Definition:

A chemical substance composed of chlorine and calcium, the chemical formula is CaCl2. Slightly bitter.

Physical and chemical properties:

Physical properties

Colorless cubic crystals, white or off-white, granular, honeycomb block, spherical, irregular granular, powder. Slightly toxic, odorless, slightly bitter taste. It is highly hygroscopic and easily deliquescent when exposed to the air. It is easily soluble in water, and the solubility is 74.5 g/100g water at 20°C. At the same time, it emits a lot of heat (the dissolution enthalpy of calcium chloride is -176.2cal/g), and its aqueous solution is slightly acidic. Easily soluble in a variety of polar and protic solvents, solubility in the following solvents at 20°C (g/100mL solvent): methanol: 29.2, absolute ethanol: 25.8, n-propanol: 15.8, n-butanol: 25.0, N-pentanol: 11.5, ethylene glycol: 21.6 (25°C), formic acid: 43.1, acetic acid: 15.0 (30°C), hydrazine: 16.0. But in dipolar solvents and low polarity solvents, such as ether, tetrahydrofuran, etc., it is only slightly or insoluble. It reacts with ammonia or alcohol to generate CaCl2•8NH3 and CaCl2•4C2H5OH complexes respectively. At low temperature, the solution crystallizes and precipitates as hexahydrate. When gradually heated to 30℃, it will dissolve in its own crystal water. Continue to heat and gradually lose water. When it reaches 200℃, it will become dihydrate, and then heated to 260℃. White porous anhydrous calcium chloride. Part of the hydrolysis reaction occurs during the heating and dehydration of calcium chloride hydrate, so the product often contains a small amount of CaO impurities.

Chemical nature

The pH value of 5% aqueous solution is 4.5～9.2. The 1.7% aqueous solution is isotonic with serum. This product is made with calcium carbonate and hydrochloric acid as raw materials, and is an antidote for magnesium poisoning. [3] Calcium ions can form insoluble calcium fluoride with fluoride, which is used for fluorosis rescue.

Chemical reaction equation

Calcium chloride with greater solubility can undergo a metathesis reaction to form a precipitate with less solubility:

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

CaCl2(aq) + K2SO4(aq) →CaSO4(s) + 2 KCl (aq)

CaCl2(aq) + 2 KOH(aq) →Ca(OH)2(s) + 2 KCl (aq)

CaCl2(aq) + K2CO3(aq) →CaCO3(s) + 2 KCl (aq)

CaCl2(aq) + 2 KF(aq) →CaF2(s) + 2 KCl (aq)

Pure calcium can be obtained after calcium chloride electrolysis:

CaCl2 →Ca(s) + Cl2(g) [4]

other

1. The reaction of titanium and calcium chloride at high temperature is solid, and the temperature is about 1100℃

The metal activity of calcium is stronger than that of titanium, so titanium will not replace the calcium in calcium chloride at high temperatures; the two substances cannot be combined at high temperatures.

2. The pungent gas produced by putting "sodium metabisulfite" in water together with "anhydrous calcium chloride"

The gas released is SO2. Regardless of whether there is anhydrous calcium chloride or not, sodium metabisulfite itself has a pungent odor. After being dissolved in water, it will release a small amount of SO2 due to hydrolysis. It does not react chemically with calcium chloride, unless the two solids are mixed and a very small amount of water is added. On the one hand, sodium metabisulfite is hydrolyzed, and on the other hand, CaCl2 combines with water to form crystals, so that it is possible to release more SO2. If they are mixed with each other in a dilute solution state, then the effect is not big.

3. The reaction product of solid calcium chloride and oxygen

Solid calcium chloride does not react with oxygen, so it cannot produce any other substances. Solid calcium chloride, liquid calcium chloride or gaseous calcium chloride (if it exists in these states) do not react with oxygen.

Application areas:

Industrial applications

1. Used as a multi-purpose desiccant, such as drying of nitrogen, oxygen, hydrogen, hydrogen chloride, sulfur dioxide and other gases. Used as a dehydrating agent in the production of alcohols, esters, ethers and acrylic resins. Calcium chloride aqueous solution is an important refrigerant for refrigerators and ice making. It can accelerate the hardening of concrete and increase the cold resistance of construction mortar. It is an excellent construction antifreeze. Used as an anti-fogging agent in ports, dust collectors on roads, and fabric fire retardants. Used as a protective and refining agent for aluminum and magnesium metallurgy. It is a precipitant for the production of lake pigments. Used for waste paper processing and deinking. It is the raw material for the production of calcium salt.

2. Chelating agent; curing agent; calcium enhancer; refrigerant for freezing; desiccant; anticaking agent; microbial inhibitor; pickling agent; tissue improver.

3. Used as a desiccant, road dust collector, antifogging agent, fabric fire retardant, food preservative and used to make calcium salt

4. Used as lubricant additive

5. Used as analytical reagent

6. Mainly used for the treatment of tetany, urticaria, exudative edema, intestinal and ureteric colic, magnesium poisoning, etc. caused by blood calcium reduction

7. Used as calcium fortifier, curing agent, chelating agent and desiccant in the food industry.

8. It can increase the permeability of the bacterial cell wall.

Medical use

Indications:

1. This product can be used for intestinal colic.

2. It can be used for itchy skin diseases.

3. Used to rescue magnesium salt poisoning.

4. For vitamin D deficiency rickets, rickets, and calcium supplementation for pregnant and lactating women.

5. Treatment of calcium deficiency, acute hypocalcemia, alkalosis and hypoparathyroidism caused by tetany, vitamin D deficiency, etc.;

6. Allergic diseases;

7. Rescue in case of magnesium poisoning;

8. Rescue of fluorosis;

9. It is used during cardiac resuscitation, such as the rescue of abnormal cardiac function caused by hyperkalemia, hypocalcemia, or calcium channel block.

10. Calcium chloride solution can induce the polymerization of actin monomers, and the critical concentration of actin monomers to start polymerization is inversely related to the concentration of calcium chloride solution. The specific mechanism of actin induced polymerization is related to the binding of calcium ions to multiple specific parts of the protein

5. Dosage for children: The therapeutic dose is 25mg/kg (6.8mg calcium) in hypocalcemia, intravenously instilled slowly.

In biological and medical research, calcium chloride is widely used in the preparation of buffers required for biomedical experiments. For example, when researching a new activator for potassium ion channel complexes, CaCl2 is added to prepare the separated eggs. ND96 stock solution of mother cells; CaCl2 was used for brain slice preparation experiments when studying the function of guanylate cyclase C on midbrain dopamine neurons; when studying fluororiboswitches used to resist fluorine toxicity in bacteria and archaea Carry out tandem labeling experiments with 1mmol/L CaCl2.

In the process of introducing the target gene into the recipient cell, calcium chloride can be used to increase the permeability of the recipient cell membrane, making it easier to introduce the plasmid. This method was developed by geneticist Stanley Norman Cohen of Stanford University. Discovered in 1972 when studying E. coli.

Intravenous injection of 10% calcium chloride solution can be used for the treatment of hypocalcemia, and calcium chloride can also be used for the treatment of magnesium poisoning. Through electrocardiogram measurement, it is found that injection of calcium chloride solution can combat cardiotoxicity. In the case of high serum potassium concentration caused by hyperkalemia, calcium chloride can protect the myocardium and prevent arrhythmia. Calcium chloride, as a stock medicine in emergency rooms in American hospitals, can be used to quickly treat calcium channel blocker poisoning and caused by hydrofluoric acid Poisoning, but has no effective detoxification effect on poisoning caused by black widow spider bites. Calcium chloride and sodium bromide injection is approved by the State Food and Drug Administration as a water and electrolyte regulator in China.

Desiccant

Granular anhydrous calcium chloride is often used as a desiccant to fill the drying tube, and macroalgae (or seaweed ash) dried with calcium chloride can be used for the production of soda ash. Some household dehumidifiers use calcium chloride to absorb moisture in the air. Calcium chloride can also be used as a desiccant or dehydrating agent for gases and organic liquids. Because calcium chloride is neutral, it can dry acidic or alkaline gases and organic liquids. It can also be used in the laboratory to produce small amounts of gases such as nitrogen, oxygen, hydrogen, hydrogen chloride, sulfur dioxide, carbon dioxide, nitrogen dioxide, etc. Dry these produced gases. But it cannot be used to dry ethanol and ammonia, because ethanol and ammonia will react with calcium chloride to form alcohol compounds CaCl2•4C2H5OH and ammonia compounds CaCl2•8NH3, respectively. Anhydrous calcium chloride can also be made into household products and used as an air moisture absorbent. Anhydrous calcium chloride as a water absorbent has been approved by the FDA for bandaging first aid. Its role is to ensure the dryness of the wound.

Spread the anhydrous calcium chloride on the sand and gravel road, and use the hygroscopicity of the anhydrous calcium chloride to condense the moisture in the air when the air humidity is lower than the dew point to keep the road surface moist, thereby controlling the dust on the road Raised.

Deicer and cooling bath

Calcium chloride can lower the freezing point of water. Spreading calcium chloride hydrate on the road can prevent freezing and deicing and melting snow, but the salt water after melting ice and snow will destroy the soil and vegetation along the road and deteriorate the concrete of the road.

Calcium chloride solution can also be mixed with dry ice to prepare a low temperature cooling bath. Dry ice sticks were added to the brine solution in batches until ice cubes appeared in the system. The stable temperature of the cooling bath that can be maintained by different types and concentrations of salt solutions will vary. Generally, calcium chloride is commonly used as the salt raw material, and the required stable temperature is obtained by adjusting the concentration, not only because calcium chloride is cheap and easy to obtain, but also because of the eutectic temperature of the calcium chloride solution (that is, the solution is completely condensed to form granular ice The temperature of the salt particles is quite low, reaching -51.0°C, which makes the adjustable temperature range from 0°C to -51°C. This method can be implemented in a Dewar flask that has a thermal insulation effect. It can also be used in general plastic containers to hold the cooling bath when the volume of the Dewar flask is limited and more salt solution is required. The maintenance is also relatively stable.

food

As a food ingredient, calcium chloride can act as a sequestering agent and a curing agent. It has been approved by the European Union as a food additive. The E code is E509. It is considered by the US Food and Drug Administration as "Generally recognized as safe" (Generally recognized as safe, abbreviated as GRAS). It is estimated that the daily intake of calcium chloride food additives per person is 160 to 345 mg.

As a curing agent, calcium chloride can be used for canned vegetables. It can also solidify soybean curd to form tofu. It can also be used as a raw material for cooking molecular cuisine to gel the surface of vegetables and fruit juices by reacting with sodium alginate to form caviar-like balls. It is added as an electrolyte to sports drinks or some soft drinks including bottled water. Because calcium chloride itself has a very strong salty taste, it can be used in the production of pickled cucumbers instead of salt without increasing the sodium content of food. Calcium chloride's ability to lower the freezing point is used to delay the freezing of caramel in chocolate bars filled with caramel.

Calcium chloride is added to the beer brewing liquid that lacks minerals, because calcium ion is one of the most influential minerals in the beer brewing process. It will affect the acidity of the wort and the effect of yeast. And calcium chloride can bring sweetness to the brewed beer.