Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term "lime" connotes calcium-containing inorganic materials, in which carbonates, oxides and hydroxides of calcium, silicon, magnesium, aluminium, and iron predominate. By contrast, quicklime specifically applies to the single chemical compound calcium oxide. Calcium oxide that survives processing without reacting in building products such as cement is called free lime.[5]
Quicklime is relatively inexpensive. Both it and a chemical derivative (calcium hydroxide, of which quicklime is the base anhydride) are important commodity chemicals.
The quicklime is not stable and, when cooled, will spontaneously react with CO2 from the air until, after enough time, it will be completely converted back to calcium carbonate unless slaked with water to set as lime plaster or lime mortar.
Annual worldwide production of quicklime is around 283 million tonnes. China is by far the world's largest producer, with a total of around 170 million tonnes per year. The United States is the next largest, with around 20 million tonnes per year.[9]
Approximately 1.8t of limestone is required per 1.0t of quicklime. Quicklime has a high affinity for water and is a more efficient desiccant than silica gel. The reaction of quicklime with water is associated with an increase in volume by a factor of at least 2.5.[10]
Uses
A demonstration of slaking of quicklime as a strongly exothermic reaction. Drops of water are added to pieces of quicklime. After a while, a pronounced exothermic reaction occurs ('slaking of lime'). The temperature can reach up to some 300 °C (572 °F).
The major use of quicklime is in the basic oxygen steelmaking (BOS) process. Its usage varies from about 30 to 50 kilograms (65–110 lb) per ton of steel. The quicklime neutralizes the acidic oxides, SiO2, Al2O3, and Fe2O3, to produce a basic molten slag.[10]
Ground quicklime is used in the production of aerated concrete blocks, with densities of ca. 0.6–1.0 g/cm3 (9.8–16.4 g/cu in).[10]
Quicklime and hydrated lime can considerably increase the load carrying capacity of clay-containing soils. They do this by reacting with finely divided silica and alumina to produce calcium silicates and aluminates, which possess cementing properties.[10]
Small quantities of quicklime are used in other processes; e.g., the production of glass, calcium aluminate cement, and organic chemicals.[10]
CaO (s) + H2O (l) ⇌ Ca(OH)2 (aq) (ΔHr = −63.7kJ/mol of CaO)
As it hydrates, an exothermic reaction results and the solid puffs up. The hydrate can be reconverted to quicklime by removing the water by heating it to redness to reverse the hydration reaction. One litre of water combines with approximately 3.1 kilograms (6.8 lb) of quicklime to give calcium hydroxide plus 3.54 MJ 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, cooking, and heating water without open flames. Several companies sell cooking kits using this heating method.[12]
It is known as a food additive to the FAO as an acidity regulator, a flour treatment agent and as a leavener.[13] It has E numberE529.
Light: When quicklime is heated to 2,400 °C (4,350 °F), it emits an intense glow. This form of illumination is known as a limelight, and was used broadly in theatrical productions before the invention of electric lighting.[14]
Cement: Calcium oxide is a key ingredient for the process of making cement.
As a cheap and widely available alkali. About 50% of the total quicklime production is converted to calcium hydroxide before use. Both quick- and hydrated lime are used in the treatment of drinking water.[10]
Petroleum industry: Water detection pastes contain a mix of calcium oxide and phenolphthalein. Should this paste come into contact with water in a fuel storage tank, the CaO reacts with the water to form calcium hydroxide. Calcium hydroxide has a high enough pH to turn the phenolphthalein a vivid purplish-pink color, thus indicating the presence of water.
Paper: Calcium oxide is used to regenerate sodium hydroxide from sodium carbonate in the chemical recovery at Kraft pulp mills.
Chemical or power production: Solid sprays or slurries of calcium oxide can be used to remove sulfur dioxide from exhaust streams in a process called flue-gas desulfurization.
Mining: Compressed lime cartridges exploit the exothermic properties of quicklime to break rock. A shot hole is drilled into the rock in the usual way and a sealed cartridge of quicklime is placed within and tamped. A quantity of water is then injected into the cartridge and the resulting release of steam, together with the greater volume of the residual hydrated solid, breaks the rock apart. The method does not work if the rock is particularly hard.[18][19][20]
Disposal of corpses: Historically, it was mistakenly believed that quicklime was efficacious in accelerating the decomposition of corpses. The application of quicklime can, in fact, promote preservation. Quicklime can aid in eradicating the stench of decomposition, which may have led people to the erroneous conclusion.[21]
Weapon
In 80 BC, the Roman general Sertorius deployed choking clouds of caustic lime powder to defeat the Characitani of Hispania, who had taken refuge in inaccessible caves.[22] A similar dust was used in China to quell an armed peasant revolt in 178 AD, when lime chariots equipped with bellows blew limestone powder into the crowds.[23]
Quicklime is also thought to have been a component of Greek fire. Upon contact with water, quicklime would increase its temperature above 150 °C (302 °F) and ignite the fuel.[24]
David Hume, in his History of England, recounts that early in the reign of Henry III, the English Navy destroyed an invading French fleet by blinding the enemy fleet with quicklime.[25] Quicklime may have been used in medieval naval warfare – up to the use of "lime-mortars" to throw it at the enemy ships.[26]
Substitutes
Limestone is a substitute for lime in many applications, which include agriculture, fluxing, and sulfur removal. Limestone, which contains less reactive material, is slower to react and may have other disadvantages compared with lime, depending on the application; however, limestone is considerably less expensive than lime. Calcined gypsum is an alternative material in industrial plasters and mortars. Cement, cement kiln dust, fly ash, and lime kiln dust are potential substitutes for some construction uses of lime. Magnesium hydroxide is a substitute for lime in pH control, and magnesium oxide is a substitute for dolomitic lime as a flux in steelmaking.[27]
Safety
Because of vigorous reaction of quicklime with water, quicklime causes severe irritation when inhaled or placed in contact with moist skin or eyes. Inhalation may cause coughing, sneezing, and labored breathing. It may then evolve into burns with perforation of the nasal septum, abdominal pain, nausea and vomiting. Although quicklime is not considered a fire hazard, its reaction with water can release enough heat to ignite combustible materials.[28]
Natural occurrence
It is noteworthy that CaO is also a separate mineral species, named lime. A pyrometamorphic mineral, it is rare, as it is unstable in moist air quickly turning into portlandite, Ca(OH)2.[29][30]
^Collie, Robert L. "Solar heating system" U.S. Patent 3,955,554 issued May 11, 1976
^Gretton, Lel. "Lime power for cooking - medieval pots to 21st century cans". Old & Interesting. Retrieved 13 February 2018.
^"Compound Summary for CID 14778 - Calcium Oxide". PubChem.
^Gray, Theodore (September 2007). . Popular Science: 84. Archived from the original on 2008-10-13. Retrieved 2009-03-31.
^Neolithic man: The first lumberjack?. Phys.org (August 9, 2012). Retrieved on 2013-01-22.
^Karkanas, P.; Stratouli, G. (2011). "Neolithic Lime Plastered Floors in Drakaina Cave, Kephalonia Island, Western Greece: Evidence of the Significance of the Site". The Annual of the British School at Athens. 103: 27–41. doi:10.1017/S006824540000006X. S2CID 129562287.
^Connelly, Ashley Nicole (May 2012) Analysis and Interpretation of Neolithic Near Eastern Mortuary Rituals from a Community-Based Perspective. Baylor University Thesis, Texas
^Walker, Thomas A (1888). The Severn Tunnel Its Construction and Difficulties. London: Richard Bentley and Son. p. 92.
^"Scientific and Industrial Notes". Manchester Times. Manchester, England: 8. 13 May 1882.
^Schotsmans, Eline M.J.; Denton, John; Dekeirsschieter, Jessica; Ivaneanu, Tatiana; Leentjes, Sarah; Janaway, Rob C.; Wilson, Andrew S. (April 2012). "Effects of hydrated lime and quicklime on the decay of buried human remains using pig cadavers as human body analogues". Forensic Science International. 217 (1–3): 50–59. doi:10.1016/j.forsciint.2011.09.025. hdl:2268/107339. PMID 22030481.
^Adrienne Mayor (2005), "Ancient Warfare and Toxicology", in Philip Wexler (ed.), Encyclopedia of Toxicology, vol. 4 (2nd ed.), Elsevier, pp. 117–121, ISBN0-12-745354-7
^Croddy, Eric (2002). Chemical and biological warfare: a comprehensive survey for the concerned citizen. Springer. p. 128. ISBN0-387-95076-1.
American Scientist (discussion of 14C dating of mortar)
CDC – NIOSH Pocket Guide to Chemical Hazards
January 07, 2023
calcium, oxide, commonly, known, quicklime, burnt, lime, widely, used, chemical, compound, white, caustic, alkaline, crystalline, solid, room, temperature, broadly, used, term, lime, connotes, calcium, containing, inorganic, materials, which, carbonates, oxide. Calcium oxide CaO commonly known as quicklime or burnt lime is a widely used chemical compound It is a white caustic alkaline crystalline solid at room temperature The broadly used term lime connotes calcium containing inorganic materials in which carbonates oxides and hydroxides of calcium silicon magnesium aluminium and iron predominate By contrast quicklime specifically applies to the single chemical compound calcium oxide Calcium oxide that survives processing without reacting in building products such as cement is called free lime 5 Calcium oxide NamesIUPAC name Calcium oxideOther names Quicklime burnt lime unslaked lime pebble lime calciaIdentifiersCAS Number 1305 78 83D model JSmol Interactive imageChEBI CHEBI 31344ChEMBL ChEMBL2104397ChemSpider 14095ECHA InfoCard 100 013 763EC Number 215 138 9E number E529 acidity regulators Gmelin Reference 485425KEGG C13140PubChem CID 14778RTECS number EW3100000UNII C7X2M0VVNHUN number 1910CompTox Dashboard EPA DTXSID5029631InChI InChI 1S Ca OKey ODINCKMPIJJUCX UHFFFAOYSA NInChI 1 Ca O rCaO c1 2Key ODINCKMPIJJUCX BFMVISLHAUSMILES O Ca PropertiesChemical formula CaOMolar mass 56 0774 g molAppearance White to pale yellow brown powderOdor OdorlessDensity 3 34 g cm3 1 Melting point 2 613 C 4 735 F 2 886 K 1 Boiling point 2 850 C 5 160 F 3 120 K 100 hPa 2 Solubility in water Reacts to form calcium hydroxideSolubility in Methanol Insoluble also in diethyl ether octanol Acidity pKa 12 8Magnetic susceptibility x 15 0 10 6 cm3 molStructureCrystal structure Cubic cF8ThermochemistryStd molarentropy S 298 40 J mol 1 K 1 3 Std enthalpy offormation DfH 298 635 kJ mol 1 3 PharmacologyATCvet code QP53AX18 WHO HazardsGHS labelling PictogramsSignal word DangerHazard statements H302 H314 H315 H335Precautionary statements P260 P261 P264 P270 P271 P280 P301 P312 P301 P330 P331 P302 P352 P303 P361 P353 P304 P340 P305 P351 P338 P310 P312 P321 P330 P332 P313 P362 P363 P403 P233 P405 P501NFPA 704 fire diamond 302WFlash point Non flammable 4 NIOSH US health exposure limits PEL Permissible TWA 5 mg m3 4 REL Recommended TWA 2 mg m3 4 IDLH Immediate danger 25 mg m3 4 Safety data sheet SDS Hazard comRelated compoundsOther anions Calcium sulfideCalcium hydroxideCalcium selenideCalcium tellurideOther cations Beryllium oxideMagnesium oxideStrontium oxideBarium oxideRadium oxideExcept where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Infobox references Quicklime is relatively inexpensive Both it and a chemical derivative calcium hydroxide of which quicklime is the base anhydride are important commodity chemicals Contents 1 Preparation 2 Uses 2 1 Weapon 2 2 Substitutes 3 Safety 4 Natural occurrence 5 References 6 External linksPreparation EditCalcium oxide is usually made by the thermal decomposition of materials such as limestone or seashells that contain calcium carbonate CaCO3 mineral calcite in a lime kiln This is accomplished by heating the material to above 825 C 1 517 F 6 7 a process called calcination or lime burning to liberate a molecule of carbon dioxide CO2 leaving quicklime This is also one of the few chemical reactions known in prehistoric times 8 CaCO3 s CaO s CO2 g The quicklime is not stable and when cooled will spontaneously react with CO2 from the air until after enough time it will be completely converted back to calcium carbonate unless slaked with water to set as lime plaster or lime mortar Annual worldwide production of quicklime is around 283 million tonnes China is by far the world s largest producer with a total of around 170 million tonnes per year The United States is the next largest with around 20 million tonnes per year 9 Approximately 1 8 t of limestone is required per 1 0 t of quicklime Quicklime has a high affinity for water and is a more efficient desiccant than silica gel The reaction of quicklime with water is associated with an increase in volume by a factor of at least 2 5 10 Uses Edit source source source source source source source source source source source source source source A demonstration of slaking of quicklime as a strongly exothermic reaction Drops of water are added to pieces of quicklime After a while a pronounced exothermic reaction occurs slaking of lime The temperature can reach up to some 300 C 572 F The major use of quicklime is in the basic oxygen steelmaking BOS process Its usage varies from about 30 to 50 kilograms 65 110 lb per ton of steel The quicklime neutralizes the acidic oxides SiO2 Al2O3 and Fe2O3 to produce a basic molten slag 10 Ground quicklime is used in the production of aerated concrete blocks with densities of ca 0 6 1 0 g cm3 9 8 16 4 g cu in 10 Quicklime and hydrated lime can considerably increase the load carrying capacity of clay containing soils They do this by reacting with finely divided silica and alumina to produce calcium silicates and aluminates which possess cementing properties 10 Small quantities of quicklime are used in other processes e g the production of glass calcium aluminate cement and organic chemicals 10 Heat Quicklime releases thermal energy by the formation of the hydrate calcium hydroxide by the following equation 11 CaO s H2O l Ca OH 2 aq DHr 63 7 kJ mol of CaO dd As it hydrates an exothermic reaction results and the solid puffs up The hydrate can be reconverted to quicklime by removing the water by heating it to redness to reverse the hydration reaction One litre of water combines with approximately 3 1 kilograms 6 8 lb of quicklime to give calcium hydroxide plus 3 54 MJ 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 cooking and heating water without open flames Several companies sell cooking kits using this heating method 12 It is known as a food additive to the FAO as an acidity regulator a flour treatment agent and as a leavener 13 It has E number E529 Light When quicklime is heated to 2 400 C 4 350 F it emits an intense glow This form of illumination is known as a limelight and was used broadly in theatrical productions before the invention of electric lighting 14 Cement Calcium oxide is a key ingredient for the process of making cement As a cheap and widely available alkali About 50 of the total quicklime production is converted to calcium hydroxide before use Both quick and hydrated lime are used in the treatment of drinking water 10 Petroleum industry Water detection pastes contain a mix of calcium oxide and phenolphthalein Should this paste come into contact with water in a fuel storage tank the CaO reacts with the water to form calcium hydroxide Calcium hydroxide has a high enough pH to turn the phenolphthalein a vivid purplish pink color thus indicating the presence of water Paper Calcium oxide is used to regenerate sodium hydroxide from sodium carbonate in the chemical recovery at Kraft pulp mills Plaster There is archeological evidence that Pre Pottery Neolithic B humans used limestone based plaster for flooring and other uses 15 16 17 Such Lime ash floor remained in use until the late nineteenth century Chemical or power production Solid sprays or slurries of calcium oxide can be used to remove sulfur dioxide from exhaust streams in a process called flue gas desulfurization Mining Compressed lime cartridges exploit the exothermic properties of quicklime to break rock A shot hole is drilled into the rock in the usual way and a sealed cartridge of quicklime is placed within and tamped A quantity of water is then injected into the cartridge and the resulting release of steam together with the greater volume of the residual hydrated solid breaks the rock apart The method does not work if the rock is particularly hard 18 19 20 Disposal of corpses Historically it was mistakenly believed that quicklime was efficacious in accelerating the decomposition of corpses The application of quicklime can in fact promote preservation Quicklime can aid in eradicating the stench of decomposition which may have led people to the erroneous conclusion 21 Weapon Edit In 80 BC the Roman general Sertorius deployed choking clouds of caustic lime powder to defeat the Characitani of Hispania who had taken refuge in inaccessible caves 22 A similar dust was used in China to quell an armed peasant revolt in 178 AD when lime chariots equipped with bellows blew limestone powder into the crowds 23 Quicklime is also thought to have been a component of Greek fire Upon contact with water quicklime would increase its temperature above 150 C 302 F and ignite the fuel 24 David Hume in his History of England recounts that early in the reign of Henry III the English Navy destroyed an invading French fleet by blinding the enemy fleet with quicklime 25 Quicklime may have been used in medieval naval warfare up to the use of lime mortars to throw it at the enemy ships 26 Substitutes Edit Limestone is a substitute for lime in many applications which include agriculture fluxing and sulfur removal Limestone which contains less reactive material is slower to react and may have other disadvantages compared with lime depending on the application however limestone is considerably less expensive than lime Calcined gypsum is an alternative material in industrial plasters and mortars Cement cement kiln dust fly ash and lime kiln dust are potential substitutes for some construction uses of lime Magnesium hydroxide is a substitute for lime in pH control and magnesium oxide is a substitute for dolomitic lime as a flux in steelmaking 27 Safety EditBecause of vigorous reaction of quicklime with water quicklime causes severe irritation when inhaled or placed in contact with moist skin or eyes Inhalation may cause coughing sneezing and labored breathing It may then evolve into burns with perforation of the nasal septum abdominal pain nausea and vomiting Although quicklime is not considered a fire hazard its reaction with water can release enough heat to ignite combustible materials 28 Natural occurrence EditIt is noteworthy that CaO is also a separate mineral species named lime A pyrometamorphic mineral it is rare as it is unstable in moist air quickly turning into portlandite Ca OH 2 29 30 References Edit a b Haynes William M ed 2011 CRC Handbook of Chemistry and Physics 92nd ed Boca Raton FL CRC Press p 4 55 ISBN 1 4398 5511 0 Calciumoxid Archived 2013 12 30 at the Wayback Machine GESTIS database a b Zumdahl Steven S 2009 Chemical Principles 6th Ed Houghton Mifflin Company p A21 ISBN 978 0 618 94690 7 a b c d NIOSH Pocket Guide to Chemical Hazards 0093 National Institute for Occupational Safety and Health NIOSH free lime Archived 2017 12 09 at the Wayback Machine DictionaryOfConstruction com Merck Index of Chemicals and Drugs 9th edition monograph 1650 Kumar Gupta Sudhir Ramakrishnan Anushuya Hung Yung Tse 2007 Wang Lawrence K Hung Yung Tse Shammas Nazih K eds Lime Calcination Advanced Physicochemical Treatment Technologies Totowa NJ Humana Press vol 5 pp 611 633 doi 10 1007 978 1 59745 173 4 14 ISBN 978 1 58829 860 7 retrieved 2022 07 26 Lime throughout history Lhoist Minerals and lime producer Lhoist com Retrieved 10 March 2022 Miller M Michael 2007 Lime Minerals Yearbook PDF U S Geological Survey p 43 13 a b c d e f Tony Oates 2007 Lime and Limestone Ullmann s Encyclopedia of Industrial Chemistry 7th ed Wiley pp 1 32 doi 10 1002 14356007 a15 317 ISBN 978 3527306732 Collie Robert L Solar heating system U S Patent 3 955 554 issued May 11 1976 Gretton Lel Lime power for cooking medieval pots to 21st century cans Old amp Interesting Retrieved 13 February 2018 Compound Summary for CID 14778 Calcium Oxide PubChem Gray Theodore September 2007 Limelight in the Limelight Popular Science 84 Archived from the original on 2008 10 13 Retrieved 2009 03 31 Neolithic man The first lumberjack Phys org August 9 2012 Retrieved on 2013 01 22 Karkanas P Stratouli G 2011 Neolithic Lime Plastered Floors in Drakaina Cave Kephalonia Island Western Greece Evidence of the Significance of the Site The Annual of the British School at Athens 103 27 41 doi 10 1017 S006824540000006X S2CID 129562287 Connelly Ashley Nicole May 2012 Analysis and Interpretation of Neolithic Near Eastern Mortuary Rituals from a Community Based Perspective Baylor University Thesis Texas Walker Thomas A 1888 The Severn Tunnel Its Construction and Difficulties London Richard Bentley and Son p 92 Scientific and Industrial Notes Manchester Times Manchester England 8 13 May 1882 US Patent 255042 14 March 1882 Schotsmans Eline M J Denton John Dekeirsschieter Jessica Ivaneanu Tatiana Leentjes Sarah Janaway Rob C Wilson Andrew S April 2012 Effects of hydrated lime and quicklime on the decay of buried human remains using pig cadavers as human body analogues Forensic Science International 217 1 3 50 59 doi 10 1016 j forsciint 2011 09 025 hdl 2268 107339 PMID 22030481 Plutarch Sertorius 17 1 7 Parallel Lives Adrienne Mayor 2005 Ancient Warfare and Toxicology in Philip Wexler ed Encyclopedia of Toxicology vol 4 2nd ed Elsevier pp 117 121 ISBN 0 12 745354 7 Croddy Eric 2002 Chemical and biological warfare a comprehensive survey for the concerned citizen Springer p 128 ISBN 0 387 95076 1 David Hume 1756 History of England Vol I Sayers W 2006 The Use of Quicklime in Medieval Naval Warfare The Mariner s Mirror Volume 92 Issue 3 pp 262 269 Lime PDF Prd wret s3 us west 2 amazonaws com p 96 Retrieved 2022 03 10 CaO MSDS Archived 2012 05 01 at the Wayback Machine Hazard com Lime Mindat org Retrieved 10 March 2022 List of Minerals Ima mineralogy org 21 March 2011 External links Edit Wikimedia Commons has media related to Calcium oxide Lime Statistics amp Information from the United States Geological Survey Factors Affecting the Quality of Quicklime American Scientist discussion of 14C dating of mortar Chemical of the Week Lime Material Safety Data Sheet CDC NIOSH Pocket Guide to Chemical Hazards Retrieved from https en wikipedia org w index php title Calcium oxide amp oldid 1119691416, wikipedia, wiki, book, books, library,
