[Chemistry Class Notes] on Calcium Carbonate Pdf for Exam

Calcium carbonate is a chemical inorganic compound having the chemical formula CaCO3.It is also one of the most popular chemicals which is encountered first in school classrooms, where the use of chalk (which is a form of CaCO3) is found. It is found in the crust of the earth.  It is available in various forms, such as limestone, marble, and more. Although they are available in different forms, they are chemically similar and differ only physically. They are also called calcite. The symbol of calcium carbonate can be given as CaCO3.

Types of Calcium Carbonate found in the Environment

Calcium carbonate is present in three polymorphic forms – calcite, aragonite and vaterite. 

Calcite: It is the most stable and the least soluble. A rock-forming mineral, it is commonly found in sedimentary, metamorphic, and igneous rocks. Calcite is a common constituent of sedimentary rocks like limestone and marble. It is used extensively in construction material, agricultural soil treatment, pharmaceuticals and many more areas. 

Argonite: It is less stable and more soluble than calcite. It is formed by biological and physical processes, including precipitation from marine and freshwater environments. Aragonite provides ingredients to sea life, and also maintains the pH levels to its natural level. It is used to remove pollutants like zinc, cobalt and lead from contaminated wastewaters.

Vaterite: Hexagonal in shape, vaterite, is less stable than calcite and aragonite, with a higher solubility. It is found naturally in springs, organic tissue, urinary calculi, gallstones, and plants. It finds its uses in regenerative medicine and a range of personal care products. 

 

CaCO3 Structure

Calcium carbonate is odorless, and a non-toxic compound found commonly as a white mineral that occurs naturally in limestones, chalks, and marbles.

The Calcium Carbonate structure can be given as follows:

Calcium Carbonate Formula

• Calcium Carbonate is a chemical compound having the chemical formula CaCO3.

• It is a white and insoluble powder-like substance that occurs naturally in minerals, marble, chalk, limestone, shells, calcite, pearl, and other related compounds.

• Medicinally, we use it as an antacid or a calcium supplement. It can also be used as cosmetics fillers. It is added to swimming pools as a disinfectant agent and also as a pH corrector.

• We can find it in extensive usage in the manufacturing industry as an ingredient for quick lime and cement and building material (marble).

Preparation of CaCO3

There is also another method to obtain the calcite by adding sodium carbonate to calcium chloride.

CaCl2 + Na2CO3 → CaCO3 + 2NaCl

Ca (OH)2 + CO2 → CaCO3 + H2O

When carbon dioxide is passed in excess amounts, it leads to the formation of calcium hydrogen-carbonate.

• It can be prepared on a large scale by passing carbon dioxide gas through calcium hydroxide (otherwise called slaked lime). However, if there is an excess passing of carbon dioxide, it results in the formation of soluble calcium hydrogen-carbonate.

Ca(OH)2 + CO2→ CaCO3 + H2O

Commercial Production of Calcium Carbonate

Calcium carbonate can be produced commercially in two different grades. Both these grades compete industrially primarily based on the particle size and the characteristics that are imparted to a product.

• Ground Calcium Carbonate – It is produced via extraction and processing naturally occurring deposits. The GCC crystal shape is irregularly rhombohedral, and its distribution is a broader size.

• Precipitated Calcium Carbonate – This is produced via chemical precipitation with a carbocation process or as a by-product of a few bulk chemical processes. The shape of the PCC crystal depends on the product, and the particles are more regular and uniform with a distribution of narrow size.

PCC has smaller particles that have higher purity, are less abrasive, and tend to have higher brightness than GCC.

Physical Properties of CaCO3

• Calcium Carbonate is a fluffy powder.

• It decomposes to form carbon dioxide when heated up to 1200K.

• It liberates carbon dioxide as a by-product when it reacts with dilute acid.

• While reacting with dilute acids, calcium carbonate produces carbon dioxide.

• The molecular weight of CaCO3 100.0869 g/mol.

• The molecular mass of calcium carbonate is 100.0869 g/mol.

 

Application of Calcium Carbonate

• Calcium carbonate is employed largely in the paper and pulp industries. It can also be used as a pigment and filter, making possible the production of a whiter and higher quality pigment compared to other minerals.

• Calcium carbonate is used in the construction industry as a filler in concrete, increasing its appearance and durability and purifying metals to use in construction applications.

• The other application of calcium carbonate is in fertilizers in providing calcium to plants and pH stabilization of the soil.

• It can also be an additive to food products for humans and livestock animals and as a vitamin supplement.

• Calcium carbonate is employed in water and sewer treatment plants in the removal of impurities and acidity.

Calcium Carbonate Uses

The uses of calcium carbonate are listed as follows:

• Calcium Carbonate plays an important role in the construction department, whether as an ingredient in cement or as a building material (marble).

• It can be used in medicinal industries in the manufacturing of calcium dietary supplements, pharmaceutical filler in tablets, and antacids, which are made of base materials.

• It can also be used in the manufacturing of paper, paints, plastics, and more.

• It is used as calcium supplements.

• It is used to make building materials like ceramic tiles

• Blackboard chalk. 

• Iron ore purification, 

• Oil well drilling fluids.

• Paints, adhesives, and sealants. 

• It is used in hemodialysis treatment. 

• It finds its use in food preservatives and toothpaste.

• It is used in refining sugar from sugar beet. 

• It is often added to swimming pools, as a pH corrector to maintain alkalinity.

• In agriculture, it is used to maintain the right acidity of soil and supply calcium that the growing plants require.

Other Important Information

If this medicine or compound has been prescribed for you, keep all the appointments with your doctor so that your response to this compound can be checked. And, do not let anyone else take your medicine.

It is also important for you to keep a written list of both prescription and nonprescription (over-the-counter) medicines you are taking and also any products, including minerals, vitamins, or other dietary supplements. Besides, you should carry this list with you every time you visit a doctor or if you get admitted to a hospital. It is also important to carry this with you in case of emergencies.

Interesting Facts

• It is said that Cleopatra used to dissolve pearls made of calcium carbonate in vinegar and drink the solution, as part of her extravagance.

• Stalagmites and stalactites are formed when calcium bicarbonate dissolved in the groundwater reaches the top of a cave and loses carbon dioxide (CO₂). When calcium bicarbonate gives up CO₂, it gets converted into calcium carbonate, which precipitates on the roof to form a stalactite. When the calcium bicarbonate does not lose the carbon dioxide before dripping down and falling on the floor, the calcium carbonate builds up to form a stalagmite on the floor instead.

• Calcium Carbonate is used to counter the increased acidity in lakes and other water bodies, and purify water and wastewater, and treat waste gases by removing sulfur and nitrogen oxides that pollute the air.