Potassium chloride

Potassium chloride

Overview
The chemical compound
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 potassium chloride (KCl) is a metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

 halide
Halide
A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts are halides...

 salt composed of potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

 and chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

. In its pure state, it is odor
Odor
An odor or odour is caused by one or more volatilized chemical compounds, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction. Odors are also commonly called scents, which can refer to both pleasant and unpleasant odors...

less and has a white or color
Color
Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...

less vitreous crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

 appearance, with a crystal structure
Crystal structure
In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...

 that cleaves easily in three directions. Potassium chloride crystals are face-centered cubic. Potassium chloride was historically known as "muriate of potash," this name is occasionally still encountered in association with its use as a fertilizer
Fertilizer
Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...

.
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Encyclopedia
The chemical compound
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 potassium chloride (KCl) is a metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

 halide
Halide
A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts are halides...

 salt composed of potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

 and chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

. In its pure state, it is odor
Odor
An odor or odour is caused by one or more volatilized chemical compounds, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction. Odors are also commonly called scents, which can refer to both pleasant and unpleasant odors...

less and has a white or color
Color
Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...

less vitreous crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

 appearance, with a crystal structure
Crystal structure
In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...

 that cleaves easily in three directions. Potassium chloride crystals are face-centered cubic. Potassium chloride was historically known as "muriate of potash," this name is occasionally still encountered in association with its use as a fertilizer
Fertilizer
Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...

. Potash
Potash
Potash is the common name for various mined and manufactured salts that contain potassium in water-soluble form. In some rare cases, potash can be formed with traces of organic materials such as plant remains, and this was the major historical source for it before the industrial era...

 varies in color from pink or red to white depending on the mining
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

 and recovery process used. White potash, sometimes referred to as soluble potash, is usually higher in analysis and is used primarily for making liquid starter fertilizer
Fertilizer
Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...

s. KCl is used in medicine
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

, scientific applications, and food processing
Food preservation
Food preservation is the process of treating and handling food to stop or slow down spoilage and thus allow for longer storage....

. It occurs naturally as the mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

 sylvite
Sylvite
Sylvite is potassium chloride in natural mineral form. It forms crystals in the isometric system very similar to normal rock salt, halite . The two are, in fact, isomorphous. Sylvite is colorless to white with shades of yellow and red due to inclusions. It has a Mohs hardness of 2.5 and a specific...

 and in combination with sodium chloride
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

 as sylvinite
Sylvinite
Sylvinite is the most important ore for the production of potash in North America. It is a mechanical mixture of sylvite and halite . Most Canadian operations mine sylvinite with proportions of about 31% KCl and 66% NaCl with the balance being insoluble clays, anhydrite and in some locations...

.

Chemical properties


In chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

 and physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

, it is a very commonly used standard, for example as a calibration
Calibration
Calibration is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device....

 standard solution in measuring electrical conductivity of (ionic) solutions, since carefully prepared KCl solutions have well-reproducible and well-repeatable measurable properties.
Potassium chloride can react as a source of chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...

 ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

. As with any other soluble
Solubility
Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a homogeneous solution of the solute in the solvent. The solubility of a substance fundamentally depends on the used solvent as well as on...

 ionic chloride, it will precipitate insoluble chloride salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

s when added to a solution
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...

 of an appropriate metal ion:
KCl(aq) + AgNO3
Silver nitrate
Silver nitrate is an inorganic compound with chemical formula . This compound is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides...

(aq) → AgCl(s
Solid
Solid is one of the three classical states of matter . It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a...

) + KNO3(aq)


Although potassium is more electropositive than sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

, KCl can be reduced to the metal by reaction with metallic sodium at 850°C because the potassium is removed by distillation (see Le Chatelier's principle
Le Châtelier's principle
In chemistry, Le Chatelier's principle, also called the Chatelier's principle, can be used to predict the effect of a change in conditions on a chemical equilibrium. The principle is named after Henry Louis Le Chatelier and sometimes Karl Ferdinand Braun who discovered it independently...

):
KCl(l) + Na(l) ⇌ NaCl(l) + K(g)


This method is the main method for producing metallic potassium. Electrolysis
Electrolysis
In chemistry and manufacturing, electrolysis is a method of using a direct electric current to drive an otherwise non-spontaneous chemical reaction...

 (used for sodium) fails because of the high solubility of potassium in molten KCl.

As with other compounds containing potassium, KCl in powdered form gives a lilac flame test
Flame test
A flame test is a procedure used in chemistry to detect the presence of certain metal ions, based on each element's characteristic emission spectrum. The color of flames in general also depends on temperature; see flame color....

 result.

Physical properties


Potassium chloride has a crystalline structure like many other salts. Its structure is face-centered cubic. Its lattice
Crystal structure
In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...

 constant is roughly 630 picometers. Some other properties are
  • Transmission range: 210 nm to 20 µm
  • Transmittivity
    Transmittance
    In optics and spectroscopy, transmittance is the fraction of incident light at a specified wavelength that passes through a sample. A related term is absorptance, or absorption factor, which is the fraction of radiation absorbed by a sample at a specified wavelength...

     = 92% at 450 nm and rises linearly to 94% at 16 µm
  • Refractive index = 1.456 at 10 µm
  • Reflection Loss = 6.8% at 10 µm (two surfaces)
  • dN/dT (expansion coefficient)= −33.2×10−6/°C
  • dL/dT (refractive index gradient)= 40×10−6/°C
  • Thermal conductivity = 0.036 W/(cm·K)
  • Damage threshold (Newman & Novak): 4 GW/cm2 or 2 J/cm2 (0.5 or 1 ns pulse rate); 4.2 J/cm2 (1.7 ns pulse rate Kovalev & Faizullov)

Production


Potassium chloride occurs naturally as sylvite
Sylvite
Sylvite is potassium chloride in natural mineral form. It forms crystals in the isometric system very similar to normal rock salt, halite . The two are, in fact, isomorphous. Sylvite is colorless to white with shades of yellow and red due to inclusions. It has a Mohs hardness of 2.5 and a specific...

, and it can be extracted from sylvinite
Sylvinite
Sylvinite is the most important ore for the production of potash in North America. It is a mechanical mixture of sylvite and halite . Most Canadian operations mine sylvinite with proportions of about 31% KCl and 66% NaCl with the balance being insoluble clays, anhydrite and in some locations...

. It is also extracted from salt water
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...

 and can be manufactured by crystallization from solution
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...

, flotation
Flotation process
Flotation process is a method of separation widely used in the wastewater treatment and mineral processing industries.Various flotation processes include the following:* Dissolved air flotation...

 or electrostatic separation from suitable minerals. It is a by-product of the making of nitric acid
Nitric acid
Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...

 from potassium nitrate
Potassium nitrate
Potassium nitrate is a chemical compound with the formula KNO3. It is an ionic salt of potassium ions K+ and nitrate ions NO3−.It occurs as a mineral niter and is a natural solid source of nitrogen. Its common names include saltpetre , from medieval Latin sal petræ: "stone salt" or possibly "Salt...

 and hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....

.

Uses


The majority of the potassium chloride produced is used for making fertilizer
Fertilizer
Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...

, since the growth of many plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s is limited by their potassium intake. As a chemical feedstock, it is used for the manufacture of potassium hydroxide
Potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula KOH, commonly called caustic potash.Along with sodium hydroxide , this colorless solid is a prototypical strong base. It has many industrial and niche applications. Most applications exploit its reactivity toward acids and its corrosive...

 and potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

 metal. It is also used in medicine, lethal injection
Lethal injection
Lethal injection is the practice of injecting a person with a fatal dose of drugs for the express purpose of causing the immediate death of the subject. The main application for this procedure is capital punishment, but the term may also be applied in a broad sense to euthanasia and suicide...

s, scientific
Science
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...

 applications, food processing
Food processing
Food processing is the set of methods and techniques used to transform raw ingredients into food or to transform food into other forms for consumption by humans or animals either in the home or by the food processing industry...

, and as a sodium-free substitute for table salt
Edible salt
Salt, also known as table salt, or rock salt, is a mineral that is composed primarily of sodium chloride , a chemical compound belonging to the larger class of ionic salts. It is essential for animal life in small quantities, but is harmful to animals and plants in excess...

 (sodium chloride).

It is sometimes used in water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 as a completion
Completion (oil and gas wells)
In petroleum production, completion is the process of making a well ready for production . This principally involves preparing the bottom of the hole to the required specifications, running in the production tubing and its associated down hole tools as well as perforating and stimulating as...

 fluid in petroleum
Petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...

 and natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

 operations, as well as being an alternative to sodium chloride
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

 in household water softener units. KCl is useful as a beta radiation source for calibration
Calibration
Calibration is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device....

 of radiation monitoring equipment, because natural potassium contains 0.0118% of the isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...

 40K. One kilogram
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...

 of KCl yields 16350 becquerel
Becquerel
The becquerel is the SI-derived unit of radioactivity. One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. The Bq unit is therefore equivalent to an inverse second, s−1...

s of radiation
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...

 consisting of 89.28% beta and 10.72% gamma
Gamma ray
Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency . Gamma rays are usually naturally produced on Earth by decay of high energy states in atomic nuclei...

 with 1.46083 MeV. Potassium chloride is used in some Deicing
Deicing
For snow and ice control on roadways and similar facilities, see Snow removalDe-icing is defined as removal of snow, ice or frost from a surface...

 products that are designed to be safer for pets and plants, though these are inferior in melting quality to calcium chloride
Calcium chloride
Calcium chloride, CaCl2, is a salt of calcium and chlorine. It behaves as a typical ionic halide, and is solid at room temperature. Common applications include brine for refrigeration plants, ice and dust control on roads, and desiccation...

 (lowest usable temperature 0 °F (-17.8 °C) v. -25 F). It is also used in various brands of bottled water
Bottled water
Bottled water is drinking water packaged in plastic or glass water bottles. Bottled water may be carbonated or not...

, as well as in bulk quantities for fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...

 drilling
Drilling
Drilling is a cutting process that uses a drill bit to cut or enlarge a hole in solid materials. The drill bit is a multipoint, end cutting tool...

 purposes.

Potassium chloride was once used as a fire extinguishing agent
Fire retardant
A fire retardant is a substance other than water that reduces flammability of fuels or delays their combustion. This typically refers to chemical retardants but may also include substances that work by physical action, such as cooling the fuels; examples of these include fire-fighting foams and...

, used in portable and wheeled fire extinguisher
Fire extinguisher
A fire extinguisher or extinguisher, flame entinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations...

s. Known as Super-K dry chemical, it was more effective than sodium bicarbonate
Sodium bicarbonate
Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula Na HCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda . The natural mineral form is...

-based dry chemicals and was compatible with protein foam. This agent fell out of favor with the introduction of potassium bicarbonate
Potassium bicarbonate
Potassium bicarbonate , is a colorless, odorless, slightly basic, salty substance...

 (Purple-K
Purple-K
Purple-K is a dry-chemical fire suppression agent used in some dry powder fire extinguishers. It is the most effective dry chemical in fighting class B fires, and can be used against some energized electrical equipment fires...

) dry chemical in the late 1960s, which was much less corrosive
Corrosive
A corrosive substance is one that will destroy or irreversibly damage another surface or substance with which it comes into contact. The main hazards to people include damage to the eyes, the skin, and the tissue under the skin; inhalation or ingestion of a corrosive substance can damage the...

 and more effective. It is rated for B and C fires.

Along with sodium chloride
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

 and lithium chloride
Lithium chloride
Lithium chloride is a chemical compound with the formula LiCl. The salt is a typical ionic compound, although the small size of the Li+ ion gives rise to properties not seen for other alkali metal chlorides, such as extraordinary solubility in polar solvents and its hygroscopic...

, potassium chloride is used as a flux
Flux (metallurgy)
In metallurgy, a flux , is a chemical cleaning agent, flowing agent, or purifying agent. Fluxes may have more than one function at a time...

 for the gas welding of aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

.

Potassium chloride is also an optical crystal with a wide transmission range from 210 nm to 20 µm. While cheap, KCl crystal is hygroscopic. This limits its application to protected environments or short term uses such as prototyping. Exposed to free air, KCl optics will "rot". Whereas KCl components were formerly used for infrared optics, it has been entirely replaced by much tougher crystals like ZnSe
Zinc selenide
Zinc selenide , is a light yellow binary solid compound. It is an intrinsic semiconductor with a band gap of about 2.70 eV at 25 °C. ZnSe rarely occurs in nature...

.

Potassium chloride has also been used to create heat packs
Heating pad
A heating pad is a pad used for warming of parts of the body in order to manage pain. Localized application of heat causes the blood vessels in that area to dilate, enhancing perfusion to the targeted tissue...

 which employ exothermic
Exothermic
In thermodynamics, the term exothermic describes a process or reaction that releases energy from the system, usually in the form of heat, but also in the form of light , electricity , or sound...

 chemical reaction
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...

s, but these are no longer being created due to cheaper and more efficient methods, such as the oxidation of metals ('Hot Hands', one time use products) or the crystallization
Crystallization
Crystallization is the process of formation of solid crystals precipitating from a solution, melt or more rarely deposited directly from a gas. Crystallization is also a chemical solid–liquid separation technique, in which mass transfer of a solute from the liquid solution to a pure solid...

 of sodium acetate
Sodium acetate
Sodium acetate, CH3COONa, also abbreviated NaOAc, also sodium ethanoate, is the sodium salt of acetic acid. This colourless salt has a wide range of uses.-Industrial:...

 (multiple use products).

Potassium chloride is used as a scotophor
Scotophor
A scotophor is a material showing reversible darkening and bleaching when subjected to certain types of radiation. The name means dark bearer, in contrast to phosphor, which means light bearer. Scotophors show tenebrescence and darken when subjected to an intense radiation such as sunlight...

 with designation P10 in dark-trace CRTs, e.g. in the Skiatron.

Biological and medical properties


Potassium is vital in the human body
Human body
The human body is the entire structure of a human organism, and consists of a head, neck, torso, two arms and two legs.By the time the human reaches adulthood, the body consists of close to 100 trillion cells, the basic unit of life...

, and oral potassium chloride is the common means to replenish it, although it can also be diluted and given intravenously
Intravenous therapy
Intravenous therapy or IV therapy is the infusion of liquid substances directly into a vein. The word intravenous simply means "within a vein". Therapies administered intravenously are often called specialty pharmaceuticals...

. It can be used as a salt substitute
Salt substitute
Salt substitutes are low-sodium table salt alternatives marketed to circumvent the risk of high blood pressure and cardiovascular disease associated with a high intake of sodium chloride while maintaining a similar taste...

 for food
Food
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...

, but due to its weak, bitter, unsalty flavour, it is usually mixed with ordinary salt (sodium chloride) for this purpose to improve the taste
Taste
Taste is one of the traditional five senses. It refers to the ability to detect the flavor of substances such as food, certain minerals, and poisons, etc....

. The addition of 1 ppm of thaumatin
Thaumatin
Thaumatin is a low-calorie sweetener and flavour modifier. The substance, a natural protein, is often used primarily for its flavour-modifying properties and not exclusively as a sweetener....

 considerably reduces this bitterness. Medically, it is used in the treatment of hypokalemia
Hypokalemia
Hypokalemia or hypokalaemia , also hypopotassemia or hypopotassaemia , refers to the condition in which the concentration of potassium in the blood is low...

 and associated conditions, for digitalis
Digitalis
Digitalis is a genus of about 20 species of herbaceous perennials, shrubs, and biennials that are commonly called foxgloves. This genus was traditionally placed in the figwort family Scrophulariaceae, but recent reviews of phylogenetic research have placed it in the much enlarged family...

 poison
Poison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....

ing, and as an electrolyte
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....

 replenisher. Brand names include K-Dur, Klor-Con, Micro-K, Slow-K and Kaon Cl. Side effects can include gastrointestinal
Gastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....

 discomfort including nausea
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...

 and vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...

, diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...

 and bleeding
Bleeding
Bleeding, technically known as hemorrhaging or haemorrhaging is the loss of blood or blood escape from the circulatory system...

 of the digestive tract. Overdoses cause hyperkalemia
Hyperkalemia
Hyperkalemia refers to the condition in which the concentration of the electrolyte potassium in the blood is elevated...

, which can lead to paresthesia
Paresthesia
Paresthesia , spelled "paraesthesia" in British English, is a sensation of tingling, burning, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep"...

, cardiac
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

 conduction blocks, fibrillation
Fibrillation
Fibrillation is the rapid, irregular, and unsynchronized contraction of muscle fibers. An important occurrence is with regards to the heart.-Cardiology:There are two major classes of cardiac fibrillation: atrial fibrillation and ventricular fibrillation....

, arrhythmias, and sclerosis
Sclerosis (medicine)
In medicine, sclerosis refers to the stiffening of a structure, usually caused by a replacement of the normal organ-specific tissue with connective tissue.Types include:...

. Prescription potassium citrate
Potassium citrate
Potassium citrate is a potassium salt of citric acid with the molecular formula C6H5K3O7. It is a white, slightly hygroscopic crystalline powder. It is odorless with a saline taste....

 (the potassium naturally found in fruits and vegetables) can be prescribed as an alternative to potassium chloride. Slow-K is a 1950s development where the medicine is formulated to enter the bloodstream at delayed intervals. It was first only prescribed to British military forces to balance their diets while serving in Korea.

Some cardiac surgery
Cardiac surgery
Cardiovascular surgery is surgery on the heart or great vessels performed by cardiac surgeons. Frequently, it is done to treat complications of ischemic heart disease , correct congenital heart disease, or treat valvular heart disease from various causes including endocarditis, rheumatic heart...

 procedures cannot be carried out on the beating heart. For these procedures, the surgical team will bypass the heart with a heart-lung machine
Heart-lung machine
Cardiopulmonary bypass is a technique that temporarily takes over the function of the heart and lungs during surgery, maintaining the circulation of blood and the oxygen content of the body. The CPB pump itself is often referred to as a heart–lung machine or "the pump"...

 and inject potassium chloride into the heart muscle to stop the heartbeat. Some recently developed methods now allow surgery on the beating heart.

The lethal effects of potassium chloride overdoses have led to its use in lethal injection
Lethal injection
Lethal injection is the practice of injecting a person with a fatal dose of drugs for the express purpose of causing the immediate death of the subject. The main application for this procedure is capital punishment, but the term may also be applied in a broad sense to euthanasia and suicide...

,
as the third of a three-drug combination. Additionally, KCl is used (albeit rarely) in fetal intracardiac injections in second- and third-trimester induced abortions. Jack Kevorkian
Jack Kevorkian
Jacob "Jack" Kevorkian , commonly known as "Dr. Death", was an American pathologist, euthanasia activist, painter, composer and instrumentalist. He is best known for publicly championing a terminal patient's right to die via physician-assisted suicide; he said he assisted at least 130 patients to...

's thanatron machine injected a lethal dose of potassium chloride into the patient, which caused the heart to stop functioning, after a sodium thiopental
Sodium thiopental
Sodium thiopental, better known as Sodium Pentothal , thiopental, thiopentone sodium, or Trapanal , is a rapid-onset short-acting barbiturate general anaesthetic...

-induced coma was achieved. A similar device, the German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 'Perfusor', also uses potassium chloride as a suicide aid.

Precautions


Orally, potassium chloride is toxic in excess; the is around 2.5 g/kg (meaning that a lethal dose for 50% of people weighing 75 kg (165 lb
Pound (mass)
The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...

) is about 190 g (6.7 ounce
Ounce
The ounce is a unit of mass with several definitions, the most commonly used of which are equal to approximately 28 grams. The ounce is used in a number of different systems, including various systems of mass that form part of the imperial and United States customary systems...

s)). Intravenously, this is reduced to just over 100 mg/kg, but of more concern are its severe effects on the cardiac muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

s: high doses can cause cardiac arrest
Cardiac arrest
Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...

 and rapid death
Death
Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....

, thus the aforementioned use as the third and final drug delivered in the lethal injection process.