| Calcium chloride | |
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Calcium chloride |
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Other names
Calcium(II) chloride, |
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| Identifiers | |
| CAS number | 10043-52-4 , 22691-02-7 (monohydrate) 10035-04-8 (dihydrate) 25094-02-4 (tetrahydrate) 7774-34-7 (hexahydrate) |
| PubChem | 24854 |
| ChemSpider | 23237 |
| UNII | OFM21057LP |
| EC number | 233-140-8 |
| DrugBank | DB01164 |
| ChEBI | CHEBI:3312 |
| ChEMBL | CHEMBL1200668 |
| RTECS number | EV9800000 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | CaCl2 |
| Appearance | white powder |
| Density | 2.15 g/cm3 (anhydrous) 1.835 g/cm3 (dihydrate) 1.83 g/cm3 (tetrahydrate) 1.71 g/cm3 (hexahydrate) |
| Melting point |
772 °C (anhydrous) |
| Boiling point |
1935 °C (anhydrous) |
| Solubility in water | 74.5 g/100mL (20 °C) 59.5 g/100 mL (0 °C) |
| Solubility in alcohol | soluble |
| Acidity (pKa) | 8-9 (anhydrous) 6.5-8.0 (hexahydrate) |
| Structure | |
| Crystal structure | Orthorhombic (deformed rutile), oP6 |
| Space group | Pnnm, No. 58 |
| Coordination geometry |
octahedral, 6-coordinate |
| Hazards | |
| MSDS | External MSDS |
| EU Index | 017-013-00-2 |
| EU classification | Irritant (Xi) |
| R-phrases | R36 |
| S-phrases | (S2), S22, S24 |
| NFPA 704 |
0
2
1
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| LD50 | 1000 mg/kg (oral, rat) |
| Related compounds | |
| Other anions | calcium fluoride calcium bromide calcium iodide |
| Other cations | Beryllium chloride Magnesium chloride Strontium chloride Barium chloride Radium chloride |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
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. Because of its hygroscopic nature, anhydrous calcium chloride must be kept in tightly-sealed air-tight containers.
Contents |
Calcium chloride can serve as a source of calcium ions in a solution as calcium chloride is soluble. This property can be useful for displacing ions from solution. For example, phosphate is displaced from solution by calcium:
Molten calcium chloride can be electrolysed to give calcium metal and chlorine gas:
Calcium chloride has a very high enthalpy change of solution.
The anhydrous salt is deliquescent; it can accumulate enough water in its crystal lattice to form a solution.
Calcium chloride can be produced directly from limestone, but large amounts are also produced as a by-product of the Solvay process. North American consumption in 2002 was 1,687,000 tons (3.7 billion pounds).[2] A Dow Chemical Company manufacturing facility in Michigan, houses about 35% of the total U.S. production capacity for calcium chloride.[3]
Calcium chloride occurs as the rare evaporite minerals sinjarite (dihydrate) and antarcticite (hexahydrate). A related mineral chlorocalcite (potassium calcium chloride, KCaCl3) is also very rare.
Drying tubes are frequently packed with calcium chloride. Kelp is dried with calcium chloride for use producing sodium carbonate. Adding solid calcium chloride to liquids can remove dissolved water. Calcium chloride is also used in products such as DampRid and Dri-Z-Air which is advertised as an air moisture absorber. Anhydrous calcium chloride has been approved by the FDA as a packaging aid to ensure dryness (CPG 7117.02).[4]
These hygroscopic properties are also applied to keep a liquid layer on the surface of the roadway, which holds dust down.[5]
By depressing the freezing-point calcium chloride is used to prevent ice formation and to deice. This is particularly useful on road surfaces. Calcium chloride dissolution is exothermic, and is relatively harmless to plants and soil; however, recent observations in Washington state suggest it may be particularly harsh on roadside evergreen trees.[6] It is also more effective at lower temperatures than sodium chloride. When distributed for this use, it usually takes the form of small white balls a few millimeters in diameter, called prills. Solutions of calcium chloride can prevent freezing at temperature as low as −52 °C (−62 °F), making it ideal for filling agricultural implement tires as a liquid ballast, aiding traction in cold climates.[7]
Calcium chloride is used to increase the hardness in swimming pools. This reduces the erosion of the concrete in the pool. By Le Chatelier's principle and the common ion effect, increasing the concentration of calcium in the water will reduce the dissolution of calcium compounds essential to the structure of concrete.
In marine aquariums calcium chloride is added to introduce bioavailable calcium for calcium carbonate shelled animals such as mollusks and cnidarians. Calcium hydroxide (kalkwasser mix) or a calcium reactor can also be used to introduce calcium, however calcium chloride addition is the fastest method and has minimal impact on pH.
As an ingredient, it is listed as a permitted food additive in the European Union for use as a sequestrant and firming agent with the E number E509, and considered as generally recognized as safe (GRAS) by the U.S. Food and Drug Administration.[8] The average intake of calcium chloride as food additives has been estimated to be 160–345 mg/day for individuals.[9]
As a firming agent calcium chloride is used in canned vegetables, in firming soy bean curds into tofu and in producing a caviar substitute from vegetable or fruit juices.[10] It is commonly used as an electrolyte in sports drinks and other beverages including Smartwater and Nestle bottled water. The extremely salty taste of calcium chloride is used to flavor pickles while not increasing the food's sodium content. Calcium chloride's freezing-point depression properties are used, for example, in Cadbury Caramilk chocolate bars to slow the freezing of the caramel.
In brewing 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. Calcium chloride is sometimes added to processed milk to restore the natural balance between calcium and protein in casein for the purposes of making cheese such as brie, Pélardon and stilton. Finally, it is frequently added to pre-cut apple slices in order to maintain texture.
Calcium chloride can be injected as intravenous therapy for the treatment of hypocalcaemia. It can be used for magnesium intoxication. Calcium chloride injection may antagonize cardiac toxicity as measured by electrocardiogram. It can help to protect the myocardium from dangerously high levels of serum potassium in hyperkalemia. Calcium chloride can be used to quickly treat Calcium Channel Blocker toxicity, from the side effects of drugs such as Cardizem — helping avoid potential heart attacks. [11]
Aqueous calcium chloride is used in genetic transformation of cells by increasing the cell membrane permeability, inducing competence for DNA uptake (allowing DNA fragments to enter the cell more readily).
Calcium chloride is used in concrete mixes to help speed up the initial setting, but chloride ion leads to corrosion of steel rebar, so it should not be used in reinforced concrete.[12] The anhydrous form of calcium chloride may also be used for this purpose and can provide a measure of the moisture in concrete.[13]
Calcium chloride is used in swimming pool water as a pH buffer and to adjust the calcium hardness of the water.
Calcium chloride is included as an additive in plastics and in fire extinguishers, in wastewater treatment as a drainage aid, in blast furnaces 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 calcium chloride is used to increase the density of solids free brines. It is also used to provide inhibition of swelling clays in the water phase of invert emulsion drilling fluids.
Calcium chloride can act as an irritant by desiccating moist skin. Solid calcium chloride dissolves exothermically and burns can result in the mouth and esophagus if calcium chloride is ingested. Ingestion of concentrated solutions or solid calcium chloride products may cause gastrointestinal irritation or ulceration.[14]
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