Calcium chloride

Calcium chloride (or Calcium dichloride, Calcium(II) chloride).

Chemical formula : CaCl₂ (anhydrous)
(Cl = 63,89 %, Ca = 36,11 %, )
Molar mass = 110,984 ± 0,008 g·mol^-1

The anhydrous salt is a very hygroscopic white powder.
It is deliquescent; it can accumulate enough water in its crystal lattice to form a solution.

Calcium chloride crystallizes from water to form three different hydrates:

• monohydrate (CaCl₂.H₂O), 128.999 g/mol
• dihydrate (CaCl₂.2H₂O), 147.014 g/mol
• tetrahydrate (CaCl₂.4 H₂O), 183.045 g/mol
• hexahydrate (CaCl₂.6 H₂O), 219.08 g/mol

Production.
It is mainly obtained from chalk (calcium carbonate formed).
For example it may be prepared by reacting calcium carbonate [CaCO3] and hydrochloric solution [HCl] acid:

Calcium chloride can be produced directly from limestone, but large amounts are also produced as a by product of the Solvay process.

This is a very hygroscopic material should be stored in tightly closed containers. It is prized for its exothermic qualities.
It behaves like a typical halide salt, in particular with a good electrical conductivity in the liquid state and ionic chemical bonds.

In water treatment, it is used by injection in the form of water solutions (saturated or not).

The most widely used commercial solutions are:

1. 33% or 17.7 g / L (density 1.33 - crystallization temperature - 30 ° C)
2. 42% or 34.1 g / L (density 1.41 - crystallization temperature + 18 ° C of )

Main Features :

	Anhydrous form
% CaCl2	>96 %
Volumetric mass density (20°C)	2150 kg/m3
Melting point	772°C
Solubility at 20°C	745 g/L

Solubility of anhydrous calcium chloride in water (soft) depending on the temperature (CaCl2 g / kg of H2O):

The dissolution process is exothermic and above 60 °C can be reached rapidly.
Due to its very hygroscopic nature, it can be used to dry the air, gas or other body fluids (or seeds).
When it absorbs water or water vapor of the substance to be dried, it is transformed into brine:

A formulation for water treatment.
Injection of 11.1 mg of CaCl2 in 1 liter of pure water, calcium hardness (calcium) increases by 4 mg/L of calcium (or 1°F).

Standardization.
Standard products used for the production of drinking water: French Official Bulletin - Calcium chloride

Uses.

• Food:
  • 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 and is on the 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.
• Other :
  • 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.
  • 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.

Safety.
Calcium chloride is irritating. It should be handled with gloves. It is relatively safe to handle, but it should not be ingested, it reacts exothermically with water, it can cause burning of the mouth or esophagus.

Sources : personal and Wikipedia, the free encyclopedia.

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