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Calcium chloride

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Calcium chloride
Structure of calcium chloride, (chlorine is green, calcium is gray)
Sample of calcium chloride
IUPAC name
Calcium chloride
Other names
Calcium(II) chloride, Calcium dichloride, E509
ATC code A12AA07
B05XA07, G04BA03
10043-52-4 N
22691-02-7 (monohydrate) N
10035-04-8 (dihydrate) N
25094-02-4 (tetrahydrate) N
7774-34-7 (hexahydrate) N
ChEMBL ChEMBL1200668 N
ChemSpider 23237 YesY
DrugBank DB01164 YesY
EC-number 233-140-8
Jmol-3D images Image
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)
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)[3]
Solubility Soluble in CH3COOH, alcohols
Insoluble in liquid NH3, DMSO, CH3COOC2H5[4]
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)[4]
Solubility in methanol 21.8 g/100 g (0 °C)
29.2 g/100 g (20 °C)
38.5 g/100 g (40 °C)[4]
Solubility in acetone 0.1 g/kg (20 °C)[4]
Solubility in pyridine 16.6 g/kg[4]
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)[4]
Crystal structure Orthorhombic (rutile, anhydrous), oP6
Tetragonal (anhydrous, > 217 °C), oP6[5]
Trigonal (hexahydrate)
Space group Pnnm, No. 58 (anhydrous)
P42/mnm, No. 136 (anhydrous, > 217 °C)[5]
Point group 2/m 2/m 2/m (anhydrous)
4/m 2/m 2/m (anhydrous, > 217 °C)[5]
Lattice constant a = 6.259 Å, b = 6.444 Å, c = 4.17 Å (anhydrous, 17 °C)[5]
Lattice constant 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]
SDS External SDS
GHS pictograms The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)[6]
GHS signal word Warning
EU Index 017-013-00-2
EU classification Irritant Xi
R-phrases R36
S-phrases S22, S24
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
1000 mg/kg (rats, oral)[7]
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 noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N verify (what isYesY/N?)
Infobox references

Calcium chloride (chemical formula CaCl2) is the ionic compound of calcium and chlorine. It is a salt that behaves as a typical ionic halide, being solid at room temperature and highly soluble in water. 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, airtight containers.


Flame test of CaCl2.

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)

Molten calcium chloride can be electrolysed to give calcium metal and chlorine gas:

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.

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).[8] A Dow Chemical Company manufacturing facility in Michigan houses about 35% of the total U.S. production capacity for calcium chloride.[9]


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 in producing sodium carbonate. Anhydrous calcium chloride has been approved by the FDA as a packaging aid to ensure dryness (CPG 7117.02).[10]

These hygroscopic properties are also applied to keep a liquid layer on the surface of the roadway, which holds dust down.[11]

Also used in salt/chemical-based dehumidifiers in domestic and other environments to adsorb dampness/moisture from the air.[12]

Deicing and freezing point depression[edit]

Bulk of CaCl2 for deicing in Japan.

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.[13] 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.[14]

Swimming pools and aquariums[edit]

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.[citation needed]

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.[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]

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. 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.[19]

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).

Animal sterilization[edit]

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.[20][21]


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.[22] The anhydrous form of calcium chloride may also be used for this purpose and can provide a measure of the moisture in concrete.[23]

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.

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.[24]

Other possible side effects of taking calcium chloride include:

  • A chalky taste in the mouth
  • Hot flashes
  • Lowered blood pressure
  • Loss of appetite
  • Feeling sick (nausea)
  • Being sick (vomiting)
  • Constipation
  • Stomach pain
  • Feeling weak
  • Mental disturbances
  • Extreme thirst
  • Passing a large amount of urine
  • Bone pain
  • Kidney stones
  • Irregular heart beat
  • Coma

Any of these may be a sign of overly high calcium blood levels (hypercalcemia).[25]

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.

See also[edit]


  1. ^ a b c d e f g h 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. ^ a b c d e f Pradyot, Patnaik (2003). Handbook of Inorganic Chemicals. The McGraw-Hill Companies, Inc. p. 162. ISBN 0-07-049439-8. 
  3. ^ Seidell, Atherton; Linke, William F. (1919). Solubilities of Inorganic and Organic Compounds (2nd ed.). New York: D. Van Nostrand Company. p. 196. 
  4. ^ a b c d e f Anatolievich, Kiper Ruslan. "cadmium chloride". Retrieved 2014-07-07. 
  5. ^ a b c d Müller, Ulrich (2006). Inorganic Structural Chemistry. (2nd ed.) (England: John Wiley & Sons Ltd.). p. 33. ISBN 978-0-470-01864-4. 
  6. ^ a b c Sigma-Aldrich Co., Calcium chloride. Retrieved on 2014-07-07.
  7. ^ Cite error: The named reference fca was invoked but never defined (see the help page).
  8. ^ Calcium Chloride SIDS Initial Assessment Profile, UNEP Publications, SIAM 15, Boston, 22–25 October 2002, page 11.
  9. ^ Calcium Chloride Chemical Profile, The Innovation Group,, printed 9 September 2005.
  10. ^ "CPG 7117.02". FDA Compliance Articles. US Food and Drug Administration. March 1995. Retrieved 3 December 2007. 
  11. ^ "Dust: Don't Eat It! Control It!". Road Management & Engineering Journal. US Roads (TranSafety Inc.). 1 June 1998. Retrieved 9 August 2006. 
  12. ^ " Keeping Things Dry". Retrieved 2014-10-23. 
  13. ^ "De-icer damaging thousands of trees on mountain passes". The Seattle Times. 19 March 2008. Retrieved 18 March 2008. 
  14. ^ "Agricultural Tire Hydroinflation". Firestone Tires. December 2007. Retrieved 3 December 2007. 
  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. ^ "Calcium chloride Prescribing Information". Hospira, Inc. November 2009. Retrieved 10 June 2011. 
  20. ^ Koger, Nov 1977, "Calcium Chloride, Practical Necrotizing Agent", Journal of the American Association of Bovine Practitioners (USA), (Nov 1977), v. 12, p. 118–119
  21. ^ 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. 
  22. ^ "Accelerating Concrete Set Time". Federal Highway Administration. 1 June 1999. Retrieved 16 January 2007. 
  23. ^ 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. 
  24. ^ "Product Safety Assessment (PSA): Calcium Chloride". Dow Chemical Company. 2 May 2006. 
  25. ^ "Calcium Chloride Possible Side Affects". 

External links[edit]