Calcium chloride

Calcium chloride
IUPAC name
Calcium chloride
Other names
Calcium(II) chloride, Calcium dichloride, E509
10043-52-4 YesY
22691-02-7 (monohydrate) N
10035-04-8 (dihydrate) N
25094-02-4 (tetrahydrate) N
7774-34-7 (hexahydrate) N
3D model (Jmol) Interactive image
ChEMBL ChEMBL1200668 N
ChemSpider 23237 YesY
DrugBank DB01164 YesY
ECHA InfoCard 100.030.115
EC Number 233-140-8
E number E509 (acidity regulators, ...)
PubChem 24854
RTECS number EV9800000
Molar mass 110.98 g·mol−1
Appearance White powder, hygroscopic
Odor Odorless
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)[1]
Melting point 772–775 °C (1,422–1,427 °F; 1,045–1,048 K)
260 °C (500 °F; 533 K)
monohydrate, decomposes
175 °C (347 °F; 448 K)
dihydrate, decomposes
45.5 °C (113.9 °F; 318.6 K)
tetrahydrate, decomposes[2]
30 °C (86 °F; 303 K)
hexahydrate, decomposes[1]
Boiling point 1,935 °C (3,515 °F; 2,208 K) anhydrous[1]
74.5 g/100 mL (20 °C)[3]
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)[1]
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)[4]
Solubility Soluble in CH3COOH, alcohols
Insoluble in liquid NH3, DMSO, CH3COOC2H5[5]
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)[5]
Solubility in methanol 21.8 g/100 g (0 °C)
29.2 g/100 g (20 °C)
38.5 g/100 g (40 °C)[5]
Solubility in acetone 0.1 g/kg (20 °C)[5]
Solubility in pyridine 16.6 g/kg[5]
Acidity (pKa) 8–9 (anhydrous)
6.5–8.0 (hexahydrate)
−5.47·10−5 cm3/mol[1]
Viscosity 3.34 cP (787 °C)
1.44 cP (967 °C)[5]
Orthorhombic (rutile, anhydrous), oP6
Tetragonal (anhydrous, > 217 °C), oP6[6]
Trigonal (hexahydrate)
Pnnm, No. 58 (anhydrous)
P42/mnm, No. 136 (anhydrous, > 217 °C)[6]
2/m 2/m 2/m (anhydrous)
4/m 2/m 2/m (anhydrous, > 217 °C)[6]
a = 6.259 Å, b = 6.444 Å, c = 4.17 Å (anhydrous, 17 °C)[6]
α = 90°, β = 90°, γ = 90°
Octahedral (Ca2+, anhydrous)
72.89 J/mol·K (anhydrous)[1]
106.23 J/mol·K (monohydrate)
172.92 J/mol·K (dihydrate)
251.17 J/mol·K (tetrahydrate)
300.7 J/mol·K (hexahydrate)[2]
108.4 J/mol·K[1][2]
−795.42 kJ/mol (anhydrous)[1]
−1110.98 kJ/mol (monohydrate)
−1403.98 kJ/mol (dihydrate)
−2009.99 kJ/mol (tetrahydrate)
− 2608.01 kJ/mol (hexahydrate)[2]
−748.81 kJ/mol[1][2]
A12AA07 (WHO) B05XA07 (WHO), G04BA03 (WHO)
Safety data sheet See: data page
GHS pictograms [7]
GHS signal word Warning
R-phrases R36
S-phrases S22, S24
NFPA 704
Lethal dose or concentration (LD, LC):
1000 mg/kg (rats, oral)[8]
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
Refractive index (n),
Dielectric constantr), etc.
Phase behaviour
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Calcium chloride is an inorganic compound, a salt with the chemical formula CaCl2. It is a colorless crystalline solid at room temperature, highly soluble in water.

Calcium chloride is commonly encountered as a hydrated solid with generic formula CaCl2(H2O)x, where x = 0, 1, 2, 4, and 6. These compounds are mainly used for deicing and dust control. Because the anhydrous salt is hygroscopic, it is used as a desiccant.[9]


Flame test of CaCl2.

Calcium chloride dissolves in water to afford chloride and the aquo complex [Ca(H2O)6]2+. 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 sources to give solid precipitate of calcium phosphate:

3 CaCl2 + 2 PO3−
→ Ca3(PO4)2 + 6 Cl

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 metal and chlorine gas.

CaCl2 → Ca + Cl2


In much of the world, calcium chloride is derived from limestone as a by-product of the Solvay process:[9] North American consumption in 2002 was 1,687,000 tons (3.37 billion pounds).[10]

2 NaCl + CaCO3 → Na2CO3 + CaCl2

In the US, most of calcium chloride is obtained by purification from brine. A Dow Chemical Company manufacturing facility in Michigan houses about 35% of the total U.S. production capacity for calcium chloride.[11]

Structure of the polymeric [Ca(H2O)6]2+ center in crystalline calcium chloride hexahydrate, illustrating the high coordination number typical for calcium complexes.


Calcium chloride occurs as the rare evaporite minerals sinjarite (dihydrate) and antarcticite (hexahydrate). The related minerals chlorocalcite (potassium calcium chloride, KCaCl3) and tachyhydrite (calcium magnesium chloride, CaMg2Cl6·12H2O) are also very rare.


Deicing and freezing point depression

Bulk of CaCl2 for deicing in Japan.

By depressing the freezing point of water, calcium chloride is used to prevent ice formation and is used to deice. This application consumes the greatest amount of calcium chloride. Calcium chloride is relatively harmless to plants and soil. As a deicing agent, it is more effective at lower temperatures than sodium chloride. When distributed for this use, it usually takes the form of small, white spheres 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.[12]

Also used in salt/chemical-based dehumidifiers in domestic and other environments to adsorb dampness/moisture from the air.[13]

Road surfacing

Calcium chloride was sprayed on this road to prevent weathering, giving it a wet appearance even in dry weather.

The second largest application of calcium chloride exploits its hygroscopic properties and the tackiness of its hydrates. A concentrated solution keeps a liquid layer on the surface of dirt roads, which suppresses formation of dust. It keeps the finer dust particles on the road, providing a cushioning layer. If these are allowed to blow away, the larger 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%[14]

Water treatment

Calcium chloride is used to increase the water hardness in swimming pools. This process 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.


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.[15] Its use in organic crop production is generally prohibited under US National Organic Program's National List of Allowed and Prohibited Substances.[16] The average intake of calcium chloride as food additives has been estimated to be 160–345 mg/day for individuals.[17] 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 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.[18] 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.

In cheesemaking, calcium chloride is sometimes added to processed (pasteurized/homogenized) milk to restore the natural balance between calcium and protein in casein for the purposes of making cheeses, such as brie, Pélardon and Stilton. By adding calcium chloride to the milk before adding the coagulant, calcium levels are restored. Also, it is frequently added to sliced apples to maintain texture.

Drying tubes are frequently packed with calcium chloride. Kelp is dried with calcium chloride for use in producing sodium carbonate. Anhydrous calcium chloride has been approved by the FDA as a packaging aid to ensure dryness (CPG 7117.02).[19]


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.[20]

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).

Miscellaneous applications

Calcium chloride is used in concrete mixes to accelerate (speed up) the initial setting, but chloride ions lead to corrosion of steel rebar, so it should not be used in reinforced concrete.[21] The anhydrous form of calcium chloride may also be used for this purpose and can provide a measure of the moisture in concrete.[22]

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.

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.

Animal sterilization

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.[23][24]


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.[25]

Consumption of calcium chloride can lead to hypercalcemia.[26]

See also


  1. 1 2 3 4 5 6 7 8 9 Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4200-9084-0.
  2. 1 2 3 4 5 6 Pradyot, Patnaik (2003). Handbook of Inorganic Chemicals. The McGraw-Hill Companies, Inc. p. 162. ISBN 0-07-049439-8.
  3. "CALCIUM CHLORIDE (ANHYDROUS)". ICSC. International Programme on Chemical Safety and the European Commission.
  4. Seidell, Atherton; Linke, William F. (1919). Solubilities of Inorganic and Organic Compounds (2nd ed.). New York: D. Van Nostrand Company. p. 196.
  5. 1 2 3 4 5 6 Anatolievich, Kiper Ruslan. "Properties of substance: calcium chloride". Retrieved 2014-07-07.
  6. 1 2 3 4 Müller, Ulrich (2006). Inorganic Structural Chemistry. (2nd ed.). England: John Wiley & Sons Ltd. p. 33. ISBN 978-0-470-01864-4.
  7. 1 2 3 Sigma-Aldrich Co., Calcium chloride. Retrieved on 2014-07-07.
  8. 1 2 "MSDS of Calcium chloride". Fisher Scientific. Retrieved 2014-07-07.
  9. 1 2 Robert Kemp, Suzanne E. Keegan "Calcium Chloride" in Ullmann's Encyclopedia of Industrial Chemistry 2000, Wiley-VCH, Weinheim. doi:10.1002/14356007.a04_547
  10. Calcium Chloride SIDS Initial Assessment Profile, UNEP Publications, SIAM 15, Boston, 22–25 October 2002, page 11.
  11. Calcium Chloride Chemical Profile, The Innovation Group,, printed 9 September 2005.
  12. "Agricultural Tire Hydroinflation". Firestone Tires. December 2007. Retrieved 3 December 2007.
  13. " Keeping Things Dry". Retrieved 2014-10-23.
  14. "Dust: Don't Eat It! Control It!". Road Management & Engineering Journal. US Roads (TranSafety Inc.). 1 June 1998. Retrieved 9 August 2006.
  15. 21 CFR § 184.1193
  16. 7 CFR § 205.602
  17. Calcium Chloride SIDS Initial Assessment Profile, UNEP Publications, SIAM 15, Boston, 22–25 October 2002, pp. 13–14.
  18. "Apple Caviar Technique". StarChefs Studio. April 2004. Retrieved 9 August 2006.
  19. "CPG 7117.02". FDA Compliance Articles. US Food and Drug Administration. March 1995. Retrieved 3 December 2007.
  20. "Calcium chloride Prescribing Information". Hospira, Inc. November 2009. Retrieved 10 June 2011.
  21. "Accelerating Concrete Set Time". Federal Highway Administration. 1 June 1999. Retrieved 16 January 2007.
  22. National Research Council (U.S.). Building Research Institute (1962). Adhesives in Building: Selection and Field Application; Pressure-sensitive Tapes. National Academy of Science-National Research Council. pp. 24–5.
  23. Koger, Nov 1977, "Calcium Chloride, Practical Necrotizing Agent", Journal of the American Association of Bovine Practitioners (USA), (Nov 1977), v. 12, p. 118–119
  24. 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.
  25. "Product Safety Assessment (PSA): Calcium Chloride". Dow Chemical Company. 2 May 2006.
  26. "Calcium Chloride Possible Side Affects".
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