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Calcium Chloride

Calcium chloride is an inorganic, white crystalline salts which is highly soluble in water. It can be created by neutralising hydrochloric acid with calcium hydroxide or as a by-product from the Solvay process to generating Sodium Carbonate from the reaction of Sodium Chloride brine with Calcium Carbonate.

Synonyms
Calcium Dichloride, E509
Chemical Formula
CaCl2
CAS Number
10043-52-4 (anhydrous), 10035-04-8 (dihydrate), 25094-02-4 (tetrahydrate), 7774-34-7 (hexahydrate)

Characteristics

Molar Weight
110.98 g/mol
Melting Point
175°C (dihydrate)
Density
1.85 g/cm³ (dihydrate)
Forms
White, Liquid (clear), Crystalline, Solid

Uses and Applications

Key applications

  • Beverage processing
  • Food additive
  • Water treatment
  • De-icer
  • Pulp and paper
  • Agricultural
  • Personal care
  • Cosmetic products

General information

Calcium chloride is a chloride of the alkaline earth metal calcium. It has the molecular formula CaCl2. Calcium chloride is the calcium salt of hydrochloric acid.
In nature, calcium chloride is found dissolved in brines. Industrially, calcium chloride is produced from hydrochloric acid and calcium carbonate. In addition, the substance is a waste product in soda production according to the Solvay process: It is formed when ammonia is recovered from the ammonium chloride produced in the process.
Properties of calcium chloride
Calcium chloride is a salt composed of calcium and chlorine. Because of the large difference in electronegativity, calcium and chlorine are present as ions - thus the bonding takes place via electrostatic interactions.
The calcium part of the salt has the oxidation state +2, chlorine has the oxidation state -1. In its pure form, calcium chloride forms colourless and odourless crystals. In its anhydrous state, it is strongly hygroscopic, i.e. it absorbs moisture from the environment. In doing so, it forms a hydrate complex. Anhydrous calcium chloride dissolves in water with the formation of heat, so this is an exothermic reaction.
This forms a hexahydrate, which can be obtained from the solution by crystallisation. If the calcium chloride hexahydrate is heated, it melts at about 30 °C in its own water of crystallisation. If more heat is added, the dihydrate is formed, later the monohydrate. If the temperature is raised further to over 200 °C, the water of crystallisation is completely released - anhydrous calcium chloride is formed again. Hydrous calcium chloride also dissolves in water, but in an endothermic reaction - a strong cooling occurs.
Calcium chloride is highly soluble in ethanol.
Female chemist checking the liquid in a test laboratory bottle in the application kitchen, Essen, Germany

Calcium chloride in the laboratory

Because of its hygroscopicity, anhydrous calcium chloride is an important drying agent in the laboratory. For example, it is used in the desiccator, a chemical laboratory device used to dry solid chemical substances in analytical and preparative chemistry.
In technical chemistry, anhydrous calcium chloride is used to dry gases and liquids. Calcium chloride is also used as a hexahydrate in the production of refrigeration mixtures: If ice is mixed with calcium chloride, the temperature drops to as low as -50 °C.
Construction worker plastering cement on concrete block wall

Calcium chloride in the construction industry

Anhydrous calcium chloride is used in the construction industry to bind sand and dust on unpaved roads. If the surface of a road appears wet despite being dry, the road has probably been consolidated with calcium chloride. Since salt is highly hygroscopic, a concentrated calcium chloride solution applied to the road absorbs moisture and thus reduces the removal of road dust - the road surface needs to be levelled less often and the surface renewed less frequently.
Another application of anhydrous calcium chloride in the construction industry is the drying of living spaces. It is also used as a dust binder on construction sites, in blasting work and mining, and as a road salt.

Calcium chloride in the food industry

In the food industry, calcium chloride is listed under the name E 509. The salt is a common additive in many foods. It functions as a flavour enhancer, stabiliser (for example in drinking water treatment) and complexing agent (firming agent). The daily intake is estimated at 160-345 mg, a maximum recommended dose has not been determined. In the food production of cheese and milk products, calcium chloride causes the coagulation of proteins, as it forms a solid compound with proteins and pectins. With the aim of improving the properties of the precipitated casein, calcium chloride is added to milk in some cases, for exampl, in cheese production. Calcium chloride also stabilises tofu - in this case the soy mass. The salt is also used in the production of artificial caviar.
It is also added to canned vegetables, canned fruit and jams as a firming agent. Calcium chloride is also used in beer production. It influences taste and yeast growth and balances the mineral content of the brewing water. Since calcium chloride tastes salty, it can replace table salt in pickles and sour vegetables. In isotonic sports drinks, it functions as an electrolyte. Since anhydrous calcium chloride reacts with water under heat (exothermic hydration), it is also used in the heating of ready-to-drink beverages.
The surface of fruit and vegetables is also treated with calcium chloride during the growth phase. In the case of apples, this helps to prevent, among other things, the deficiency disease Stippe, which causes brown spots.
The naturally occurring salt is also found in natural mineral water.
Close up of unrecognizable mother pouring cough syrup into a dose for her small boy at home.

Calcium chloride in medicine

In the medical field, calcium chloride is used to treat calcium deficiency. Usually, patients are given a blood transfusion of red blood cell concentrates containing citrate. In addition, the salt is used as an emergency medication to treat severe hyperkalaemia.
Calcium chloride is also used to stop bleeding and as a remedy for calcium deficiency, chillblains and allergies.

Calcium chloride in biology

In molecular biology, calcium chloride increases the cell's uptake potential for DNA (transfection), as calcium ions change the permeability of the cell membrane. This creates so-called competent cells that can take up free DNA in solution, for example, to clone it - i.e. to produce identical molecules of DNA.
Other uses of calcium chloride
Calcium chloride is added to the water in concrete swimming pools to increase the water hardness. The aim is to reduce concrete erosion by dissolving calcium compounds from the concrete.
Calcium chloride is also used to increase the calcium content in aquariums with seawater.