Calcium chloride

Toxicity

Too rapid injection may produce lowering of blood pressure and cardiac syncope. Persistent hypercalcemia from overdosage of calcium is unlikely because of rapid excretion.

Description

Calcium chloride (CaCl2) is an inorganic salt used for removing water from gases and liquids, melting ice from road surfaces, maintaining a liquid layer on road surfaces to control dust, and preparing aqueous solutions with low freezing temperatures, and is a common desiccant used in the manufacture of food or chemicals.

Chemical properties

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.

Physical properties

White crystal, powder or flake; highly hygroscopic; the compound and its solutions absorb moisture from the air at various rates depending on calcium chloride concentrations, relative humidity and vapor pressure of water in the air, temperature, surface area of exposed material, and the rate of air circulation; at 40% and 95% relative humidity and 25°C, one gram anhydrous calcium chloride may absorb about 1.4 g and 17 g water, respectively.anhydrous salts melts at 772°C, while the mono-, di-, tetra- and hexahydrates decompose at 260°, 175°, 45.5° and 30°C, respectively; the anhydrous salt vaporizes at 1,935°C; highly soluble in water, moderate to high solubility in alcohol.

Occurrence

Calcium chloride may be found in nature as the mineral tachhydrite, CaCl₂?2MgCl₂?12H₂O. It also is found in other minerals. Its concentration in sea water is about 0.15%.
Calcium chloride has several industrial applications. The major applications of this compound are in deicing of roads, dust control, imparting stability to roads and buildings, and to improve traction in tractor tires. It is mixed with ice to make freezing mixtures. Hexahydrate mixed with crushed ice can lower the temperature of the cooling bath to below -50°C. It also is used as a desiccant for dehydrating gases and liquids. It is added to cement in various proportions to manufacture different types of concrete. Other uses are in adhesives, to lower gel temperatures, and as a calcium source in liquid feed supplements for dairy cattle. Also, the compound is used to control particle size development and reduce coalescence in plastics.

The Uses of Calcium chloride

1.Calcium chloride is one of the most versatile of the basic chemicals.It has several common applications such as brine for refrigeration plants, ice and dust control on roads, and in concrete.
2.Calcium chloride is also commonly used as an additive in swimming pool water as it increases the “calcium hardness” value for the water.
3.Calcium chloride is commonly used as an “electrolyte” and has an extremely salty taste, as found in sports drinks and other beverages such as Nestle bottled water.
4.Calcium chloride can be injected as intravenous therapy for the treatment of “hypocalcemia” (low serum calcium).

Background

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.

Indications

For the treatment of hypocalcemia in those conditions requiring a prompt increase in blood plasma calcium levels, for the treatment of magnesium intoxication due to overdosage of magnesium sulfate, and used to combat the deleterious effects of hyperkalemia as measured by electrocardiographic (ECG), pending correction of the increased potassium level in the extracellular fluid.

Definition

calcium chloride: A white deliquescentcompound, CaCl₂, which issoluble in water; r.d. 2.15; m.p.782°C; b.p. >1600°C. There are anumber of hydrated forms, includingthe monohydrate, CaCl₂.H₂O, the dihydrate,CaCl₂.2H₂O (r.d. 0.84), andthe hexahydrate, CaCl₂.6H₂O (trigonal;r.d. 1.71; the hexahydrate loses4H₂O at 30°C and the remaining2H₂O at 200°C). Large quantities of itare formed as a byproduct of theSolvay process and it can be preparedby dissolving calcium carbonateor calcium oxide in hydrochloricacid. Crystals of the anhydrous saltcan only be obtained if the hydratedsalt is heated in a stream of hydrogenchloride. Solid calcium chloride isused in mines and on roads to reducedust problems, whilst the molten saltis the electrolyte in the extraction ofcalcium. An aqueous solution of calciumchloride is used in refrigerationplants.

Preparation

Calcium chloride is obtained as a by-product in the manufacture of sodium carbonate (soda ash) by ammonia-soda (Solvay) process. The process involves the reaction of sodium chloride with calcium carbonate and ammonia. Calcium chloride is currently produced in bulk amounts by evaporation of natural underground brines. In the laboratory, calcium chloride can be prepared by treating limestone with hydrochloric acid followed by evaporation of solution to obtain crystals. The crystals are dehydrated to obtain anhydrous salt. Calcium oxide or hydroxide may be used instead of carbonate.

Air & Water Reactions

Deliquescent. Water soluble. Adding Calcium chloride to hot water caused violent boiling, [MCA Case History No. 69].

Reactivity Profile

Bromine trifluoride rapidly attacks the following salts: barium chloride, cadmium chloride, Calcium chloride, cesium chloride, lithium chloride, silver chloride, rubidium chloride, potassium bromide, potassium chloride, potassium iodide, rhodium tetrabromide, sodium bromide, sodium chloride, and sodium iodide [Mellor 2 Supp. 1:164, 165 1956]. Long term exposure of Calcium chloride solution upon a zinc coated galvanized iron vessel caused slow evolution of hydrogen which ignited and exploded [Bretherick, 5th Ed., 1995].

Health Hazard

Inhalation causes irritation of nose and throat. Ingestion causes irritation of mouth and stomach. Contact with eyes (particularly by dust) causes irritation and possible transient corneal injury. Contact of solid with dry skin causes mild irritation; strong solutions can cause marked irritation, even a superficial burn.

Pharmacokinetics

Calcium is the fifth most abundant element in the body and the major fraction is in the bony structure. Calcium plays important physiological roles, many of which are poorly understood. It is essential for the functional integrity of the nervous and muscular systems. It is necessary for normal cardiac function and is one of the factors that operates in the mechanisms involved in the coagulation of blood.

Toxicity

Calcium chloride is used in topical, ophthalmic, and injection preparations. The pure form of calcium chloride is toxic by intravenous, intramuscular, intraperitoneal, and subcutaneous routes, and moderately toxic by ingestion, causing stomach and heart disturbances. It is a severe eye irritant and can cause dermatitis.
LD₅₀ (mouse, IP): 0.21 g/kg
LD₅₀ (mouse, IV): 0.042 g/kg
LD₅₀ (mouse, oral): 1.94 g/kg
LD₅₀ (mouse, SC): 0.82 g/kg
LD₅₀ (rat, IM): 0.025 g/kg
LD₅₀ (rat, IP): 0.26 g/kg
LD₅₀ (rat, oral): 1.0 g/kg
LD₅₀ (rat, SC): 2.63 g/kg

Potential Exposure

Calcium chloride is used as road salt for melting snow, a drying agent in desiccators, for dehydrating organic liquids and gases, in refrigeration brines and antifreeze, as a dust-proofing agent, food additives, concrete hardening accelerator, and others. May react with strong oxidizers.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seekmedical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, getmedical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.

Metabolism

Approximately 80% of body calcium is excreted in the feces as insoluble salts; urinary excretion accounts for the remaining 20%.

Hazard

Calcium chloride can irritate the nose and throat if inhaled. Ingestion can irritate the mouth and stomach. Contact with eyes (especially dust) causes irritation and may cause transient corneal damage. Solid in contact with dry skin causes slight irritation; strong solutions cause marked irritation and even epidermal burns.

Shipping

There are no label or maximum shipping quantity requirements set by DOT.

Incompatibilities

Calcium chloride is incompatible with soluble carbonates, phosphates, sulfates, and tartrates. It reacts violently with bromine trifluoride, and a reaction with zinc releases explosive hydrogen gas. It has an exothermic reaction with water, and when heated to decomposition it emits toxic fumes of chlorine.

Regulatory Status

GRAS listed. Included in the FDA Inactive Ingredients Database (injections, ophthalmic preparations, suspensions, creams). Included in medicines licensed in the UK (eye drops; intraocular irrigation; vaccines; injection powders for reconstitution; nebulizer solution; oral suspension).