Calcium Carbonate

Calcium carbonate (CaCO₃), a ionic compound formed through ionic bonding between calcium cations (Ca²⁺) and carbonate anions (CO₃²⁻), is widely encountered in various geological and biological contexts. It is a key component of materials such as limestone, chalk, and marble, which are extensively used in construction and sculpture. In the realm of chemistry, calcium carbonate is a vital substance utilized in various applications due to its stability and versatility. Additionally, it plays a crucial role in biology, serving as the material for the shells of marine organisms, snails, and eggs, as well as the skeletons of coral reefs.

What is Calcium Carbonate ?

Calcium carbonate is a chemical compound with the formula CaCO₃. It is a common substance found in rocks as the minerals calcite and aragonite (most notably as limestone, which contains both of those minerals) and is the main component of pearls and the shells of marine organisms, snails, and eggs. Calcium carbonate is the active ingredient in agricultural lime and is created when calcium ions in hard water react with carbonate ions to create limescale. It is medicinally used as a calcium supplement or as an antacid, but excessive consumption can be hazardous.

Chemical Names and Formulas

Property Value
Formula CaCO₃
Hill Formula CCaO₃
Name Calcium carbonate
Alternate Names Calcite, Chalk, Limestone, Marble, Pearl, Aeromatt

Common Names Of Calcium Carbonate

Common Name Description
Limestone Sedimentary rock used in building and as a primary ingredient in cement production.
Chalk Soft, white, porous form used for drawing, classroom chalk, and in climbing.
Marble Metamorphic rock formed from limestone, used in architecture and sculpture.
Calcite The most stable form of calcium carbonate, occurring naturally or as a ground powder in various industries.
Aragonite A naturally occurring polymorph of calcium carbonate, found in marine environments and used in aquariums.
Lime Refers to products derived from limestone, such as quicklime and hydrated lime, used in construction and industrial processes.
Precipitated Calcium Carbonate (PCC) Manufactured calcium carbonate produced under controlled conditions, used in the production of paper, paint, and plastics.

Structure of Calcium Carbonate

Structure of Calcium carbonate

Calcium carbonate is characterized by its unique chemical structure, represented by the formula CaCO₃. At its core, this compound consists of one calcium (Ca) ion bonded to one carbonate (CO₃) ion. The carbonate ion is a polyatomic ion with a trigonal planar geometry, comprising one carbon atom centrally bonded to three oxygen atoms in a symmetrical arrangement. This geometry allows for the formation of stable, solid structures, contributing to calcium carbonate’s common occurrence in nature as minerals such as calcite, aragonite, and vaterite. These forms differ in their crystallography: calcite forms a trigonal crystal system, aragonite in an orthorhombic system, and vaterite is hexagonal. This structural diversity allows calcium carbonate to manifest in various physical forms, from the hard shells of marine organisms to the stalactites and stalagmites found in caves, showcasing its vast presence and significance in the natural world.

Preparation of Calcium Carbonate

Calcium carbonate, a widely used compound, can be prepared using several straightforward methods. One common approach is the carbonation process, where calcium hydroxide reacts with carbon dioxide gas to form calcium carbonate and water. This reaction can be summarized by the equation:


This method not only occurs naturally, such as in limestone caves leading to stalactite and stalagmite formation, but is also utilized industrially to produce calcium carbonate for various uses.

Another method is the precipitation technique, which involves mixing solutions that contain calcium ions and carbonate ions. When these mix, calcium carbonate precipitates, or settles out of the solution as a solid, as shown by the equation:


This approach is particularly useful for producing calcium carbonate with specific particle sizes and shapes, catering to specialized applications.

Additionally, calcium carbonate can be directly obtained from natural sources like limestone, marble, and chalk, through processes that involve quarrying, crushing, and grinding these materials. Lastly, some organisms naturally produce calcium carbonate for their shells and skeletons, a process known as biogenic formation. Each of these methods provides a unique way to produce calcium carbonate, meeting the diverse demands across different industries.

Physical Properties of Calcium Carbonate

Property Description
Appearance White powder or colorless crystals
Molecular Weight 100.0869 g/mol
Density 2.71 g/cm³ (calcite), 2.93 g/cm³(aragonite)
Melting Point Decomposes at 825°C (1517°F) without melting
Solubility in Water Sparingly soluble (0.013 g/L at 25°C for calcite)
Crystal Structure Trigonal (calcite), Orthorhombic (aragonite)
Hardness (Mohs) 3 (calcite), 3.5-4 (aragonite)
Refractive Index 1.49 (calcite), 1.53 (aragonite)
pH Alkaline (basic)

Chemical Properties of Calcium Carbonate(CaCo₃)

Molecular Weight

Calcium carbonate has a molecular weight of 100.0869 g/mol, which is the sum of the atomic weights of one calcium atom, one carbon atom, and three oxygen atoms.


It is poorly soluble in pure water, with a solubility of approximately 0.013 g/L at 25°C. However, its solubility increases in the presence of carbon dioxide due to the formation of soluble calcium bicarbonate.


Being a base, calcium carbonate has an alkaline reaction. When dissolved in water, it can increase the pH of the solution due to the release of carbonate ions, which can combine with hydrogen ions.

Reaction with Acids

Calcium carbonate reacts with acids to produce carbon dioxide gas, water, and a salt. For example, when it reacts with hydrochloric acid, calcium chloride, water, and carbon dioxide are formed.
Equation: CaCO₃+2HCl→CaCl₂+H2O+CO₂CaCO₃​+2HCl→CaCl₂​+H₂O+CO₂​.

Formation of Complexes

It can form complexes with ions in water, contributing to the hardness of water. The calcium ions released from calcium carbonate can bind with other anions in water, such as sulfate or carbonate, forming compounds that precipitate out of solution.


Calcium carbonate is stable under normal conditions but can react with stronger acids, releasing carbon dioxide. It is also sensitive to acid rain, which can lead to the dissolution of calcium carbonate-based materials over time.

Thermal Decomposition

When heated above 840°C, calcium carbonate decomposes into calcium oxide (lime) and carbon dioxide gas, a reaction used in the lime-making process.

Equation: CaCO₃→CaO+CO₂CaCO₃→CaO+CO₂.

Calcium Carbonate (CaCo₃) Chemical Compound Information

Chemical Identifiers

Identification Value
CAS Registry Number 471-34-1
Beilstein Number 8008338
PubChem Compound ID 10112
SMILES Identifier C(=O)([O-])[O-].[Ca+2]
InChI Identifier InChI=1/CH2O3.Ca/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2/fCO3.Ca/q-2;m
EU Number 215-279-6
Gmelin Number 8544
RTECS Number FF9335000
MDL Number MFCD00010906

Uses of Calcium Carbonate

Uses Of Calcium carbonate (CaCO3)

Construction and Building Material

  • Cement and Concrete: Calcium carbonate is a key ingredient in the production of cement. It is also added to concrete mixtures as a filler to improve its strength and durability.
  • Manufacture of Glass: It serves as a source of lime in glass production, contributing to the glass’s chemical composition and physical properties.

Environmental Applications

  • Water Treatment: It is used to neutralize acidic conditions in both water and soil environments, improving the quality for drinking and agricultural use.
  • Flue Gas Desulfurization: Calcium carbonate reacts with sulfur dioxide present in flue gas, reducing air pollution from industrial plants.

Paper Industry

  • As a Filler and Coating Material: It provides brightness, opacity, and smoothness to paper, improving its quality for printing and writing.

Plastics and Rubber

  • Filler Material: It is incorporated into plastics to increase their strength and durability. It also adds to the opacity and whiteness of rubber products.


  • Soil Conditioner: Calcium carbonate is used to adjust soil pH levels, promoting healthier crop growth by improving nutrient availability and soil structure.

Health and Dietary Supplements

  • Calcium Supplement: It is a primary source of dietary calcium, essential for bone health and prevention of osteoporosis.
  • Antacid: It provides relief from acid indigestion and heartburn by neutralizing stomach acid.

Personal Care Products

  • Toothpaste and Dental Care: Calcium carbonate is used as an abrasive in toothpaste, helping to clean and whiten teeth.

Food Industry

  • Food Additive: It serves as a calcium source in food products and as an anti-caking agent to prevent clumping in powdered goods.

Paints and Coatings

  • Pigment and Filler: It is added to paints and coatings to improve color brightness and reduce costs.

Art and Restoration

  • Gesso: Artists use calcium carbonate mixed with glue as a preparation layer for canvas or sculpture.

Benefits Of Calcium Carbonate

Supports Bone and Teeth Health

  • Strengthens bones and teeth: Calcium carbonate is crucial for developing and maintaining strong bones and teeth, reducing the risk of osteoporosis and dental issues.

Aids in Medical Treatments

  • Acts as an antacid: It effectively neutralizes stomach acid, offering relief from heartburn and indigestion.
  • Treats calcium deficiencies: It’s used to manage conditions like osteoporosis, hypoparathyroidism, and certain muscle diseases.

Enhances Muscle and Heart Function

  • Regulates heart rhythm: Calcium is vital for a regular heartbeat and muscle contractions, supporting overall cardiovascular and muscular health.

Promotes Kidney Health

  • Prevents kidney stones: It can help prevent certain types of kidney stones by reducing the absorption of oxalate, a common stone-forming compound.

Industrial and Agricultural Applications

  • Versatile use: Beyond health, calcium carbonate is a key ingredient in products like paper, plastics, paint, and even as a soil conditioner and animal feed additive.

Side Effects of Calcium Carbonate

Common Side Effects

  • Digestive discomfort: Including gas, bloating, and constipation.
  • Nausea: Sometimes accompanied by vomiting, especially if taken without food.

Serious Side Effects

  • Hypercalcemia: High calcium levels in the blood, leading to various symptoms like frequent urination, thirst, and confusion.
  • Kidney stones: Increased risk with long-term use of high doses.
  • Medication interference: Can reduce the effectiveness of other medications.

Rare Side Effects

  • Allergic reactions: Including rash, itching, and severe dizziness.

Precautions and Recommendations

  • Dosage: It’s crucial to follow the recommended dosage and not exceed the daily recommended intake without consulting a healthcare provider.
  • Medical history: Individuals with a history of kidney stones, hyperparathyroidism, or chronic kidney disease should use calcium carbonate cautiously and under medical supervision.
  • Medication interactions: Consult with a healthcare provider about potential interactions between calcium carbonate and other medications you are taking.


Is Calcium Carbonate Good or Bad for You?

Calcium carbonate is beneficial for bone health and treating indigestion, but excessive intake can cause side effects like kidney stones.

Is Tums the Same as Calcium Carbonate?

Yes, Tums is a brand of antacid that primarily contains calcium carbonate, used to relieve heartburn and indigestion.

Is Calcium Carbonate the Same as Vitamin D?

No, calcium carbonate is a mineral used for calcium supplementation, whereas vitamin D helps the body absorb calcium but is not a mineral.

Why Should Calcium and Vitamin D Not Be Taken Together?

Taking large doses of calcium and vitamin D together can lead to excessive calcium in the blood, potentially causing harmful side effects.

Can You Take Vitamin D3 and Calcium Carbonate Together?

Yes, taking Vitamin D3 and calcium carbonate together is common and beneficial, as Vitamin D3 enhances calcium absorption from the gastrointestinal tract.

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