Calcium oxide

Last updated
Calcium oxide
Calcium-oxide-3D-vdW.png
Ionic crystal structure of calcium oxide
  Ca2+   O 2-
Calcium oxide powder.JPG
Powder sample of white calcium oxide
Names
IUPAC name
Calcium oxide
Other names
  • Lime
  • Quicklime
  • Burnt lime
  • Unslaked lime
  • Free lime (building)
  • Caustic lime
  • Pebble lime
  • Calcia
  • Oxide of calcium
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.013.763 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 215-138-9
E number E529 (acidity regulators, ...)
485425
KEGG
PubChem CID
RTECS number
  • EW3100000
UNII
UN number 1910
  • InChI=1S/Ca.O
    Key: ODINCKMPIJJUCX-UHFFFAOYSA-N
  • InChI=1/Ca.O/rCaO/c1-2
    Key: ODINCKMPIJJUCX-BFMVISLHAU
  • O=[Ca]
Properties
CaO
Molar mass 56.0774 g/mol
AppearanceWhite to pale yellow/brown powder
Odor Odorless
Density 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]
Reacts to form calcium hydroxide
Solubility in Methanol Insoluble (also in diethyl ether, octanol)
Acidity (pKa)12.8
−15.0×10−6 cm3/mol
Structure
Cubic, cF8
Thermochemistry
Std molar
entropy (S⦵298)
40 J·mol−1·K−1 [3]
−635 kJ·mol−1 [3]
Pharmacology
QP53AX18 ( WHO )
Hazards
GHS labelling:
GHS-pictogram-acid.svg GHS-pictogram-exclam.svg
Danger
H302, H314, H315, H335
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, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
3
0
2
W
Flash 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) ICSC 0409
Related compounds
Other anions
Other cations
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Calcium oxide (formula: Ca O), 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 compounds, in which carbonates, oxides, and hydroxides of calcium, silicon, magnesium, aluminium, and iron predominate. By contrast, quicklime specifically applies to the single compound calcium oxide. Calcium oxide that survives processing without reacting in building products, such as cement, is called free lime. [5]

Contents

Quicklime is relatively inexpensive. Both it and the chemical derivative calcium hydroxide (of which quicklime is the base anhydride) are important commodity chemicals.

Preparation

Calcium 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 behind. 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]

Hydroxyapatite's free CaO content rises with increased calcination temperatures and longer times. It also pinpoints particular temperature cutoffs and durations that impact the production of CaO, offering information on how calcination parameters impact the composition of the material.

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).
CaO (s) + H2O (l) ⇌ Ca(OH)2 (aq) (ΔHr = −63.7 kJ/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]

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. [23] 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. [24]

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. [25]

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. [26] Quicklime may have been used in medieval naval warfare – up to the use of "lime-mortars" to throw it at the enemy ships. [27]

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. [28]

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. [29] [ better source needed ]

Mineral

Calcium oxide is also a separate mineral species (with the unit formula CaO), named 'Lime'. [30] [31] It has an isometric crystal system, and can form a solid solution series with monteponite. The crystal is brittle, pyrometamorphic, and is unstable in moist air, quickly turning into portlandite (Ca(OH)2). [32]

Related Research Articles

<span class="mw-page-title-main">Cement</span> Hydraulic binder used in the composition of mortar and concrete

A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Concrete is the most widely used material in existence and is behind only water as the planet's most-consumed resource.

<span class="mw-page-title-main">Calcium carbonate</span> Chemical compound

Calcium carbonate is a chemical compound with the chemical formula CaCO3. It is a common substance found in rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skeletons and pearls. Materials containing much calcium carbonate or resembling it are described as calcareous. Calcium carbonate is the active ingredient in agricultural lime and is produced when calcium ions in hard water react with carbonate ions to form limescale. It has medical use as a calcium supplement or as an antacid, but excessive consumption can be hazardous and cause hypercalcemia and digestive issues.

<span class="mw-page-title-main">Sodium carbonate</span> Chemical compound

Sodium carbonate is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water. Historically, it was extracted from the ashes of plants grown in sodium-rich soils, and because the ashes of these sodium-rich plants were noticeably different from ashes of wood, sodium carbonate became known as "soda ash". It is produced in large quantities from sodium chloride and limestone by the Solvay process, as well as by carbonating sodium hydroxide which is made using the chloralkali process.

<span class="mw-page-title-main">Calcium hydroxide</span> Inorganic compound of formula Ca(OH)2

Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca(OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed with water. Annually, approximately 125 million tons of calcium hydroxide are produced worldwide.

<span class="mw-page-title-main">Calcium sulfate</span> Chemical derived from gypsum used in food and industry

Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO4 and related hydrates. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate is better known as plaster of Paris, and another occurs naturally as the mineral gypsum. It has many uses in industry. All forms are white solids that are poorly soluble in water. Calcium sulfate causes permanent hardness in water.

The Solvay process or ammonia–soda process is the major industrial process for the production of sodium carbonate (soda ash, Na2CO3). The ammonia–soda process was developed into its modern form by the Belgian chemist Ernest Solvay during the 1860s. The ingredients for this are readily available and inexpensive: salt brine (from inland sources or from the sea) and limestone (from quarries). The worldwide production of soda ash in 2005 was estimated at 42 million tonnes, which is more than six kilograms (13 lb) per year for each person on Earth. Solvay-based chemical plants now produce roughly three-quarters of this supply, with the remaining being mined from natural deposits. This method superseded the Leblanc process.

Calcination is thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting under restricted supply of ambient oxygen (i.e. gaseous O2 fraction of air), generally for the purpose of removing impurities or volatile substances and/or to incur thermal decomposition.

Pyrometallurgy is a branch of extractive metallurgy. It consists of the thermal treatment of minerals and metallurgical ores and concentrates to bring about physical and chemical transformations in the materials to enable recovery of valuable metals. Pyrometallurgical treatment may produce products able to be sold such as pure metals, or intermediate compounds or alloys, suitable as feed for further processing. Examples of elements extracted by pyrometallurgical processes include the oxides of less reactive elements like iron, copper, zinc, chromium, tin, and manganese.

<span class="mw-page-title-main">Lime (material)</span> Calcium oxides and/or hydroxides

Lime is an inorganic material composed primarily of calcium oxides and hydroxides. It is also the name for calcium oxide which occurs as a product of coal-seam fires and in altered limestone xenoliths in volcanic ejecta. The International Mineralogical Association recognizes lime as a mineral with the chemical formula of CaO. The word lime originates with its earliest use as building mortar and has the sense of sticking or adhering.

<span class="mw-page-title-main">Hydraulic lime</span> Substance used to make lime mortar

Hydraulic lime (HL) is a general term for a variety of lime different from calcium oxide (quicklime), that sets by hydration and consists of calcium silicate and calcium aluminate, compounds that can harden in contact with water. This contrasts with calcium hydroxide, also called slaked lime or air lime that is used to make lime mortar, the other common type of lime mortar, which sets by carbonation (re-absorbing carbon dioxide (CO2) from the air). Hydraulic lime provides a faster initial set and higher compressive strength than air lime, and hydraulic lime will set in more extreme conditions, including under water.

In inorganic chemistry, mineral hydration is a reaction which adds water to the crystal structure of a mineral, usually creating a new mineral, commonly called a hydrate.

<span class="mw-page-title-main">Cement clinker</span> Main component of Portland cement

Cement clinker is a solid material produced in the manufacture of portland cement as an intermediary product. Clinker occurs as lumps or nodules, usually 3 millimetres (0.12 in) to 25 millimetres (0.98 in) in diameter. It is produced by sintering limestone and aluminosilicate materials such as clay during the cement kiln stage.

<span class="mw-page-title-main">Calcium aluminate cements</span> Rapidly setting hydraulic cements

Calcium aluminate cements are cements consisting predominantly of hydraulic calcium aluminates. Alternative names are "aluminous cement", "high-alumina cement", and "Ciment fondu" in French. They are used in a number of small-scale, specialized applications.

<span class="mw-page-title-main">Alkali–silica reaction</span> Chemical reaction damaging concrete

The alkali–silica reaction (ASR), also commonly known as concrete cancer, is a deleterious internal swelling reaction that occurs over time in concrete between the highly alkaline cement paste and the reactive amorphous silica found in many common aggregates, given sufficient moisture.

<span class="mw-page-title-main">Carbon dioxide scrubber</span> Device which absorbs carbon dioxide from circulated gas

A carbon dioxide scrubber is a piece of equipment that absorbs carbon dioxide (CO2). It is used to treat exhaust gases from industrial plants or from exhaled air in life support systems such as rebreathers or in spacecraft, submersible craft or airtight chambers. Carbon dioxide scrubbers are also used in controlled atmosphere (CA) storage and carbon capture and storage processes.

<span class="mw-page-title-main">Concrete degradation</span> Damage to concrete affecting its mechanical strength and its durability

Concrete degradation may have many different causes. Concrete is mostly damaged by the corrosion of reinforcement bars due to the carbonatation of hardened cement paste or chloride attack under wet conditions. Chemical damage is caused by the formation of expansive products produced by chemical reactions, by aggressive chemical species present in groundwater and seawater, or by microorganisms Other damaging processes can also involve calcium leaching by water infiltration, physical phenomena initiating cracks formation and propagation, fire or radiant heat, aggregate expansion, sea water effects, leaching, and erosion by fast-flowing water.

The pozzolanic activity is a measure for the degree of reaction over time or the reaction rate between a pozzolan and Ca2+ or calcium hydroxide (Ca(OH)2) in the presence of water. The rate of the pozzolanic reaction is dependent on the intrinsic characteristics of the pozzolan such as the specific surface area, the chemical composition and the active phase content.

<span class="mw-page-title-main">Base anhydride</span>

A base anhydride is an oxide of a chemical element from group 1 or 2. They are obtained by removing water from the corresponding hydroxide base. If water is added to a base anhydride, a corresponding hydroxide salt can be [re]-formed.

Calcium looping (CaL), or the regenerative calcium cycle (RCC), is a second-generation carbon capture technology. It is the most developed form of carbonate looping, where a metal (M) is reversibly reacted between its carbonate form (MCO3) and its oxide form (MO) to separate carbon dioxide from other gases coming from either power generation or an industrial plant. In the calcium looping process, the two species are calcium carbonate (CaCO3) and calcium oxide (CaO). The captured carbon dioxide can then be transported to a storage site, used in enhanced oil recovery or used as a chemical feedstock. Calcium oxide is often referred to as the sorbent.

References

  1. 1 2 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.
  2. ↑ Calciumoxid (Archived 2013-12-30 at the Wayback Machine ). GESTIS database
  3. 1 2 Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A21. ISBN   978-0-618-94690-7.
  4. 1 2 3 4 NIOSH Pocket Guide to Chemical Hazards. "#0093". National Institute for Occupational Safety and Health (NIOSH).
  5. ↑ "free lime". DictionaryOfConstruction.com. Archived from the original on 2017-12-09.
  6. ↑ Merck Index of Chemicals and Drugs, 9th edition monograph 1650
  7. ↑ 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, Handbook of Environmental Engineering, vol. 5, Totowa, NJ: Humana Press, pp. 611–633, doi:10.1007/978-1-59745-173-4_14, ISBN   978-1-58829-860-7 , retrieved 2022-07-26
  8. ↑ "Lime throughout history | Lhoist - Minerals and lime producer". Lhoist.com. Retrieved 10 March 2022.
  9. ↑ Miller, M. Michael (2007). "Lime". Minerals Yearbook (PDF). U.S. Geological Survey. p. 43.13.
  10. 1 2 3 4 5 6 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
  11. ↑ Collie, Robert L. "Solar heating system" U.S. patent 3,955,554 issued May 11, 1976
  12. ↑ Gretton, Lel. "Lime power for cooking - medieval pots to 21st century cans". Old & Interesting. Retrieved 13 February 2018.
  13. ↑ "Compound Summary for CID 14778 - Calcium Oxide". PubChem.
  14. ↑ Gray, Theodore (September 2007). "Limelight in the Limelight". Popular Science: 84. Archived from the original on 2008-10-13. Retrieved 2009-03-31.
  15. ↑ Tel Aviv University (August 9, 2012). "Neolithic man: The first lumberjack?". phys.org. Retrieved 2023-02-02.
  16. ↑ 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.
  17. ↑ Connelly, Ashley Nicole (May 2012) Analysis and Interpretation of Neolithic Near Eastern Mortuary Rituals from a Community-Based Perspective Archived 2015-03-09 at the Wayback Machine . Baylor University Thesis, Texas
  18. ↑ Walker, Thomas A (1888). The Severn Tunnel Its Construction and Difficulties. London: Richard Bentley and Son. p.  92.
  19. ↑ "Scientific and Industrial Notes". Manchester Times . Manchester, England: 8. 13 May 1882.
  20. ↑ US Patent 255042, 14 March 1882
  21. ↑ 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.
  22. ↑ "Riddle solved: Why was Roman concrete so durable?", MIT News, January 6, 2023
  23. ↑ Plutarch, "Sertorius 17.1–7", Parallel Lives
  24. ↑ 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
  25. ↑ Croddy, Eric (2002). Chemical and biological warfare: a comprehensive survey for the concerned citizen. Springer. p. 128. ISBN   0-387-95076-1.
  26. ↑ David Hume (1756). History of England. Vol. I.
  27. ↑ Sayers, W. (2006). "The Use of Quicklime in Medieval Naval Warfare". The Mariner's Mirror. Volume 92. Issue 3. pp. 262–269.
  28. ↑ "Lime" (PDF). Prd-wret.s3-us-west-2.amazonaws.com. p. 96. Archived from the original (PDF) on 2021-12-19. Retrieved 2022-03-10.
  29. ↑ Mallinckrodt Baker Inc. - Strategic Services Division (December 8, 1996). "Hazards". ww25.hazard.com. Archived from the original on May 1, 2012. Retrieved 2023-02-02.{{cite web}}: CS1 maint: unfit URL (link)
  30. ↑ "List of Minerals". Ima-mineralogy.org. 21 March 2011.
  31. ↑ Fiquet, G.; Richet, P.; Montagnac, G. (Dec 1999). "High-temperature thermal expansion of lime, periclase, corundum and spinel". Physics and Chemistry of Minerals. 27 (2): 103–111. Bibcode:1999PCM....27..103F. doi:10.1007/s002690050246. S2CID   93706828 . Retrieved 9 February 2023.
  32. ↑ Tian, Lin, Yan, X. K., S. C., J., & Zhao, C. Y. (2022). "Lime". Mindat.org. doi:10.1016/j.cej.2021.131229 . Retrieved 10 March 2022.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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