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Calcium chloride is an
inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemis ...
, a
salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...
with the
chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...
. It is a white crystalline solid at room temperature, and it is highly soluble in water. It can be created by neutralising
hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dige ...
with
calcium hydroxide Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca( OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed or slaked with water. It has ma ...
. Calcium chloride is commonly encountered as a hydrated solid with generic formula , where ''n'' = 0, 1, 2, 4, and 6. These compounds are mainly used for de-icing and dust control. Because the
anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achi ...
salt is hydroscopic and deliquescent, it is used as a
desiccant A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant. Commonly encountered pre-packaged desiccants are solids that absorb water. Desiccants ...
.Robert Kemp, Suzanne E. Keegan "Calcium Chloride" in Ullmann's Encyclopedia of Industrial Chemistry 2000, Wiley-VCH, Weinheim.


Uses


De-icing and freezing-point depression

By depressing the freezing point of water, calcium chloride is used to prevent ice formation and is used to de-ice. This application consumes the greatest amount of calcium chloride. Calcium chloride is relatively harmless to plants and soil. As a deicing agent, it is much more effective at lower temperatures than
sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35. ...
. When distributed for this use, it usually takes the form of small, white spheres a few millimeters in diameter, called
prills A prill is a small aggregate or globule of a material, most often a dry sphere, formed from a melted liquid through spray crystallization. Prilled is a term used in mining and manufacturing to refer to a product that has been pelletized. ANFO e ...
. Solutions of calcium chloride can prevent freezing at temperatures as low as −52 °C (−62 °F), making it ideal for filling agricultural implement tires as a liquid ballast, aiding traction in cold climates. It is also used in domestic and industrial chemical air dehumidifiers.


Road surfacing

The second largest application of calcium chloride exploits its
hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance' ...
nature and the tackiness of its hydrates; calcium chloride is highly hygroscopic and its hydration is an exothermic process. A concentrated solution keeps a liquid layer on the surface of dirt roads, which suppresses the formation of dust. It keeps the finer dust particles on the road, providing a cushioning layer. If these are allowed to blow away, the large aggregate begins to shift around and the road breaks down. Using calcium chloride reduces the need for grading by as much as 50% and the need for fill-in materials as much as 80%.


Food

The average intake of calcium chloride as food additives has been estimated to be 160–345 mg/day. Calcium chloride is permitted as a food additive in the
European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...
for use as a sequestrant and
firming agent Firming agents are food additives added in order to precipitate residual pectin, thus strengthening the structure of the food and preventing its collapse during processing. These are salts, typically lactates or phosphates, calcium salts or alumi ...
with the
E number E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...
E509. It is considered as generally recognized as safe (GRAS) by the U.S. Food and Drug Administration. Its use in organic crop production is generally prohibited under the US National Organic Program.7 CFRbr>§ 205.602
/ref> In marine aquariums, calcium chloride is one way to introduce bioavailable calcium for calcium carbonate-shelled animals such as
mollusks Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000  extant species of molluscs are recognized. The number of fossil species is esti ...
and some cnidarians.
Calcium hydroxide Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca( OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed or slaked with water. It has ma ...
(
limewater Limewater is the common name for a saturated aqueous solution of calcium hydroxide. Calcium hydroxide, Ca(OH)2, is sparsely soluble at room temperature in water (1.5 g/L at 25 °C). "Pure" (i.e. less than or fully saturated) limewater i ...
) or a
calcium reactor __NOTOC__ In marine and reef aquariums, a calcium reactor creates a balance of alkalinity. An acidic solution is produced by injecting carbon dioxide into a chamber with salt water and calcium rich media. The carbon dioxide lowers the pH by prod ...
can also be used. As a
firming agent Firming agents are food additives added in order to precipitate residual pectin, thus strengthening the structure of the food and preventing its collapse during processing. These are salts, typically lactates or phosphates, calcium salts or alumi ...
, calcium chloride is used in canned vegetables, in firming
soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean, which has numerous uses. Traditional unfermented food uses of soybeans include soy milk, from which tofu ...
curds into tofu and in producing a caviar substitute from vegetable or fruit juices. It is commonly used as an
electrolyte An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon ...
in sports drinks and other beverages, including bottled water. The extremely salty taste of calcium chloride is used to flavor pickles without increasing the food's
sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...
content. Calcium chloride's freezing-point depression properties are used to slow the freezing of the caramel in caramel-filled chocolate bars. Also, it is frequently added to sliced apples to maintain texture. In
brewing Brewing is the production of beer by steeping a starch source (commonly cereal grains, the most popular of which is barley) in water and fermenting the resulting sweet liquid with yeast. It may be done in a brewery by a commercial brewer ...
beer, calcium chloride is sometimes used to correct mineral deficiencies in the brewing water. It affects flavor and chemical reactions during the brewing process, and can also affect yeast function during fermentation. In
cheesemaking Cheesemaking (or caseiculture) is the craft of making cheese. The production of cheese, like many other food preservation processes, allows the nutritional and economic value of a food material, in this case milk, to be preserved in concentr ...
, calcium chloride is sometimes added to processed (pasteurized/homogenized) milk to restore the natural balance between calcium and protein in
casein Casein ( , from Latin ''caseus'' "cheese") is a family of related phosphoproteins ( αS1, aS2, β, κ) that are commonly found in mammalian milk, comprising about 80% of the proteins in cow's milk and between 20% and 60% of the proteins in hum ...
. It is added before the coagulant. Calcium chloride is used to prevent
cork spot Cork or CORK may refer to: Materials * Cork (material), an impermeable buoyant plant product ** Cork (plug), a cylindrical or conical object used to seal a container ***Wine cork Places Ireland * Cork (city) ** Metropolitan Cork, also known as G ...
and bitter pit on apples by spraying on the tree during the late growing season.


Laboratory and related drying operations

Drying tubes are frequently packed with calcium chloride. Kelp is dried with calcium chloride for use in producing
sodium carbonate Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions ...
. Anhydrous calcium chloride has been approved by the FDA as a packaging aid to ensure dryness (CPG 7117.02). The hydrated salt can be dried for re-use but will dissolve in its own water of hydration if heated quickly and form a hard amalgamated solid when cooled.


Other applications

Calcium chloride is used in concrete mixes to accelerate the initial setting, but chloride ions lead to corrosion of steel
rebar Rebar (short for reinforcing bar), known when massed as reinforcing steel or reinforcement steel, is a steel bar used as a tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concrete under tension. ...
, so it should not be used in
reinforced concrete Reinforced concrete (RC), also called reinforced cement concrete (RCC) and ferroconcrete, is a composite material in which concrete's relatively low ultimate tensile strength, tensile strength and ductility are compensated for by the inclusion ...
. The anhydrous form of calcium chloride may also be used for this purpose and can provide a measure of the moisture in concrete. Calcium chloride is included as an additive in plastics and in fire extinguishers, in
blast furnace A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. ''Blast'' refers to the combustion air being "forced" or supplied above atmospheri ...
s as an additive to control scaffolding (clumping and adhesion of materials that prevent the furnace charge from descending), and in fabric softener as a thinner. The exothermic dissolution of calcium chloride is used in self-heating cans and heating pads. In the
oil industry The petroleum industry, also known as the oil industry or the oil patch, includes the global processes of exploration, extraction, refining, transportation (often by oil tankers and pipelines), and marketing of petroleum products. The larges ...
, calcium chloride is used to increase the density of solids-free
brine Brine is a high-concentration solution of salt (NaCl) in water (H2O). In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of that of solutions used for ...
s. It is also used to provide inhibition of swelling clays in the water phase of invert
emulsion An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Alth ...
drilling fluids. acts as flux material, decreasing the melting point, in the Davy process for the industrial production of sodium metal through the
electrolysis In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from n ...
of molten NaCl. Calcium chloride is also used in the production of
activated charcoal "Activated" is a song by English singer Cher Lloyd. It was released on 22 July 2016 through Vixen Records. The song was made available to stream exclusively on ''Rolling Stone'' a day before to release (on 21 July 2016). Background In an inter ...
. Calcium chloride can be used to precipitate
fluoride Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts ty ...
ions from water as insoluble . Calcium chloride is also an ingredient used in ceramic slipware. It suspends clay particles so that they float within the solution, making it easier to use in a variety of slipcasting techniques. Calcium chloride dihydrate (20 percent by weight) dissolved in
ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
(95 percent ABV) has been used as a
sterilant Sterilization refers to any process that removes, kills, or deactivates all forms of life (particularly microorganisms such as fungi, bacteria, spores, and unicellular eukaryotic organisms) and other biological agents such as prions present in o ...
for male animals. The solution is injected into the testes of the animal. Within one month,
necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated diges ...
of testicular tissue results in sterilization.
Cocaine Cocaine (from , from , ultimately from Quechua: ''kúka'') is a central nervous system (CNS) stimulant mainly used recreationally for its euphoric effects. It is primarily obtained from the leaves of two Coca species native to South Am ...
producers in
Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the ...
import tons of calcium chloride to recover solvents that are on the
INCB Red List The International Narcotics Control Board (INCB) is an independent treaty body, one of the four treaty-mandated bodies under international drug control law (alongside the Commission on Narcotic Drugs, UNODC on behalf of the Secretary-General, an ...
and are more tightly controlled.


Metal reduction flux

Similarly, is used as a flux and
electrolyte An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon ...
in the FFC Cambridge electrolysis process for
titanium Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion i ...
production, where it ensures the proper exchange of calcium and oxygen ions between the electrodes.


Hazards

Although non-toxic in small quantities when wet, the strongly
hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance' ...
properties of the non-hydrated salt present some hazards. Calcium chloride can act as an irritant by
desiccating Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. ...
moist skin. Solid calcium chloride dissolves exothermically, and burns can result in the
mouth In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on ...
and
esophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to t ...
if it is ingested. Ingestion of concentrated solutions or solid products may cause gastrointestinal irritation or ulceration. Consumption of calcium chloride can lead to
hypercalcemia Hypercalcemia, also spelled hypercalcaemia, is a high calcium (Ca2+) level in the blood serum. The normal range is 2.1–2.6  mmol/L (8.8–10.7 mg/dL, 4.3–5.2 mEq/L), with levels greater than 2.6 mmol/L defined as hypercalcem ...
.


Properties

Calcium chloride dissolves in water, producing chloride and the aquo complex . In this way, these solutions are sources of "free" calcium and free chloride ions. This description is illustrated by the fact that these solutions react with
phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosph ...
sources to give a solid precipitate of calcium phosphate: : Calcium chloride has a very high enthalpy change of solution, indicated by considerable temperature rise accompanying dissolution of the anhydrous salt in water. This property is the basis for its largest-scale application. Molten calcium chloride can be electrolysed to give
calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...
metal and
chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
gas: :


Preparation

In much of the world, calcium chloride is derived from
limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...
as a by-product of the Solvay process, which follows the net reaction below: : North American consumption in 2002 was 1,529,000
tonne The tonne ( or ; symbol: t) is a unit of mass equal to 1000  kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s (3.37 billion pounds). In the US, most of calcium chloride is obtained by purification from
brine Brine is a high-concentration solution of salt (NaCl) in water (H2O). In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of that of solutions used for ...
. As with most bulk commodity salt products, trace amounts of other
cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...
s from the
alkali metal The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names ...
s and alkaline earth metals (
groups A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic ide ...
1 and 2) and other
anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...
s from the
halogen The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this grou ...
s ( group 17) typically occur, but the
concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', '' molar concentration'', ''number concentration'', ...
s are trifling.


Occurrence

Calcium chloride occurs as the rare evaporite minerals sinjarite (dihydrate) and antarcticite (hexahydrate). Another natural hydrate known is ghiaraite – a tetrahydrate. The related minerals
chlorocalcite Chlorocalcite is a rare potassium calcium chloride evaporite mineral with formula: KCaCl3. It is found in active volcanic fumaroles. It was first described in 1872 for an occurrence on Mount Vesuvius and given the name for its calcium content pr ...
(potassium calcium chloride, ) and
tachyhydrite Tachyhydrite is an unstable mineral, a hydrous chloride of calcium and magnesium with formula: Ca Mg2 Cl6·12 H2O. It is a rare component of marine evaporite salt deposits. Upon exposure to moist air it rapidly deliquesces and dissolves. It fo ...
(calcium magnesium chloride, ) are also very rare. So is true for rorisite, CaClF (calcium chloride fluoride).


See also

* Calcium(I) chloride * Calcium chloride transformation * Magnesium chloride


References

*


External links


International Chemical Safety Card 1184Product and Application Information (Formerly Dow Chemical Calcium Chloride division)Report on steel corrosion by chloride including CaCl2Collection of calcium chloride reports and articlesCalcium chloride, Anhydrous MSDSDifusivity of calcium chloride
National Institutes of Occupational Safety and Health, "Calcium Chloride (anhydrous)" {{DEFAULTSORT:Calcium Chloride Calcium compounds Chlorides Alkaline earth metal halides Deliquescent substances Desiccants Pyrotechnic colorants Edible salt E-number additives Concrete admixtures