. The production of sodium potassium alloys is accomplished by changing the reaction time and the amount of sodium used in the reaction. The Griesheimer process employing
6970-403: Was formerly used as a sedative and in photography. While potassium chromate ( K 2 CrO 4 ) is used in the manufacture of a host of different commercial products such as inks , dyes , wood stains (by reacting with the tannic acid in wood), explosives , fireworks , fly paper , and safety matches , as well as in the tanning of leather, all of these uses are due to the chemistry of
7055-460: Was introduced by Michael Faraday in 1834, using the Greek words ἤλεκτρον [ɛ̌ːlektron] "amber", which since the 17th century was associated with electrical phenomena , and λύσις [lýsis] meaning "dissolution". Nevertheless, electrolysis, as a tool to study chemical reactions and obtain pure elements , precedes the coinage of the term and formal description by Faraday. In
7140-433: Was not understood. Georg Ernst Stahl obtained experimental evidence that led him to suggest the fundamental difference of sodium and potassium salts in 1702, and Henri Louis Duhamel du Monceau was able to prove this difference in 1736. The exact chemical composition of potassium and sodium compounds, and the status as chemical element of potassium and sodium, was not known then, and thus Antoine Lavoisier did not include
7225-454: Was not until 1821 that William Thomas Brande used electrolysis to single it out. Two years later, he streamlined the process using lithium chloride and potassium chloride with electrolysis to produce lithium and lithium hydroxide. During the later years of Humphry Davy's research, Michael Faraday became his assistant. While studying the process of electrolysis under Humphry Davy, Michael Faraday discovered two laws of electrolysis . During
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