|CAS number||, (monohydrate) , (dihydrate) , (tetrahydrate) , (hexahydrate)|
|ATC code||A12,B05, G04|
|Jmol-3D images||Image 1|
|Molar mass||110.98 g mol−1|
|Appearance||White powder, hygroscopic|
|Density||2.15 g/cm3 (anhydrous)
2.24 g/cm3 (monohydrate)
1.85 g/cm3 (dihydrate)
1.83 g/cm3 (tetrahydrate)
1.71 g/cm3 (hexahydrate)
|Melting point||772–775 °C (1,422–1,427 °F; 1,045–1,048 K)
260 °C (500 °F; 533 K)
175 °C (347 °F; 448 K)
45.5 °C (113.9 °F; 318.6 K)
30 °C (86 °F; 303 K)
|Boiling point||1,935 °C (3,515 °F; 2,208 K)
|Solubility in water||Hexahydrate:
49.4 g/100 mL (−25 °C)
59.5 g/100 mL (0 °C)
65 g/100 mL (10 °C)
81.1 g/100 mL (25 °C)
102.2 g/100 mL (30.2 °C)
90.8 g/100 mL (20 °C)
114.4 g/100 mL (40 °C)
134.5 g/100 mL (60 °C)
152.4 g/100 mL (100 °C)
|Solubility||Soluble in CH3COOH, alcohols
Insoluble in liquid NH3, DMSO, CH3COOC2H5
|Solubility in ethanol||18.3 g/100 g (0 °C)
25.8 g/100 g (20 °C)
35.3 g/100 g (40 °C)
56.2 g/100 g (70 °C)
|Solubility in methanol||21.8 g/100 g (0 °C)
29.2 g/100 g (20 °C)
38.5 g/100 g (40 °C)
|Solubility in acetone||0.1 g/kg (20 °C)|
|Solubility in pyridine||16.6 g/kg|
|Acidity (pKa)||8–9 (anhydrous)
|Magnetic susceptibility||−5.47·10−5 cm3/mol|
|Refractive index (nD)||1.52|
|Viscosity||3.34 cP (787 °C)
1.44 cP (967 °C)
|Crystal structure||Orthorhombic (rutile, anhydrous), oP6
Tetragonal (anhydrous, > 217 °C), oP6
|Space group||Pnnm, No. 58 (anhydrous)
P42/mnm, No. 136 (anhydrous, > 217 °C)
|Point group||2/m 2/m 2/m (anhydrous)
4/m 2/m 2/m (anhydrous, > 217 °C)
|Lattice constant||a = 6.259 Å, b = 6.444 Å, c = 4.17 Å (anhydrous, 17 °C)|
|Lattice constant||α = 90°, β = 90°, γ = 90°|
|Octahedral (Ca2+, anhydrous)|
heat capacity C
|72.89 J/mol·K (anhydrous)
106.23 J/mol·K (monohydrate)
172.92 J/mol·K (dihydrate)
251.17 J/mol·K (tetrahydrate)
300.7 J/mol·K (hexahydrate)
|Std enthalpy of
|−795.42 kJ/mol (anhydrous)
−1110.98 kJ/mol (monohydrate)
−1403.98 kJ/mol (dihydrate)
−2009.99 kJ/mol (tetrahydrate)
− 2608.01 kJ/mol (hexahydrate)
|Gibbs free energy ΔG||−748.81 kJ/mol|
|GHS signal word||Warning|
|GHS hazard statements||H319|
|GHS precautionary statements||P305+351+338|
|LD50||1000 mg/kg (rats, oral)|
|Other anions||Calcium fluoride
|Other cations||Beryllium chloride
|Supplementary data page|
|n, εr, etc.|
Solid, liquid, gas
|Spectral data||UV, IR, NMR, MS|
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)|
|(what is: / ?)|
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.
Calcium chloride can serve as a source of calcium ions in an aqueous solution, as calcium chloride is soluble in water. This property can be useful for displacing ions from solution. For example, phosphate is displaced from solution by calcium:
- 3 CaCl2(aq) + 2 K3PO4(aq) → Ca3(PO4)2(s) + 6 KCl(aq)
- CaCl2(l) → Ca(s) + Cl2(g)
Calcium chloride has a very high enthalpy change of solution. A considerable temperature rise accompanies its dissolution in water.
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). A Dow Chemical Company manufacturing facility in Michigan houses about 35% of the total U.S. production capacity for calcium chloride.
Drying tubes are frequently packed with calcium chloride. Kelp is dried with calcium chloride for use in producing sodium carbonate. Adding solid calcium chloride to liquids can remove dissolved water. Anhydrous calcium chloride has been approved by the FDA as a packaging aid to ensure dryness (CPG 7117.02).
Deicing and freezing point depression
By depressing the freezing point of water, calcium chloride is used to prevent ice formation and to deice. This is particularly useful on road surfaces. Calcium chloride dissolution is exothermic, and the compound is relatively harmless to plants and soil; however, recent observations in Washington state suggest it may be particularly harsh on roadside evergreen trees. 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.
Swimming pools and aquariums
Calcium chloride is used to increase the water 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 some 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. 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 US National Organic Program's National List of Allowed and Prohibited Substances. The average intake of calcium chloride as food additives has been estimated to be 160–345 mg/day for individuals.
As a firming agent, calcium chloride is used in canned vegetables, in firming soybean curds into tofu and in producing a caviar substitute from vegetable or fruit juices. It is commonly used as an electrolyte in sports drinks and other beverages, including 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 to slow the freezing of the caramel in caramel-filled chocolate bars.
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 cheeses, such as brie, Pélardon and Stilton. Also, it is frequently added to sliced apples to maintain texture.
It is injected to treat internal hydrofluoric acid burns. It can be used to treat 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 diltiazem (Cardizem) — helping avoid potential heart attacks.
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 dihydrate (20% by weight) dissolved in ethanol (95% ABV) has been used as a sterilant for male animals. The non surgical procedure consists of the injection of the solution into the testes of the animal. Within 1 month, necrosis of testicular tissue results in sterilization.
Calcium chloride is used in concrete mixes to help speed up the initial setting, but chloride ions lead to corrosion of steel rebar, so it should not be used in reinforced concrete. 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 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.
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.
CaCl2 acts as flux material (decreasing melting point) in the Davy process for the industrial production of Sodium metal, through the electrolysis of molten NaCl.
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 can act as an irritant by desiccating moist skin. Solid calcium chloride dissolves exothermically, and burns can result in the mouth and esophagus if it is ingested. Ingestion of concentrated solutions or solid products may cause gastrointestinal irritation or ulceration.
Other possible side effects of taking calcium chloride include:
- A chalky taste in the mouth
- Hot flushes
- Lowered blood pressure
- Loss of appetite
- Feeling sick (nausea)
- Being sick (vomiting)
- Stomach pain
- Feeling weak
- Mental disturbances
- Extreme thirst
- Passing a large amount of urine
- Bone pain
- Kidney stones
- Irregular heart beat
Any of these may be a sign of overly high calcium blood levels (hypercalcemia).
Calcium chloride salts also tend to contain a small amount of metals, especially aluminium. Over time these metals can accumulate in the body and have a toxic effect.
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- "CPG 7117.02". FDA Compliance Articles. US Food and Drug Administration. March 1995. Retrieved 3 December 2007.
- "Dust: Don't Eat It! Control It!". Road Management & Engineering Journal. US Roads (TranSafety Inc.). 1 June 1998. Retrieved 9 August 2006.
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- "Agricultural Tire Hydroinflation". www.firestoneag.com. Firestone Tires. December 2007. Retrieved 3 December 2007.
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- 7 CFR § 205.602
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- Jana, K.; Samanta, P.K. (2011). "Clinical evaluation of non-surgical sterilization of male cats with single intra-testicular injection of calcium chloride". BMC Vet Res. 7: 39. doi:10.1186/1746-6148-7-39. PMID 21774835.
- "Accelerating Concrete Set Time". Federal Highway Administration. 1 June 1999. Retrieved 16 January 2007.
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|Wikimedia Commons has media related to Calcium chloride.|
- International Chemical Safety Card 1184
- Product and Application Information (Formerly Dow Chemical Calcium Chloride division)
- Report on steel corrosion by chloride including CaCl2
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- Calcium chloride, Anhydrous MSDS