471-34-1 Usage
Description
Calcium carbonate is a naturally occurring white solid compound with the chemical formula CaCO3. It is found in various forms such as limestone, marble, chalk, and coral. It is sparingly soluble in water and decomposes on heating to give calcium oxide and carbon dioxide.
Uses
Used in Building Materials Industry:
Calcium carbonate is used as a primary raw material to produce cement, mortars, plasters, refractories, and glass.
Used in Construction:
Most limestone, a form of calcium carbonate, is used as a construction material.
Used in Papermaking:
Calcium carbonate is used as a filler and coating pigment to whiten paper, replace more expensive optical brightening agents and wood pulp fiber, and help control the pH in an alkaline range.
Used in Plastics Production:
It is used in the production of polyvinyl chloride (PVC), thermoset polyesters, and polyolefins as an optical brightener, whitening agent, and to increase strength and absorb heat during exothermic processes.
Used in Paints and Coatings:
Calcium carbonate is an additive to improve particle size distribution, opacity control, weather resistance, pH control, and anticorrosion.
Used in Agriculture:
It is used to neutralize acidic soils and mitigate the effects of acid precipitation on water bodies.
Used in Environmental Applications:
Calcium carbonate is used for gas desulfurization in scrubbers to reduce sulfur emissions from air pollution sources.
Used in Food Industry:
Calcium carbonate is used as an anticaking agent and dough strengthener, as a filler in baking powder, for calcium enrichment, as a mild buffering agent in doughs, as a source of calcium ions in dry mix desserts, and as a neutralizer in antacids.
Used in Textiles, Adhesives, Sealants, and Cosmetics:
Various grades of precipitated calcium carbonate are used in these products due to their fine particles, greater purity, and more uniform size.
Used in Chemical Industry:
Calcium carbonate is used to produce quicklime, hydrated lime, and a number of calcium compounds. It is also used in the Solvay process.
Used in Agricultural Lime:
Calcium carbonate is the active ingredient in agricultural lime, which is used to neutralize soil acidity in a process called liming.
Used in Laboratory:
Calcium carbonate is precipitated from limewater by carbon dioxide and is used in making lime (calcium oxide).
Production Methods
Calcium carbonate is obtained from natural limestone deposits. The purified compound, known as precipitated calcium carbonate, is synthesized from limestone. Limestone is calcined to calcium oxide and carbon dioxide in a kiln. The products are recombined after purification. Calcium oxide is hydrated with water to give a slurry called milk of lime, which is then carbonated by bubbling CO2 through it. The reactions involved in the process are as follows:
CaCO3 CaO + CO2
CaO + H2O Ca(OH)2
Ca(OH)2+ CO2→CaCO3+ H2O
The crystal sizes required for various commercial applications may be controlled by temperature, pH, concentrations, and mixing rate.
Calcium carbonate also may be precipitated by mixing solutions of calcium chloride and sodium carbonate.
Preparation
Calcium carbonate may also be produced by
mixing solutions of calcium chloride and sodium
carbonate. In some cases, the presence of sodium is
objectionable so that the ammonium carbonate salt is
preferable.
Reactions
Calcium carbonate decomposes to calcium oxide and CO2 on heating. Treatment with dilute mineral acids produces corresponding calcium salts with liberation of CO2:
CaCO3+ 2HCl →CaCl2+ H2O + CO2
In the presence of CO2 it dissolves in water with the formation of bicarbonate:
CaCO3+ H2O + CO2→Ca2++ 2HCO3 ˉ
It is reduced to calcium carbide when heated with coke or anthracite in an electric furnace:
2CaCO3+ 5C→(high temperature)→2CaC2+ 3CO2
Flammability and Explosibility
Notclassified
Pharmaceutical Applications
Calcium carbonate (CaCO3) can be found in clinical applications such as antacids, but not that an excessive intake can be hazardous.
A variety of calcium salts are used for clinical application, including calcium carbonate, calcium chloride,
calcium phosphate, calcium lactate, calcium aspartate and calcium gluconate. Calcium carbonate is the most
common and least expensive calcium supplement. It can be difficult to digest and may cause gas in some
people because of the reaction of stomach HCl with the carbonate and the subsequent production of CO2.
Calcium carbonate is recommended to be taken with food, and the absorption rate in the intestine depends
on the pH levels. Taking magnesium salts with it can help prevent constipation. Calcium carbonate consists
of 40% Ca2+, which means that 1000 mg of the salt contains around 400 mg of Ca2+. Often, labels will only
indicate the amount of Ca2+ present in each tablet and not the amount of calcium carbonate.
Biochem/physiol Actions
Calcium carbonate is a naturally occurring compound that reduces T4 absorption and enhancess serum thyrotropin levels. It also precludes osteoporosis induced by thyrotropin-suppressive doses of levothyroxine in postmenopausal women. Additionally, it reduces diarrhea in individuals with protease inhibitor-induced HIV-infection.
Clinical Use
Phosphate binding agent
Calcium supplement
Safety
Calcium carbonate is mainly used in oral pharmaceutical formulations
and is generally regarded as a nontoxic material. However,
calcium carbonate administered orally may cause constipation and
flatulence. Consumption of large quantities (4–60 g daily) may also
result in hypercalcemia or renal impairment. Therapeutically, oral
doses of up to about 1.5 g are employed as an antacid. In the
treatment of hyperphosphatemia in patients with chronic renal
failure, oral daily doses of 2.5–17 g have been used. Calcium
carbonate may interfere with the absorption of other drugs from the
gastrointestinal tract if administered concomitantly.
LD50 (rat, oral): 6.45 g/kg
Metabolism
Under the influence of gastric acid, any residual carbonate
will be converted to carbon dioxide and water.
Any unbound calcium not involved in the binding
of phosphate will be variable and may be absorbed.
Calcium is absorbed mainly from the small intestine by
active transport and passive diffusion. About one-third
of ingested calcium is absorbed although this can vary
depending upon dietary factors and the state of the small
intestine. 1,25-Dihydroxycholecalciferol (calcitriol), a
metabolite of vitamin D, enhances the active phase of
absorption.
Excess calcium is mainly excreted renally. Unabsorbed
calcium is eliminated in the faeces, together with that
secreted in the bile and pancreatic juice. Minor amounts
are lost in the sweat, skin, hair, and nails.
storage
Calcium carbonate is stable and should be stored in a well-closed
container in a cool, dry place.
Incompatibilities
Incompatible with acids and ammonium salts.
Regulatory Status
GRAS listed. Accepted for use as a food additive in Europe.
Included in the FDA Inactive Ingredients Database (buccal chewing
gum, oral capsules and tablets; otic solutions; respiratory inhalation
solutions). Included in nonparenteral medicines licensed in the UK.
Included in the Canadian List of Acceptable Non-medicinal
Ingredients.
Check Digit Verification of cas no
The CAS Registry Mumber 471-34-1 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 4,7 and 1 respectively; the second part has 2 digits, 3 and 4 respectively.
Calculate Digit Verification of CAS Registry Number 471-34:
(5*4)+(4*7)+(3*1)+(2*3)+(1*4)=61
61 % 10 = 1
So 471-34-1 is a valid CAS Registry Number.
InChI:InChI=1/CH2O3.Ca.2H/c2-1(3)4;;;/h(H2,2,3,4);;;/p-2/rCH2O3.CaH2/c2-1(3)4;/h(H2,2,3,4);1H2/p-2
