Potassium

chemical element with atomic number 19

Potassium,  ₁₉K

Potassium pearls (in paraffin oil, ~5 mm each)
General properties
Pronunciation	/pəˈtæsiəm/ ​(pə-TAS-ee-əm)
Appearance	silvery gray
Standard atomic weight.mw-parser-output .nobold{font-weight:normal} (Ar, standard)	7001390983000000000♠39.0983(1)[1]
Potassium in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Na ↑ K ↓ Rb argon ← potassium → calcium
Atomic number (Z)	19
Group	group 1 (alkali metals)
Period	period 4
Block	s-block
Element category	alkali metal
Electron configuration	[Ar] 4s1
Electrons per shell	2, 8, 8, 1
Physical properties
Phase at STP	solid
Melting point	336.7 K ​(63.5 °C, ​146.3 °F)
Boiling point	1032 K ​(759 °C, ​1398 °F)
Density (near r.t.)	0.862 g/cm3
when liquid (at m.p.)	0.828 g/cm3
Critical point	2223 K, 16 MPa[2]
Heat of fusion	2.33 kJ/mol
Heat of vaporization	76.9 kJ/mol
Molar heat capacity	29.6 J/(mol·K)
Atomic properties
Oxidation states	−1, +1 (a strongly basic oxide)
Electronegativity	Pauling scale: 0.82
Ionization energies	1st: 418.8 kJ/mol 2nd: 3052 kJ/mol 3rd: 4420 kJ/mol (more)
Atomic radius	empirical: 227 pm
Covalent radius	203±12 pm
Van der Waals radius	275 pm
Spectral lines of potassium
Other properties
Crystal structure	​body-centered cubic (bcc)
Speed of sound thin rod	2000 m/s (at 20 °C)
Thermal expansion	83.3 µm/(m·K) (at 25 °C)
Thermal conductivity	102.5 W/(m·K)
Electrical resistivity	72 nΩ·m (at 20 °C)
Magnetic ordering	paramagnetic[3]
Magnetic susceptibility	+20.8·10−6 cm3/mol (298 K)[4]
Young's modulus	3.53 GPa
Shear modulus	1.3 GPa
Bulk modulus	3.1 GPa
Mohs hardness	0.4
Brinell hardness	0.363 MPa
CAS Number	7440-09-7
History
Discovery and first isolation	Humphry Davy (1807)
Main isotopes of potassium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct 39K 93.258% stable 40K 0.012% 1.248×109 y β− 40Ca ε 40Ar β+ 40Ar 41K 6.730% stable
view talk edit | references

Potassium is a chemical element with symbol K (from Neo-Latin kalium) and atomic number 19. It was first isolated from potash, the ashes of plants, from which its name derives. In the periodic table, potassium is one of the alkali metals. All of the alkali metals have a single valence electron in the outer electron shell, which is easily removed to create an ion with a positive charge – a cation, which combines with anions to form salts. Potassium in nature occurs only in ionic salts. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and reacts vigorously with water, generating sufficient heat to ignite hydrogen emitted in the reaction, and burning with a lilac-colored flame. It is found dissolved in sea water (which is 0.04% potassium by weight^[5][6]), and is part of many minerals.

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. That they are different elements that combine with the same anions to make similar salts was suspected in 1702,^[7] and was proven in 1807 using electrolysis. Naturally occurring potassium is composed of three isotopes, of which ⁴⁰
K is radioactive. Traces of ⁴⁰
K are found in all potassium, and it is the most common radioisotope in the human body.

Potassium ions are vital for the functioning of all living cells. The transfer of potassium ions through 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 the influx of dietary potassium, which raises serum potassium levels, with a shift of potassium from outside to inside cells and an increase in potassium excretion by the kidneys.

Most industrial applications of potassium exploit the high solubility in water of potassium compounds, such as potassium soaps. 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.^[8]

Contents

• 
  1 Etymology
  


• 
  2 Properties
  
  
  
  • 
    2.1 Physical
    
  
  
  • 
    2.2 Chemical
    
    
    
    • 
      2.2.1 Compounds
      
    
    
    
    
  
  
  • 
    2.3 Isotopes
    
  
  
  
  


• 
  3 Cosmic formation and distribution
  


• 
  4 Potash
  


• 
  5 Metal
  


• 
  6 Geology
  


• 
  7 Biological role
  
  
  
  • 
    7.1 Biochemical function
    
  
  
  • 
    7.2 Homeostasis
    
    
    
    • 
      7.2.1 Plasma levels
      
    
    
    • 
      7.2.2 Control mechanisms
      
    
    
    • 
      7.2.3 Renal filtration, reabsorption, and excretion
      
    
    
    
    
  
  
  
  


• 
  8 Nutrition
  
  
  
  • 
    8.1 Dietary recommendations
    
  
  
  • 
    8.2 Food sources
    
  
  
  • 
    8.3 Deficient intake
    
  
  
  • 
    8.4 Supplementation
    
  
  
  • 
    8.5 Detection by taste buds
    
  
  
  
  


• 
  9 Commercial production
  
  
  
  • 
    9.1 Mining
    
  
  
  • 
    9.2 Chemical extraction
    
  
  
  
  


• 
  10 Commercial uses
  
  
  
  • 
    10.1 Fertilizer
    
  
  
  • 
    10.2 Medical use
    
  
  
  • 
    10.3 Food additives
    
  
  
  • 
    10.4 Industrial
    
    
    
    • 
      10.4.1 Niche uses
      
    
    
    • 
      10.4.2 Laboratory uses
      
    
    
    
    
  
  
  
  


• 
  11 Precautions
  


• 
  12 See also
  


• 
  13 References
  


• 
  14 Bibliography
  


• 
  15 External links
  

Etymology

The English name for the element potassium comes from the word "potash",^[9] 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 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 to call kali.^[10] In 1807, Humphry Davy produced the element via electrolysis: in 1809, Ludwig Wilhelm Gilbert proposed the name Kalium for Davy's "potassium".^[11] In 1814, the Swedish chemist Berzelius advocated the name kalium for potassium, with the chemical symbol "K".^[12]

The English and French speaking countries adopted Davy and Gay-Lussac/Thénard's name Potassium, while the Germanic countries adopted Gilbert/Klaproth's name Kalium.^[13] The "Gold Book" of the International Union of Physical and Applied Chemistry has designated the official chemical symbol as K.^[14]

Properties

Physical

The flame test of potassium.

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. Freshly cut potassium is silvery in appearance, but it begins to tarnish toward gray immediately on exposure to air.^[15] In a flame test, potassium and its compounds emit a lilac color with a peak emission wavelength of 766.5 nanometers.^[16]

Chemical

Neutral potassium atoms have 19 electrons, one more than the extremely stable configuration of the noble gas argon. Because of this and 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 than to gain one and acquire a negative charge (though negatively charged alkalide K⁻
ions are not impossible).^[17][18] This process requires so little energy that potassium is readily oxidized by atmospheric oxygen. In contrast, the second ionization energy is very high (3052 kJ/mol), because removal of two electrons breaks the stable noble gas electronic configuration (the configuration of the inert argon).^[18] Potassium therefore does not form compounds with the oxidation state of +2 or higher.^[17]

Potassium is an extremely active metal that reacts violently with oxygen in water and air. With oxygen it forms potassium peroxide, and with water potassium forms potassium hydroxide. The reaction of potassium with water is dangerous because of its violent exothermic character and the production of hydrogen gas. Hydrogen reacts again with atmospheric oxygen, producing water, which reacts with the remaining potassium. This reaction requires only traces of water; because of this, potassium and the liquid sodium-potassium (NaK) alloy are potent desiccants that can be used to dry solvents prior to distillation.^[19]

Because of the sensitivity of potassium to water and air, reactions with other elements are possible only in an inert atmosphere such as argon gas using air-free techniques. Potassium does not react with most hydrocarbons such as mineral oil or kerosene.^[20] 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. In a pure solution, potassium slowly reacts with ammonia to form KNH
₂, but this reaction is accelerated by minute amounts of transition metal salts.^[21] 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.^[22] For example, the preparation of magnesium by this method employs potassium as the reductant:

MgCl
₂ + 2 K → Mg + 2 KCl

Compounds

Structure of solid potassium superoxide (KO
₂).

The only common oxidation state for potassium is +1. Potassium metal is a powerful reducing agent that is easily oxidized to the monopositive cation, K⁺
. Once oxidized, it is very stable and difficult to reduce back to the metal.^[17]

Potassium oxidizes faster than most metals and often forms oxides containing oxygen-oxygen bonds, as do all alkali metals except lithium. There are three possible oxides of potassium: potassium oxide (K₂O), potassium peroxide (K₂O₂), and potassium superoxide (KO₂);^[23] they contain three different oxygen-based ions: oxide (O²⁻
), peroxide (O²⁻
₂), and superoxide (O⁻
₂). The latter two species, especially the superoxide, are rare and are formed only in reaction of very electropositive metals (Na, K, Rb, Cs, etc.) with oxygen; these species contain oxygen-oxygen bonds.^[21] All potassium-oxygen binary compounds are known to react with water violently, forming potassium hydroxide.

Potassium hydroxide (KOH) is a very strong alkali, and up to 1.21 kg of it can dissolve in a single liter of water.^[24][25] KOH reacts readily with carbon dioxide to produce potassium carbonate, and is used to remove traces of the gas from air.

In general, potassium compounds are highly ionic and, owing to the high hydration energy of the K⁺
ion, have excellent water solubility. The main species in water solution are the aquated complexes [K(H
₂O)
_n]⁺
where n = 6 and 7.^[26] The potassium ion is colorless in water and is very difficult to precipitate; possible precipitation methods include reactions with sodium tetraphenylborate, hexachloroplatinic acid, and sodium cobaltinitrite into potassium tetraphenylborate, potassium hexachloroplatinate, and potassium cobaltinitrite.^[20]

Isotopes

Main article: Isotopes of potassium

There are 24 known isotopes of potassium, three of which occur naturally: ³⁹
K (93.3%), ⁴⁰
K (0.0117%), and ⁴¹
K (6.7%). Naturally occurring ⁴⁰
K has a half-life of 1.250×10⁹ years. It decays to stable ⁴⁰
Ar by electron capture or positron emission (11.2%) or to stable ⁴⁰
Ca by beta decay (88.8%).^[27] The decay of ⁴⁰
K to ⁴⁰
Ar 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 (⁴⁰
Ar) was quantitatively retained. Minerals are dated by measurement of the concentration of potassium and the amount of radiogenic ⁴⁰
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.^[27][28] Apart from dating, potassium isotopes have been used as tracers in studies of weathering and for nutrient cycling studies because potassium is a macronutrient required for life.^[29]

⁴⁰
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. ⁴⁰
K is the radioisotope with the largest abundance in the body. In healthy animals and people, ⁴⁰
K represents the largest source of radioactivity, greater even than ¹⁴
C. In a human body of 70 kg mass, about 4,400 nuclei of ⁴⁰
K decay per second.^[30] The activity of natural potassium is 31 Bq/g.^[31]

Cosmic formation and distribution

Potassium in feldspar

Potassium is formed in supernovae by nucleosynthesis from lighter atoms. Potassium is principally created in Type II supernovae via an explosive oxygen-burning process.^[32]40
K is also formed in s-process nucleosynthesis and the neon burning process.^[33]

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.^[34] The potassium concentration in seawater is 0.39 g/L^[5] (0.039 wt/v%), about one twenty-seventh the concentration of sodium.^[35][36]

Potash

Main article: Potash

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, it was not understood for most of its history to be a fundamentally different substance from sodium mineral salts. Georg Ernst Stahl obtained experimental evidence that led him to suggest the fundamental difference of sodium and potassium salts in 1702,^[7] and Henri Louis Duhamel du Monceau was able to prove this difference in 1736.^[37] 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 the alkali in his list of chemical elements in 1789.^[38][39] For a long time the only significant applications for potash were the production of glass, bleach, soap and gunpowder as potassium nitrate.^[40] 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.^[8] The discovery by Justus Liebig in 1840 that potassium is a necessary element for plants and that most types of soil lack potassium^[41] 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.^[42][43][44] Other potash deposits were discovered, and by the 1960s Canada became the dominant producer.^[45][46]

Metal

Humphry Davy

Pieces of potassium metal

Potassium metal was first isolated in 1807 by Sir Humphry Davy, who derived it from caustic potash (KOH, potassium hydroxide) by electrolysis of molten KOH with the newly discovered voltaic pile. Potassium was the first metal that was isolated by electrolysis.^[47] Later in the same year, Davy reported extraction of the metal sodium from a mineral derivative (caustic soda, NaOH, or lye) rather than a plant salt, by a similar technique, demonstrating that the elements, and thus the salts, are different.^{[38][39][48][49]} 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.^[39]

Geology

Elemental potassium does not occur in nature because of its high reactivity. It reacts violently with water (see section Precautions below)^[20] 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
₂·6(H
₂O)), kainite (MgSO
₄·KCl·3H
₂O) and langbeinite (MgSO
₄·K
₂SO
₄) are 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.^[36] 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.^[50]

Biological role

Main article: Potassium in biology

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.^[51] 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).^[52] Potassium ions are present in a wide variety of proteins and enzymes.^[53]

Biochemical function

Potassium levels influence multiple physiological processes, including^[54][55][56]

• resting cellular-membrane potential and the propagation of action potentials in neuronal, muscular, and cardiac tissue. Due to the electrostatic and chemical properties, K⁺
  ions are larger than Na⁺
  ions, and ion channels and pumps in cell membranes can differentiate between the two ions, actively pumping or passively passing one of the two ions while blocking the other.^[57]
  


• hormone secretion and action


• vascular tone


• systemic blood pressure control


• gastrointestinal motility


• acid–base homeostasis


• glucose and insulin metabolism


• mineralocorticoid action


• renal concentrating ability


• fluid and electrolyte balance

Homeostasis

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 levels

Plasma potassium is normally kept at 3.5 to 5.0 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,^[58] and some cardiac, kidney,^[59] and lung diseases progress more rapidly if serum potassium levels are not maintained within the normal range.

An average meal of 40-50 mmol presents the body with more potassium than is present in all plasma (20-25 mmol). However, this surge causes the plasma potassium to rise only 10% at most as a result of prompt and efficient clearance by both renal and extra-renal mechanisms.^[60]

Hypokalemia, a deficiency of potassium in the plasma, can be fatal if severe. Common causes are increased gastrintestinal loss (vomiting, diarrhea), and increased renal loss (diuresis).^[61] Deficiency symptoms include muscle weakness, paralytic ileus, ECG abnormalities, decreased reflex response; and in severe cases, respiratory paralysis, alkalosis, and cardiac arrhythmia.^[62]

Control mechanisms

Potassium content in the plasma is tightly controlled by four basic mechanisms, which have various names and classifications. The four are 1) a reactive negative-feedback system, 2) a reactive feed-forward system, 3) a predictive or circadian system, and 4) an internal or cell membrane transport system. Collectively, the first three are sometimes termed the "external potassium homeostasis system";^{[citation needed]} and the first two, the "reactive potassium homeostasis system".

• The reactive negative-feedback system refers to the system that induces renal secretion of potassium in response to a rise in the plasma potassium (potassium ingestion, shift out of cells, or intravenous infusion.)


• The reactive feed-forward system refers to an incompletely understood system that induces renal potassium secretion in response to potassium ingestion prior to any rise in the plasma potassium. This is probably initiated by gut cell potassium receptors that detect ingested potassium and trigger vagal afferent signals to the pituitary gland.


• The predictive or circadian system increases renal secretion of potassium during mealtime hours (e.g. daytime for humans, nighttime for rodents) independent of the presence, amount, or absence of potassium ingestion. It is mediated by a circadian oscillator in the suprachiasmatic nucleus of the brain (central clock), which causes the kidney (peripheral clock) to secrete potassium in this rhythmic circadian fashion.
  
  

  
  

  The action of the sodium-potassium pump is an example of primary active transport. The two carrier proteins embedded in the cell membrane on the left are using ATP to move sodium out of the cell against the concentration gradient; The two proteins on the right are using secondary active transport to move potassium into the cell: this process results in reconstitution of ATP.

  
  
  
  


• The ion transport system moves potassium across the cell membrane using two mechanisms. One is active and pumps sodium out of, and potassium into, the cell. The other is passive and allows potassium to leak out of the cell. Potassium and sodium cations influence fluid distribution between intracellular and extracellular compartments by osmotic forces. The movement of potassium and sodium through the cell membrane is mediated by the Na+/K+-ATPase pump.^[63] This ion pump uses ATP to pump three sodium ions out of the cell and two potassium ions into the cell, creating an electrochemical gradient and electromotive force across the cell membrane. The highly selective potassium ion channels (which are tetramers) are crucial for hyperpolarization inside neurons after an action potential is triggered, to cite one example. The most recently discovered potassium ion channel is KirBac3.1, which makes a total of five potassium ion channels (KcsA, KirBac1.1, KirBac3.1, KvAP, and MthK) with a determined structure. All five are from prokaryotic species.^[64]
  

Renal filtration, reabsorption, and excretion

Renal handling of potassium is closely connected to sodium handling. Potassium is the major cation (positive ion) inside animal cells [150 mmol/L, (4.8 g)], while sodium is the major cation of extracellular fluid [150 mmol/L, (3.345 g)]. In the kidneys, about 180 liters of plasma is filtered through the glomeruli and into the renal tubules per day.^[65] This filtering involves about 600 g of sodium and 33 g of potassium. Since only 1–10 g of sodium and 1–4 g of potassium are likely to be replaced by diet, renal filtering must efficiently reabsorb the remainder from the plasma.

Sodium is reabsorbed to maintain extracellular volume, osmotic pressure, and serum sodium concentration within narrow limits; potassium is reabsorbed to maintain serum potassium concentration within narrow limits.^[66]Sodium pumps in the renal tubules operate to reabsorb sodium. Potassium must be conserved also, but, because the amount of potassium in the blood plasma is very small and the pool of potassium in the cells is about thirty times as large, the situation is not so critical for potassium. Since potassium is moved passively^[67][68] in counter flow to sodium in response to an apparent (but not actual) Donnan equilibrium,^[69] the urine can never sink below the concentration of potassium in serum except sometimes by actively excreting water at the end of the processing. Potassium is excreted twice and reabsorbed three times before the urine reaches the collecting tubules.^[70] At that point, urine usually has about the same potassium concentration as plasma. At the end of the processing, potassium is secreted one more time if the serum levels are too high.^{[citation needed]}

With no potassium intake, it is excreted at about 200 mg per day until, in about a week, potassium in the serum declines to a mildly deficient level of 3.0–3.5 mmol/L.^[71] If potassium is still withheld, the concentration continues to fall until a severe deficiency causes eventual death.^[72]

The potassium moves passively through pores in the cell membrane. When ions move through pumps there is a gate in the pumps on either side of the cell membrane and only one gate can be open at once. As a result, approximately 100 ions are forced through per second. Pores have only one gate, and there only one kind of ion can stream through, at 10 million to 100 million ions per second.^[73] The pores require calcium to open^[74] although it is thought that the calcium works in reverse by blocking at least one of the pores.^[75] Carbonyl groups inside the pore on the amino acids mimic the water hydration that takes place in water solution^[76] by the nature of the electrostatic charges on four carbonyl groups inside the pore.^[77]

Nutrition

Dietary recommendations

The U.S. Institute of Medicine (IOM) sets Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs), or Adequate Intakes (AIs) for when there is not sufficient information to set EARs and RDAs. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes. The AIs for potassium are: 400 mg of potassium for 0-6-month-old males, 700 mg of potassium for 7-12-month-old males, 3,000 mg of potassium for 1-3-year-old males, 3,800 mg of potassium for 4-8-year-old males, 4,500 mg of potassium for 9-13-year-old males, and 4,700 mg of potassium for males that are 14 years old and older.
The AIs for potassium are: 400 mg of potassium for 0-6-month-old females, 700 mg of potassium for 7-12-month-old females, 3,000 mg of potassium for 1-3-year-old females, 3,800 mg of potassium for 4-8-year-old females, 4,500 mg of potassium for 9-13-year-old females, and 4,700 mg of potassium for females that are 14 years old and older.
The AIs for potassium are: 4,700 mg of potassium for 14-50-year-old pregnant females; furthermore, 5,100 mg of potassium for 14-50-year-old lactating females. As for safety, the IOM also sets Tolerable upper intake levels (ULs) for vitamins and minerals, but for potassium the evidence was insufficient, so no UL established.^[78]

Most Americans consume only half that amount per day.^[79]

Likewise, in the European Union, in particular in Germany and Italy, insufficient potassium intake is somewhat common.^[80] However, the British National Health Service recommends a lower intake, saying that adults need 3,500 mg per day and that excess amounts may cause health problems such as stomach pain and diarrhoea.^[81]

Food sources

Potassium is present in all fruits, vegetables, meat and fish. Foods with high potassium concentrations include yam, parsley, dried apricots, milk, chocolate, all nuts (especially almonds and pistachios), potatoes, bamboo shoots, bananas, avocados, coconut water, soybeans, and bran.^[82]

The USDA lists tomato paste, orange juice, beet greens, white beans, potatoes, plantains, bananas, apricots, and many other dietary sources of potassium, ranked in descending order according to potassium content. A day's worth of potassium is in 5 plantains or 11 bananas.^[83]

Deficient intake

Diets low in potassium can lead to hypertension^[84] and hypokalemia.

Supplementation

Supplements of potassium are most widely used in conjunction with diuretics that block reabsorption of sodium and water upstream from the distal tubule (thiazides and loop diuretics), because this promotes increased distal tubular potassium secretion, with resultant increased potassium excretion. A variety of prescription and over-the counter supplements are available. Potassium chloride may be dissolved in water, but the salty/bitter taste make liquid supplements unpalatable.^[85] Typical doses range from 10 mmol (400 mg), to 20 mmol (800 mg). Potassium is also available in tablets or capsules, which are formulated to allow potassium to leach slowly out of a matrix, since very high concentrations of potassium ion that occur adjacent to a solid tablet can injure the gastric or intestinal mucosa. For this reason, non-prescription potassium pills are limited by law in the US to a maximum of 99 mg of potassium.^{[citation needed]}

Since the kidneys are the site of potassium excretion, individuals with impaired kidney function are at risk for hyperkalemia if dietary potassium and supplements are not restricted. The more severe the impairment, the more severe is the restriction necessary to avoid hyperkalemia.^{[citation needed]}

A meta-analysis concluded that a 1640 mg increase in the daily intake of potassium was associated with a 21% lower risk of stroke.^[86]Potassium chloride and potassium bicarbonate may be useful to control mild hypertension.^[87]

Detection by taste buds

Potassium can be detected by taste because it triggers three of the five types of taste sensations, according to concentration. Dilute solutions of potassium ions taste sweet, allowing moderate concentrations in milk and juices, while higher concentrations become increasingly bitter/alkaline, and finally also salty to the taste. The combined bitterness and saltiness of high-potassium solutions makes high-dose potassium supplementation by liquid drinks a palatability challenge.^[85][88]

Commercial production

Mining

Sylvite from New Mexico

Potassium salts such as carnallite, langbeinite, polyhalite, and sylvite form extensive evaporite deposits in ancient lake bottoms and seabeds,^[35] making extraction of potassium salts in these environments commercially viable. The principal source of potassium – potash – is mined in Canada, Russia, Belarus, Kazakhstan, Germany, Israel, United States, Jordan, and other places around the world.^[89][90][91] 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 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 is the Potash Corporation of Saskatchewan.^[92] The water of 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.^[90][91]

Monte Kali, a potash mining and beneficiation waste heap in Hesse, Germany, consisting mostly of sodium chloride.

Chemical extraction

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 at different temperatures. Electrostatic separation of the ground salt mixture 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.^[36]

Pure potassium metal can be isolated by electrolysis of its hydroxide in a process that has changed little since it 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 the reaction of potassium fluoride with calcium carbide was also used to produce potassium.^[36][93]

Na + KCl → NaCl + K                      (Thermal method)

2 KF + CaC
₂ → 2 K + CaF
₂ + 2 C    (Griesheimer process)

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 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.^[94][95]

Commercial uses

Fertilizer

Potassium sulfate/magnesium sulfate fertilizer

Potassium ions are an essential component of plant nutrition and are found in most soil types.^[8] They are used as a fertilizer in agriculture, horticulture, and hydroponic culture in the form of chloride (KCl), sulfate (K
₂SO
₄), or nitrate (KNO
₃). Agricultural fertilizers consume 95% of global potassium chemical production, and about 90% of this potassium is supplied as KCl.^[8] The potassium content of most plants range from 0.5% to 2% of the harvested weight of crops, conventionally expressed as amount of K
₂O. 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 is produced mostly by decomposition of the complex minerals kainite (MgSO
₄·KCl·3H
₂O) and langbeinite (MgSO
₄·K
₂SO
₄). Only a very few fertilizers contain potassium nitrate.^[96] In 2005, about 93% of world potassium production was consumed by the fertilizer industry.^[91]

Medical use

See also: Potassium chloride (medical use)

Potassium, in the form of potassium chloride is used as a medication to treat and prevent low blood potassium.^[97] Low blood potassium may occur due to vomiting, diarrhea, or certain medications.^[98] It is given by slow injection into a vein or by mouth.^[99]

Food additives

Potassium sodium tartrate (KNaC
₄H
₄O
₆, Rochelle salt) is the main constituent 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 the tanning of leathers.^[100][101]

Industrial

Major potassium chemicals are potassium hydroxide, potassium carbonate, potassium sulfate, and potassium chloride. Megatons of these compounds are produced annually.^[102]

Potassium hydroxide 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.^[103][104]

Potassium nitrate (KNO
₃) or saltpeter 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 is also used in organic synthesis to make nitriles. Potassium carbonate (K
₂CO
₃ or potash) is used in the manufacture of glass, soap, color TV tubes, fluorescent lamps, textile dyes and pigments.^[105] 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) was formerly used as a sedative and in photography.^[8]

Potassium chromate (K
₂CrO
₄) is used in inks, dyes, stains (bright yellowish-red color); in explosives and fireworks; in the tanning of leather, in fly paper and safety matches,^[106] but all these uses are due to the chemistry of the chromate ion, rather than the potassium ion.^[107]

Niche uses

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.^[108][109]

4 KO
₂ + 2 CO₂ → 2 K
₂CO
₃ + 3 O
₂

Another example is potassium cobaltinitrite, K
₃[Co(NO
₂)
₆], which is used as artist's pigment under the name of Aureolin or Cobalt Yellow.^[110]

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 ⁴⁰K is one of only two stable fermions amongst the alkali metals.^[111]

Laboratory uses

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.^[112] The ternary alloy of 12% Na, 47% K and 41% Cs has the lowest melting point of −78 °C of any metallic compound.^[15]

Metallic potassium is used in several types of magnetometers.^[113]

Precautions

Potassium

Hazards
GHS pictograms
GHS signal word	Danger
GHS hazard statements	H260, H314
GHS precautionary statements	P223, P231+232, P280, P305+351+338, P370+378, P422[114]
NFPA 704	3 3 2 W

Play media

A reaction of potassium metal with water. Hydrogen is produced, and with potassium vapor, burns with a pink or lilac flame. Strongly alkaline potassium hydroxide is formed in solution.

Potassium metal reacts violently with water producing potassium hydroxide (KOH) and hydrogen gas.

2 K (s) + 2  H₂O (l) → 2 KOH (aq) + H
₂↑ (g)

This reaction is exothermic and releases enough heat to ignite the resulting hydrogen in the presence of oxygen. Potassium tends to explode in contact with water and without the the oxygen presence. It is called coulombic explosion, possibly splashing onlookers with potassium hydroxide, which is a strong alkali that destroys living tissue and causes skin burns. Finely grated potassium ignites in air at room temperature. The bulk metal ignites in air if heated. Because its density is 0.89 g/cm³, burning potassium floats in water that exposes it to atmospheric oxygen. Many common fire extinguishing agents, including water, either are ineffective or make a potassium fire worse. Nitrogen, argon, sodium chloride (table salt), sodium carbonate (soda ash), and silicon dioxide (sand) are effective if they are dry. Some Class D dry powder extinguishers designed for metal fires are also effective. These agents deprive the fire of oxygen and cool the potassium metal.^[115]

Potassium reacts violently with halogens and detonates in the presence of bromine. It also reacts explosively with sulfuric acid. During combustion, potassium forms peroxides and superoxides. These peroxides may react violently with organic compounds such as oils. Both peroxides and superoxides may react explosively with metallic potassium.^[116]

Because potassium reacts with water vapor in the air, it is usually stored under anhydrous mineral oil or kerosene. Unlike lithium and sodium, however, potassium should not be stored under oil for longer than six months, unless in an inert (oxygen free) atmosphere, or under vacuum. After prolonged storage in air dangerous shock-sensitive peroxides can form on the metal and under the lid of the container, and can detonate upon opening.^[117]

Because of the highly reactive nature of potassium metal, it must be handled with great care, with full skin and eye protection and preferably an explosion-resistant barrier between the user and the metal. Ingestion of large amounts of potassium compounds can lead to hyperkalemia, strongly influencing the cardiovascular system.^[118][119] Potassium chloride is used in the United States for lethal injection executions.^[118]

See also

Books View or order collections of articles	Potassium Period 4 elements Alkali metals Chemical elements (sorted alphabetically) Chemical elements (sorted by number)
Portals Access related topics	Chemistry portal Medicine portal
Find out more on Wikipedia's Sister projects	Media from Commons Definitions from Wiktionary Textbooks from Wikibooks Learning resources from Wikiversity

References

1. 
   ^ Meija, J.; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
   


2. 
   ^ Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.122. ISBN 1439855110.
   


3. 
   ^ Magnetic susceptibility of the elements and inorganic compounds, in Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
   


4. 
   ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
   


5. 
   ^ ^ab Webb, D. A. (April 1939). "The Sodium and Potassium Content of Sea Water" (PDF). The Journal of Experimental Biology (2): 183.
   


6. 
   ^ Anthoni, J. (2006). "Detailed composition of seawater at 3.5% salinity". seafriends.org.nz. Retrieved 2011-09-23.
   


7. 
   ^ ^ab Marggraf, Andreas Siegmund (1761). Chymische Schriften. p. 167.
   


8. 
   ^ ^abcde Greenwood, p. 73
   


9. 
   ^ Davy, Humphry (1808). "On some new phenomena of chemical changes produced by electricity, in particular the decomposition of the fixed alkalies, and the exhibition of the new substances that constitute their bases; and on the general nature of alkaline bodies". Philosophical Transactions of the Royal Society. 98: 32. doi:10.1098/rstl.1808.0001.
   


10. 
    ^ M. Klaproth (1797) "Nouvelles données relatives à l'histoire naturelle de l'alcali végétal" (New data regarding the natural history of the vegetable alkali), Mémoires de l'Académie royale des sciences et belles-lettres (Berlin), pp. 9-13 ; see p. 13. From p. 13: "Cet alcali ne pouvant donc plus être envisagé comme un produit de la végétation dans les plantes, occupe une place propre dans la série des substances primitivement simples du règne minéral, &I il devient nécessaire de lui assigner un nom, qui convienne mieux à sa nature.
    
    La dénomination de Potasche (potasse) que la nouvelle nomenclature françoise a consacrée comme nom de tout le genre, ne sauroit faire fortune auprès des chimistes allemands, qui sentent à quel point la dérivation étymologique en est vicieuse. Elle est prise en effet de ce qu'anciennement on se servoit pour la calcination des lessives concentrées des cendres, de pots de fer (pott en dialecte de la Basse-Saxe) auxquels on a substitué depuis des fours à calciner.
    
    Je propose donc ici, de substituer aux mots usités jusqu'ici d'alcali des plantes, alcali végétal, potasse, &c. celui de kali, & de revenir à l'ancienne dénomination de natron, au lieu de dire alcali minéral, soude &c."
    
    (This alkali [i.e., potash] — [which] therefore can no longer be viewed as a product of growth in plants — occupies a proper place in the originally simple series of the mineral realm, and it becomes necessary to assign it a name that is better suited to its nature.
    
    The name of "potash" (potasse), which the new French nomenclature has bestowed as the name of the entire species [i.e., substance], would not find acceptance among German chemists, who feel to some extent [that] the etymological derivation of it is faulty. Indeed, it is taken from [the vessels] that one formerly used for the roasting of washing powder concentrated from cinders: iron pots (pott in the dialect of Lower Saxony), for which roasting ovens have been substituted since then.
    
    Thus I now propose to substitute for the until now common words of "plant alkali", "vegetable alkali", "potash", etc., that of kali ; and to return to the old name of natron instead of saying "mineral alkali", "soda", etc.)
    


11. 
    ^ Davy, Humphry (1809). "Ueber einige neue Erscheinungen chemischer Veränderungen, welche durch die Electricität bewirkt werden; insbesondere über die Zersetzung der feuerbeständigen Alkalien, die Darstellung der neuen Körper, welche ihre Basen ausmachen, und die Natur der Alkalien überhaupt" [On some new phenomena of chemical changes that are achieved by electricity; particularly the decomposition of flame-resistant alkalis [i.e., alkalies that cannot be reduced to their base metals by flames], the preparation of new substances that constitute their [metallic] bases, and the nature of alkalies generally]. Annalen der Physik. 31 (2): 113–175. Bibcode:1809AnP....31..113D. doi:10.1002/andp.18090310202. p. 157: In unserer deutschen Nomenclatur würde ich die Namen Kalium und Natronium vorschlagen, wenn man nicht lieber bei den von Herrn Erman gebrauchten und von mehreren angenommenen Benennungen Kali-Metalloid and Natron-Metalloid, bis zur völligen Aufklärung der chemischen Natur dieser räthzelhaften Körper bleiben will. Oder vielleicht findet man es noch zweckmässiger fürs Erste zwei Klassen zu machen, Metalle und Metalloide, und in die letztere Kalium und Natronium zu setzen. — Gilbert. (In our German nomenclature, I would suggest the names Kalium and Natronium, if one would not rather continue with the appellations Kali-metalloid and Natron-metalloid which are used by Mr. Erman [i.e., German physics professor Paul Erman (1764–1851)] and accepted by several [people], until the complete clarification of the chemical nature of these puzzling substances. Or perhaps one finds it yet more advisable for the present to create two classes, metals and metalloids, and to place Kalium and Natronium in the latter — Gilbert.)
    


12. 
    ^ Berzelius, J. Jacob (1814) Försök, att, genom användandet af den electrokemiska theorien och de kemiska proportionerna, grundlägga ett rent vettenskapligt system för mineralogien [Attempt, by the use of electrochemical theory and chemical proportions, to found a pure scientific system for mineralogy]. Stockholm, Sweden: A. Gadelius., p. 87.
    


13. 
    ^ 19. Kalium (Potassium) - Elementymology & Elements Multidict
    


14. 
    ^ IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997)
    


15. 
    ^ ^ab Greenwood, p. 76
    


16. 
    ^ Greenwood, p. 75
    


17. 
    ^ ^abc Dye, J. L. (1979). "Compounds of Alkali Metal Anions". Angewandte Chemie International Edition. 18 (8): 587–598. doi:10.1002/anie.197905871.
    


18. 
    ^ ^ab James, A. M.; Lord, M. P. (1992). Macmillan's chemical and physical data. London: Macmillan. ISBN 0-333-51167-0.
    


19. 
    ^ Burkhardt, p. 35
    


20. 
    ^ ^abc Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). "Potassium". Lehrbuch der Anorganischen Chemie (in German) (91–100 ed.). Walter de Gruyter. ISBN 3-11-007511-3.
    


21. 
    ^ ^ab Burkhardt, p. 32
    


22. 
    ^ Rieke, R. D. (1989). "Preparation of Organometallic Compounds from Highly Reactive Metal Powders". Science. 246 (4935): 1260–4. Bibcode:1989Sci...246.1260R. doi:10.1126/science.246.4935.1260. PMID 17832221.
    


23. 
    ^ Lide, David R. (1998). Handbook of Chemistry and Physics (87th ed.). Boca Raton, Florida, United States: CRC Press. pp. 477, 520. ISBN 0-8493-0594-2.
    


24. 
    ^ Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. p. 4–80. ISBN 0-8493-0486-5.
    


25. 
    ^ Schultz, p. 94
    


26. 
    ^ Lincoln, S. F.; Richens, D. T. and Sykes, A. G. "Metal Aqua Ions" in J. A. McCleverty and T. J. Meyer (eds.) Comprehensive Coordination Chemistry II, Vol. 1, pp. 515–555,
    ISBN 978-0-08-043748-4.
    


27. 
    ^ ^ab Georges, Audi; Bersillon, O.; Blachot, J.; Wapstra, A. H. (2003). "The NUBASE Evaluation of Nuclear and Decay Properties". Nuclear Physics A. Atomic Mass Data Center. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
    


28. 
    ^ Bowen, Robert; Attendorn, H. G. (1988). "Theory and Assumptions in Potassium–Argon Dating". Isotopes in the Earth Sciences. Springer. pp. 203–8. ISBN 978-0-412-53710-3.
    


29. 
    ^ Anaç, D. & Martin-Prével, P. (1999). Improved crop quality by nutrient management. Springer. pp. 290–. ISBN 978-0-7923-5850-3.
    


30. 
    ^ "Radiation and Radioactive Decay. Radioactive Human Body". Harvard Natural Sciences Lecture Demonstrations. Retrieved July 2, 2016.
    


31. 
    ^ Winteringham, F. P. W; Effects, F.A.O. Standing Committee on Radiation, Land And Water Development Division, Food and Agriculture Organization of the United Nations (1989). Radioactive fallout in soils, crops and food: a background review. Food & Agriculture Org. p. 32. ISBN 978-92-5-102877-3.CS1 maint: Multiple names: authors list (link)
    


32. 
    ^ Shimansky, V.; Bikmaev, I. F.; Galeev, A. I.; Shimanskaya, N. N.; et al. (September 2003). "Observational constraints on potassium synthesis during the formation of stars of the Galactic disk". Astronomy Reports. 47 (9): 750–762. Bibcode:2003ARep...47..750S. doi:10.1134/1.1611216.
    


33. 
    ^ The, L.-S.; Eid, M. F. El; Meyer, B. S. (2000). "A New Study of s-Process Nucleosynthesis in Massive Stars". The Astrophysical Journal. 533 (2): 998. doi:10.1086/308677. ISSN 0004-637X.
    


34. 
    ^ Greenwood, p. 69
    


35. 
    ^ ^ab Micale, Giorgio; Cipollina, Andrea; Rizzuti, Lucio (2009). Seawater Desalination: Conventional and Renewable Energy Processes. Springer. p. 3. ISBN 978-3-642-01149-8.
    


36. 
    ^ ^abcd Prud'homme, Michel; Krukowski, Stanley T. (2006). "Potash". Industrial minerals & rocks: commodities, markets, and uses. Society for Mining, Metallurgy, and Exploration. pp. 723–740. ISBN 978-0-87335-233-8.
    


37. 
    ^ du Monceau, H. L. D. (1702–1797). "Sur la Base de Sel Marin". Memoires de l'Academie royale des Sciences (in French): 65–68.
    


38. 
    ^ ^ab Weeks, Mary Elvira (1932). "The discovery of the elements. IX. Three alkali metals: Potassium, sodium, and lithium". Journal of Chemical Education. 9 (6): 1035. Bibcode:1932JChEd...9.1035W. doi:10.1021/ed009p1035.
    


39. 
    ^ ^abc Siegfried, R. (1963). "The Discovery of Potassium and Sodium, and the Problem of the Chemical Elements". Isis. 54 (2): 247–258. doi:10.1086/349704. JSTOR 228541.
    


40. 
    ^ Browne, C. A. (1926). "Historical notes upon the domestic potash industry in early colonial and later times". Journal of Chemical Education. 3 (7): 749–756. Bibcode:1926JChEd...3..749B. doi:10.1021/ed003p749.
    


41. 
    ^ Liebig, Justus von (1840). Die organische Chemie in ihrer Anwendung auf Agricultur und Physiologie (in German).
    


42. 
    ^ Cordel, Oskar (1868). Die Stassfurter Kalisalze in der Landwirthschalt: Eine Besprechung ... (in German). L. Schnock.
    


43. 
    ^ Birnbaum, Karl (1869). Die Kalidüngung in ihren Vortheilen und Gefahren (in German).
    


44. 
    ^ United Nations Industrial Development Organization and Int'l Fertilizer Development Center (1998). Fertilizer Manual. pp. 46, 417. ISBN 978-0-7923-5032-3.
    


45. 
    ^ Miller, H. (1980). "Potash from Wood Ashes: Frontier Technology in Canada and the United States". Technology and Culture. 21 (2): 187–208. doi:10.2307/3103338. JSTOR 3103338.
    


46. 
    ^ Rittenhouse, P. A. (1979). "Potash and politics". Economic Geology. 74 (2): 353–7. doi:10.2113/gsecongeo.74.2.353.
    


47. 
    ^ Enghag, P. (2004). "11. Sodium and Potassium". Encyclopedia of the elements. Wiley-VCH Weinheim. ISBN 3-527-30666-8.
    


48. 
    ^ Davy, Humphry (1808). "On some new phenomena of chemical changes produced by electricity, in particular the decomposition of the fixed alkalies, and the exhibition of the new substances that constitute their bases; and on the general nature of alkaline bodies". Philosophical Transactions of the Royal Society. 98: 1–44. doi:10.1098/rstl.1808.0001.
    


49. 
    ^ Shaposhnik, V. A. (2007). "History of the discovery of potassium and sodium (on the 200th anniversary of the discovery of potassium and sodium)". Journal of Analytical Chemistry. 62 (11): 1100–2. doi:10.1134/S1061934807110160.
    


50. 
    ^ Ross, William H. (1914). "The Origin of Nitrate Deposits". Popular Science. Bonnier Corporation. pp. 134–145.
    


51. 
    ^ Abdel-Wahab, M.; Youssef, S.; Aly, A.; el-Fiki, S.; et al. (1992). "A simple calibration of a whole-body counter for the measurement of total body potassium in humans". International Journal of Radiation Applications and Instrumentation. Part A. Applied Radiation and Isotopes. 43 (10): 1285–9. doi:10.1016/0883-2889(92)90208-V. PMID 1330980.
    


52. 
    ^ Chang, Raymond (2007). Chemistry. McGraw-Hill Higher Education. p. 52. ISBN 978-0-07-110595-8.
    


53. 
    ^ Vašák, Milan; Schnabl, Joachim (2016). "Chapter 8. Sodium and Potassium Ions in Proteins and Enzyme Catalysis". In Astrid, Sigel; Helmut, Sigel; Roland K.O., Sigel. The Alkali Metal Ions: Their Role in Life. Metal Ions in Life Sciences. 16. Springer. pp. 259–290. doi:10.1007/978-4-319-21756-7_8.
    


54. 
    ^ ID, Linus S, Wingo CS. Disorders of potassium metabolism. In: Freehally J, Johnson RJ, Floege J, eds. Comprehensive clinical nephrology. 5th ed.St. Louis: Saunders, 2014:118-118
    


55. 
    ^ Malnic G, Giebisch G, Muto S, Wang W, Bailey MA, Satlin LM. Regulation of K+ excretion. In: Alpern RJ, Caplan MJ, Moe OW, eds. Seldin and Giebisch’s the kidney: physiology and pathophysiology. 5th ed. London: Academic Press, 2013:1659-1716
    


56. 
    ^ Mount DB, Zandi-Nejad K. Disorders of potassium balance. In: Taal MW, Chertow GM, Marsden PA, Skorecki KL, Yu ASL, Brenner BM, eds. The kidney. 9th ed. Philadelphia: Elsevier, 2012:640-688
    


57. 
    ^ Lockless, S. W.; Zhou, M.; MacKinnon, R. (2007). "Structural and thermodynamic properties of selective ion binding in a K+ channel". PLoS Biol. 5 (5): e121. doi:10.1371/journal.pbio.0050121. PMC 1858713. PMID 17472437.
    


58. 
    ^ Goyal, Abhinav; Spertus, John A.; Gosch, Kensey; Venkitachalam, Lakshmi; Jones, Philip G.; Van den Berghe, Greet; Kosiborod, Mikhail (2012). "Serum Potassium Levels and Mortality in Acute Myocardial Infarction". JAMA. 307 (2): 157–164. doi:10.1001/jama.2011.1967.
    


59. 
    ^ Smyth, A.; Dunkler, D.; Gao, P.; et al. (2014). "The relationship between estimated sodium and potassium excretion and subsequent renal outcomes". Kidney Int. 86 (6): 1205–1212. doi:10.1038/ki.2014.214.
    


60. 
    ^ Moore-Ede, M. C. (1986). "Physiology of the circadian timing system: predictive versus reactive homeostasis". Am J Physiol. 250: R737–R752.
    


61. 
    ^ Slonim, Anthony D.; Pollack, Murray M. (2006). "Potassium". Pediatric critical care medicine. Lippincott Williams & Wilkins. p. 812. ISBN 978-0-7817-9469-5.
    


62. 
    ^ Visveswaran, Kasi (2009). "hypokalemia". Essentials of Nephrology (2nd ed.). BI Publications. p. 257. ISBN 978-81-7225-323-3.
    


63. 
    ^ Campbell, Neil (1987). Biology. Menlo Park, California: Benjamin/Cummings Pub. Co. p. 795. ISBN 0-8053-1840-2.
    


64. 
    ^ Hellgren, Mikko; Sandberg, Lars; Edholm, Olle (2006). "A comparison between two prokaryotic potassium channels (K_irBac1.1 and KcsA) in a molecular dynamics (MD) simulation study". Biophysical Chemistry. 120 (1): 1–9. doi:10.1016/j.bpc.2005.10.002. PMID 16253415.
    


65. 
    ^ Potts, W. T. W.; Parry, G. (1964). Osmotic and ionic regulation in animals. Pergamon Press.
    


66. 
    ^ Lans, H. S.; Stein, I. F.; Meyer, K. A. (1952). "The relation of serum potassium to erythrocyte potassium in normal subjects and patients with potassium deficiency". American Journal of the Medical Sciences. 223 (1): 65–74. doi:10.1097/00000441-195201000-00011. PMID 14902792.
    


67. 
    ^ Bennett, C. M.; Brenner, B. M.; Berliner, R. W. (1968). "Micropuncture study of nephron function in the rhesus monkey". Journal of Clinical Investigation. 47 (1): 203–216. doi:10.1172/JCI105710. PMC 297160. PMID 16695942.
    


68. 
    ^ Solomon, A. K. (1962). "Pumps in the living cell". Scientific American. 207 (2): 100–8. Bibcode:1962SciAm.207b.100S. doi:10.1038/scientificamerican0862-100. PMID 13914986.
    


69. 
    ^ Kernan, Roderick P. (1980). Cell potassium (Transport in the life sciences). New York: Wiley. pp. 40, 48. ISBN 0-471-04806-2.
    


70. 
    ^ Wright, F. S. (1977). "Sites and mechanisms of potassium transport along the renal tubule". Kidney International. 11 (6): 415–432. doi:10.1038/ki.1977.60. PMID 875263.
    


71. 
    ^ Squires, R. D.; Huth, E. J. (1959). "Experimental potassium depletion in normal human subjects. I. Relation of ionic intakes to the renal conservation of potassium". Journal of Clinical Investigation. 38 (7): 1134–48. doi:10.1172/JCI103890. PMC 293261. PMID 13664789.
    


72. 
    ^ Fiebach, Nicholas H.; Barker, Lee Randol; Burton, John Russell & Zieve, Philip D. (2007). Principles of ambulatory medicine. Lippincott Williams & Wilkins. pp. 748–750. ISBN 978-0-7817-6227-4.
    


73. 
    ^ Gadsby, D. C. (2004). "Ion transport: spot the difference". Nature. 427 (6977): 795–7. Bibcode:2004Natur.427..795G. doi:10.1038/427795a. PMID 14985745.; for a diagram of the potassium pores are viewed, see Miller, C (2001). "See potassium run". Nature. 414 (6859): 23–24. Bibcode:2001Natur.414...23M. doi:10.1038/35102126. PMID 11689922.
    


74. 
    ^ Jiang, Y.; Lee, A.; Chen, J.; Cadene, M.; et al. (2002). "Crystal structure and mechanism of a calcium-gated potassium channel" (PDF). Nature. 417 (6888): 515–22. Bibcode:2002Natur.417..515J. doi:10.1038/417515a. PMID 12037559. Archived from the original on 2009-04-24.CS1 maint: BOT: original-url status unknown (link)
    


75. 
    ^ Shi, N.; Ye, S.; Alam, A.; Chen, L.; et al. (2006). "Atomic structure of a Na⁺- and K⁺-conducting channel". Nature. 440 (7083): 570–4. Bibcode:2006Natur.440..570S. doi:10.1038/nature04508. PMID 16467789.; includes a detailed picture of atoms in the pump.
    


76. 
    ^ Zhou, Y.; Morais-Cabral, J. H.; Kaufman, A.; MacKinnon, R. (2001). "Chemistry of ion coordination and hydration revealed by a K⁺ channel-Fab complex at 2.0 A resolution". Nature. 414 (6859): 43–48. Bibcode:2001Natur.414...43Z. doi:10.1038/35102009. PMID 11689936.
    


77. 
    ^ Noskov, S. Y.; Bernèche, S.; Roux, B. (2004). "Control of ion selectivity in potassium channels by electrostatic and dynamic properties of carbonyl ligands". Nature. 431 (7010): 830–4. Bibcode:2004Natur.431..830N. doi:10.1038/nature02943. PMID 15483608.
    


78. 
    ^ Potassium. IN: Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. National Academy Press. 2005, PP.186-268.
    


79. 
    ^ Panel on Dietary Reference Intakes for Electrolytes and Water, Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition (2004). DRI, dietary reference intakes for water, potassium, sodium, chloride, and sulfate. Washington, D.C.: National Academies Press. ISBN 0-309-53049-0. Archived from the original on 2011-10-06.CS1 maint: Multiple names: authors list (link)
    


80. 
    ^ Karger, S. (2004). "Energy and nutrient intake in the European Union". Annals of Nutrition and Metabolism. 48 (2 (suppl)): 1–16. doi:10.1159/000083041.
    


81. 
    ^ https://www.nhs.uk/conditions/vitamins-and-minerals/others/#potassium NHS Choices - Other vitamins and minerals - Potassium
    


82. 
    ^ "Potassium Food Charts". Asia Pacific Journal of Clinical Nutrition. Retrieved 2011-05-18.
    


83. 
    ^ "Potassium Content of Selected Foods per Common Measure, sorted by nutrient content" (PDF). USDA National Nutrient Database for Standard Reference, Release 20. Archived from the original (PDF) on December 17, 2008.
    


84. 
    ^ Whelton PK, He J, Cutler JA, Brancati FL, Appel LJ, Follmann D, Klag MJ (1997). "Effects of oral potassium on blood pressure. Meta-analysis of randomized controlled clinical trials". JAMA. 277 (20): 1624–32. doi:10.1001/jama.1997.03540440058033. PMID 9168293.CS1 maint: Uses authors parameter (link)
    


85. 
    ^ ^ab Institute of Medicine (U.S.). Committee on Optimization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situations; Institute of Medicine (U.S.). Committee on Military Nutrition Research (2006). Nutrient composition of rations for short-term, high-intensity combat operations. National Academies Press. pp. 287–. ISBN 978-0-309-09641-6.
    


86. 
    ^ D'Elia, L.; Barba, G.; Cappuccio, F.; Strazzullo (2011). "Potassium Intake, Stroke, and Cardiovascular Disease: A Meta-Analysis of Prospective Studies". J Am Coll Cardiol. 57 (10): 1210–9. doi:10.1016/j.jacc.2010.09.070. PMID 21371638.
    


87. 
    ^ He FJ, Marciniak M, Carney C, Markandu ND, Anand V, Fraser WD, Dalton RN, Kaski JC, MacGregor GA (2010). "Effects of potassium chloride and potassium bicarbonate on endothelial function, cardiovascular risk factors, and bone turnover in mild hypertensives". Hypertension. 55 (3): 681–8. doi:10.1161/HYPERTENSIONAHA.109.147488. PMID 20083724.
    


88. 
    ^ Shallenberger, R. S. (1993). Taste chemistry. Springer. pp. 120–. ISBN 978-0-7514-0150-9.
    


89. 
    ^ Garrett, Donald E. (1995-12-31). Potash: deposits, processing, properties and uses. Springer. ISBN 978-0-412-99071-7.
    


90. 
    ^ ^ab Ober, Joyce A. "Mineral Commodity Summaries 2008:Potash" (PDF). United States Geological Survey. Retrieved 2008-11-20.
    


91. 
    ^ ^abc Ober, Joyce A. "Mineral Yearbook 2006:Potash" (PDF). United States Geological Survey. Retrieved 2008-11-20.
    


92. 
    ^ Wishart, David J. (2004). Encyclopedia of the Great Plains. U of Nebraska Press. p. 433. ISBN 978-0-8032-4787-1.
    


93. 
    ^ Chiu, Kuen-Wai (2000). Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc. doi:10.1002/0471238961.1615200103080921.a01.pub2. ISBN 9780471238966.
    


94. 
    ^ Burkhardt, p. 34
    


95. 
    ^ Delahunt, J.; Lindeman, T. (2007). "Review of the safety of potassium and potassium oxides, including deactivation by introduction into water". Journal of Chemical Health and Safety. 14 (2): 21–32. doi:10.1016/j.jchas.2006.09.010.
    


96. 
    ^ Roy, Amit H. (2007). Kent and Riegel's handbook of industrial chemistry and biotechnology. Springer. pp. 1135–57. ISBN 978-0-387-27843-8.
    


97. 
    ^ WHO Model Formulary 2008 (PDF). World Health Organization. 2009. p. 491. ISBN 9789241547659. Archived (PDF) from the original on 13 December 2016. Retrieved 8 January 2017.
    


98. 
    ^ "Potassium chloride medical facts from Drugs.com". www.drugs.com. Archived from the original on 18 January 2017. Retrieved 14 January 2017.
    


99. 
    ^ British national formulary : BNF 69 (69 ed.). British Medical Association. 2015. p. 680, 684. ISBN 9780857111562.
    


100. 
     ^ Figoni, Paula I (2010). "Bleaching and Maturing Agents". How Baking Works: Exploring the Fundamentals of Baking Science. John Wiley and Sons. p. 86. ISBN 978-0-470-39267-6.
     


101. 
     ^ Chichester, C. O. (July 1986). "Uses and Exposure to Sulfites in Food". Advances in food research. Academic Press. pp. 4–6. ISBN 978-0-12-016430-1.
     


102. 
     ^ Schultz
     


103. 
     ^ Toedt, John; Koza, Darrell & Cleef-Toedt, Kathleen Van (2005). "Personal Cleansing Products: Bar Soap". Chemical composition of everyday products. Greenwood Publishing Group. ISBN 978-0-313-32579-3.
     


104. 
     ^ Schultz, p. 95
     


105. 
     ^ Schultz, p. 99
     


106. 
     ^ Siegel, Richard S. (1940). "Ignition of the safety match". Journal of Chemical Education. 17 (11): 515. Bibcode:1940JChEd..17..515S. doi:10.1021/ed017p515.
     


107. 
     ^ Anger, Gerd; Halstenberg, Jost; Hochgeschwender, Klaus; Scherhag, Christoph; Korallus, Ulrich; Knopf, Herbert; Schmidt, Peter; Ohlinger, Manfred, "Chromium Compounds", Ullmann's Encyclopedia of Industrial Chemistry, 9, Weinheim: Wiley-VCH, p. 178, doi:10.1002/14356007.a07_067
     


108. 
     ^ Greenwood, p. 74
     


109. 
     ^ Marx, Robert F. (1990). The history of underwater exploration. Courier Dover Publications. p. 93. ISBN 978-0-486-26487-5.
     


110. 
     ^ Gettens, Rutherford John & Stout, George Leslie (1966). Painting materials: A short encyclopaedia. Courier Dover Publications. pp. 109–110. ISBN 978-0-486-21597-6.
     


111. 
     ^ Modugno, G.; Benkő, C.; Hannaford, P.; Roati, G.; Inguscio, M. (1999-11-01). "Sub-Doppler laser cooling of fermionic ${}^{40}mathrm{K}$ atoms". Physical Review A. 60 (5): R3373–R3376. arXiv:cond-mat/9908102. Bibcode:1999PhRvA..60.3373M. doi:10.1103/PhysRevA.60.R3373.
     


112. 
     ^ Jackson, C. B.; Werner, R. C. (1957). "Ch. 18: The Manufacture of Potassium and NaK". Handling and uses of the alkali metals. Advances in Chemistry. 19. pp. 169–173. doi:10.1021/ba-1957-0019.ch018. ISBN 978-0-8412-0020-3.
     


113. 
     ^ Kearey, Philip; Brooks, M & Hill, Ian (2002). "Optical Pumped Magnetometer". An introduction to geophysical exploration. Wiley-Blackwell. p. 164. ISBN 978-0-632-04929-5.
     


114. 
     ^ https://www.sigmaaldrich.com/catalog/product/aldrich/244856?lang=en&region=US
     


115. 
     ^ Solomon, Robert E. (2002). Fire and Life Safety Inspection Manual. Jones & Bartlett Learning. p. 459. ISBN 978-0-87765-472-8.
     


116. 
     ^ "DOE Handbook-Alkali Metals Sodium, Potassium, NaK, and Lithium". Hss.doe.gov. Archived from the original on 2010-09-28. Retrieved 2010-10-16.
     


117. 
     ^ Wray, Thomas K. "Danger: peroxidazable chemicals" (PDF). Environmental Health & Public Safety, North Carolina State University. Archived from the original on 2016-07-29.CS1 maint: BOT: original-url status unknown (link)
     


118. 
     ^ ^ab Schonwald, Seth (2004). "Potassium Chloride and Potassium Permanganate". Medical toxicology. Lippincott Williams & Wilkins. pp. 903–5. ISBN 978-0-7817-2845-4.
     


119. 
     ^ Markovchick, Vincent J. & Pons, Peter T. (2003). Emergency medicine secrets. Elsevier Health Sciences. p. 223. ISBN 978-1-56053-503-4.
     

Bibliography

• 
  Burkhardt, Elizabeth R. (2006). "Potassium and Potassium Alloys". Ullmann's Encyclopedia of Industrial Chemistry. A22. pp. 31–38. doi:10.1002/14356007.a22_031.pub2. ISBN 3-527-30673-0.
  


• 
  Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
  


• 
  Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (2007). "Potassium". Lehrbuch der Anorganischen Chemie (in German) (91–100 ed.). Walter de Gruyter. ISBN 3110177706.
  


• 
  Schultz, H.; et al. (2006). "Potassium compounds". Ullmann's Encyclopedia of Industrial Chemistry. A22. pp. 39–103. doi:10.1002/14356007.a22_031.pub2. ISBN 3-527-30673-0.
  


• 
  National Nutrient Database at USDA Website

External links

• 
  Potassium at The Periodic Table of Videos (University of Nottingham)


• 
  Potassium (K) at Encyclopædia Britannica
  

v t e Periodic table (Large cells)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1 H He 2 Li Be B C N O F Ne 3 Na Mg Al Si P S Cl Ar 4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 5 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 6 Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 7 Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
Alkali metal Alkaline earth metal Lan­thanide Actinide Transition metal Post-​transition metal Metalloid Reactive nonmetal Noble gas Unknown chemical properties

v t e Potassium compounds
KAsO2 KBr KBrO3 KCN KCNO KCl KClO KClO3 KClO4 KF KH KHCO2 KHCO3 KHF2 KHS KHSO3 KHSO4 KH2AsO4 KH2PO3 KH2PO4 KI KIO3 KIO4 KMnO4 KN3 KNH2 KNO2 KNO3 KOCN KOH KO2 KPF6 KSCN KCH3COO K2Al2O4 K2CO3 K2CrO4 K2Cr2O7 K2FeO4 K2HPO4 K2MnO4 K2O K2O2 K2PtCl4 K2PtCl6 K2S K2SeO4 K2SO3 K2SO4 KHSO5 K2S2O5 K2S2O7 K2S2O8 K2Po K2SiO3 K3[Fe(CN)6] K3[Fe(C2O4)3] K4[Fe(CN)6] K3PO4 K4Mo2Cl8

Authority control	BNF: cb121440770 (data) GND: 4139553-0 LCCN: sh85105593 NDL: 00565080

This page is only for reference, If you need detailed information, please check here