Calcium oxide
IUPAC name	Calcium Oxide
Properties
Molecular formula	CaO
Molar mass	56.077 g/mol
Appearance	White solid
Density	3350 kg/m³, solid
Melting point	2572 °C (2845 K) IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... A chemical formula is an easy way of expressing information about the atoms that constitute a particular chemical compound. ... The letters CAO are used to denote several things: Central Applications Office - Irish organisation that oversees tertiary education applications Chief Administrative Officer of a company Chief Accounting Officer of a company Collectieve Arbeids Overeenkomst (Collective Work Agreement), Dutch term for a collective employment contract framework Computer Aided Optimization Computer Assisted... Molar mass is the mass of one mole of a chemical element or chemical compound. ... For other uses, see Density (disambiguation). ... The melting point of a solid is the temperature range at which it changes state from solid to liquid. ... For other uses, see Celsius (disambiguation). ... For other uses, see Kelvin (disambiguation). ...
Boiling point	2850 °C (3123 K) Italic text This article is about the boiling point of liquids. ... For other uses, see Celsius (disambiguation). ... For other uses, see Kelvin (disambiguation). ...
Solubility in water	reacts
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Calcium oxide (CaO), commonly known as burnt lime, lime or quicklime, is a widely used chemical compound. It is a white, caustic and alkaline crystalline solid. As a commercial product, lime often also contains magnesium oxide, silicon oxide and smaller amounts of aluminium oxide and iron oxide. Solubility is a chemical property referring to the ability for a given substance, the solute, to dissolve in a solvent. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... The plimsoll symbol as used in shipping In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals exactly). ... This article or section does not adequately cite its references or sources. ... Look up chemical compound in Wiktionary, the free dictionary. ... A caustic substance, in chemistry, is one that causes corrosion, the deterioration of a material. ... Alkaline redirects here. ... For other uses, see Crystal (disambiguation). ... General Name, symbol, number magnesium, Mg, 12 Chemical series alkaline earth metals Group, period, block 2, 3, s Appearance silvery white solid at room temp Standard atomic weight 24. ... Not to be confused with Silicone. ... Aluminum redirects here. ... General Name, symbol, number iron, Fe, 26 Chemical series transition metals Group, period, block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ...

Calcium oxide is usually made by the thermal decomposition of materials such as limestone, that contain calcium carbonate (CaCO₃; mineral name: calcite) in a lime kiln. This is accomplished by heating the material to above 825°C,^[1] a process called calcination or lime-burning, to liberate a molecule of carbon dioxide (CO₂); leaving CaO. This process is reversible, since once the quicklime product has cooled, it immediately begins to absorb carbon dioxide from the air, until, after enough time, it is completely converted back to calcium carbonate. Calcination of limestone is one of the first chemical reactions discovered by man and was known in prehistory. For other uses, see Calcium (disambiguation). ... An oxide is a chemical compound containing at least one oxygen atom and other elements. ... For other uses, see Limestone (disambiguation). ... Calcium carbonate is a chemical compound, with the chemical formula CaCO3. ... Doubly refracting Calcite from Iceberg claim, Dixon, New Mexico. ... A 19th century limekiln A limekiln is a kiln used to produce quicklime by the calcination of limestone (calcium carbonate). ... For other uses, see Celsius (disambiguation). ... Calcination is the process of heating a substance to a high temperature, but below its melting or fusing point, to bring about thermal decomposition or a phase transition in its physical or chemical constitution. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Calcium carbonate is a chemical compound, with the chemical formula CaCO3. ... Stonehenge, England, erected by Neolithic peoples ca. ...

Up until the 20th century, quicklime was used as a disinfectant, usually in a 10% solution called milk of lime. However, it had the disadvantage of decomposing rapidly on exposure to air and moisture, and the burnt lime had to be fresh and unslaked.^[2] (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999 in the...

Usage

As hydrated or slaked lime, Ca(OH)₂ (mineral name: portlandite), it is used in mortar and plaster to increase the rate of hardening as well as to improve adhesion^{[citation needed]}. Hydrated lime is very simple to make as lime is a basic anhydride and reacts vigorously with water. Lime is also used in glass production and its ability to react with silicates is also used in modern metal production (steel, magnesium, aluminium and other metals) industries to remove impurities as slag. Calcium hydroxide is a chemical compound with the chemical formula Ca(OH)2. ... It has been suggested that this article or section be merged with Calcium hydroxide. ... Mortar holding weathered bricks. ... This article is about the building material. ... Hydrate is a term which means different things in inorganic chemistry and organic chemistry. ... Structure of anhydride. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... This article is about the material. ... For other uses, see Steel (disambiguation). ... General Name, symbol, number magnesium, Mg, 12 Chemical series alkaline earth metals Group, period, block 2, 3, s Appearance silvery white solid at room temp Standard atomic weight 24. ... Aluminum redirects here. ... Slag is also an early play by David Hare. ...

It is also used in water and sewage treatment to reduce acidity, to soften, as a flocculant, and to remove phosphates and other impurities; in paper making to dissolve lignin, as a coagulant, and in bleaching; in agriculture to improve acidic soils; and in pollution control, in gas scrubbers to desulfurize waste gases and to treat many liquid effluents. It has traditionally been used in the burial of bodies in open graves, to hide the smell of decomposition, as well as in forensic science, to reveal fingerprints. It is a refractory and a dehydrating agent and is used to purify citric acid, glucose, dyes and as a CO₂ absorber. It is also used in pottery, paints and the food industry. Furthermore, quicklime is used in epidemics, plagues, and disasters to disintegrate bodies in order to help fight the spread of disease. CaO is a key ingredient in the nixtamalization process used to create corn hominy and masa or tortilla dough. For other uses, see acid (disambiguation). ... This article needs additional references or sources for verification. ... A phosphate, in inorganic chemistry, is a salt of phosphoric acid. ... For other uses, see Paper (disambiguation). ... Lignin (sometimes lignen) is a chemical compound (complex, highly cross-linked aromatic polymer) that is most commonly derived from wood and is an integral part of the cell walls of plants, especially in tracheids, xylem fibres and sclereids. ... A flocculant is a chemical which causes the particles in a colloidal dispersal to clump together and form flocs. Flocculants are commonly used to facilitate the removal by filtration of particles of impurity from a liquid which would otherwise be too fine to be caught by a filter. ... This article is about the chemical whitener. ... Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland For other uses, see Soil (disambiguation). ... Air pollution Pollution is the introduction of pollutants (whether chemical substances, or energy such as noise, heat, or light) into the environment to such a point that its effects become harmful to human health, other living organisms, or the environment. ... This article is about the chemical element. ... The term refractory can refer to multiple things: A refractory clergyman is one who refused to swear an oath to the French Revolution-era French state under the Civil Constitution of the Clergy. ... Citric acid is a weak organic acid found in citrus fruits. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... Look up dye in Wiktionary, the free dictionary. ... Unfired green ware pottery on a traditional drying rack at Conner Prairie living history museum. ... For other uses, see Paint (disambiguation). ... Nixtamalization is the process whereby ripe maize grains are soaked and cooked in an alkaline solution, usually lime based, to cause the transparent outer hull, the pericarp, to separate from the grain. ... This article is about the maize plant. ... Hominy or nixtamal is dried, treated maize (corn) kernels. ... Masa, or masa nixtamalera, is a fine maize dough made from masa harina, ground hominy flour. ...

A relatively inexpensive substance, CaO produces heat energy by the formation of the hydrate, as in the following equation:^[3] For other uses, see Heat (disambiguation) In physics, heat, symbolized by Q, is energy transferred from one body or system to another due to a difference in temperature. ...

CaO + H₂O ↔ Ca(OH)₂ + 63.7kJ/mol of CaO

The hydrate can be reconverted to calcium oxide by removing the water in the reversible equation. If the hydrated lime is heated to redness, the CaO will be regenerated to reverse the reaction. As it hydrates, an exothermic reaction results. One litre of water combines with approximately 3.1kg of calcium oxide to give calcium hydroxide plus 3.54MJ of energy. This process can be used to provide a convenient portable source of heat, as for on-the-spot food warming in a self-heating can. The joule (IPA: or ) (symbol: J) is the SI unit of energy. ... A self-heating can is an extension of the common food can. ...

World lime annual production is around 130 million metric tons, with the USA and China the largest producers, each producing around 20 million metric tons.[1]

References

1. ^ Merck Index of chemicals and Drugs , 9th ed. monograph 1650
2. ^ A Complete Handbook for the Sanitary Troops of the U.S. Army and Navy (1917)
3. ^ US Patent 3,955,554, Solar heating system.

External links

• An authoritative discussion of lime and its uses (US context) by the US Geological Survey
• Factors Affecting the Quality of Quicklime
• American Scientist (discussion of C¹⁴ dating of mortar)
• Chemical of the Week -- Lime