Calcium chloride

Calcium chloride is an ionic compound of calcium and chlorine. It is highly soluble in water and it is deliquescent. It is a salt that is solid at room temperature, and it behaves as a typical ionic halide. It has several common applications such as brine for refrigeration plants, ice and dust control on roads, and in cement. It can be produced directly from limestone, but large amounts are also produced as a by-product of the Solvay process. Because of its hygroscopic nature, it must be kept in tightly-sealed containers.

Chemical properties
Calcium chloride can serve as a source of calcium ions in solution, for instance for precipitation because many calcium compounds are insoluble:

3 CaCl2(aq) +  2 potassium phosphate|K3PO4(aq)  →  Ca3(PO4)2(s)  +  6 KCl(aq)

Molten CaCl2 can be electrolysed to give calcium metal:

CaCl2(l) →  Ca(s)  +  Cl2(g)

Preparation
Calcium chloride is a by-product of the Solvay process used for the manufacture of sodium carbonate. It can also be produced by the action of hydrochloric acid on calcium carbonate.

CaCO3(s) +  2 HCl →  CaCl2(aq)  +  H2O(l)  +  CO2(g)

Uses
Millions of tonnes of calcium chloride are made each year in the US alone, and it has a variety of applications:


 * Aqueous Calcium Chloride is used in genetic transformation of cells by increasing the cell membrane permeability. This allows DNA fragments to enter the cell more readily.


 * It is used in Smartwater and some sports drinks as an Electrolyte


 * It is used in Emergency Medicine to treat Calcium Channel Blocker toxicity with overdoses of drugs such as Cardizem. It is also used to treat certain electrolyte imbalances along with Calcium Gluconate.


 * It is also used to induce competence for DNA uptake in experiments involving uptake of DNA from outside the cell

Precautions
Calcium chloride is an irritant; wear gloves and goggles to protect hands and eyes; avoid inhalation.

Although calcium chloride is relatively safe to handle, care should be taken that it is not ingested. Calcium chloride reacts exothermically with water and can burn the mouth and esophagus.

General references

 * Handbook of Chemistry and Physics, 71st edition, CRC Press, Ann Arbor, Michigan, 1990.
 * Handbook of Chemistry and Physics, 71st edition, CRC Press, Ann Arbor, Michigan, 1990.