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{{Chembox
{{Chembox
| Verifiedfields = changed
|Verifiedfields = changed
| Watchedfields = changed
|Watchedfields = changed
| verifiedrevid = 486593291
|verifiedrevid = 486593291
| ImageFile = HgOpowder.jpg
|ImageFile = HgOpowder.jpg
| ImageName = Mercury(II) oxide
|ImageName = Mercury(II) oxide
| ImageFile1 = Montroydite-3D-ionic.png
|ImageFile1 = Montroydite-3D-ionic.png
| ImageName1 = Mercury(II) oxide
|ImageName1 = Mercury(II) oxide
| IUPACName = Mercury(II) oxide
|IUPACName = Mercury(II) oxide
| OtherNames = Mercuric oxide<br />[[Montroydite]]<br />[[Red mercury]]
|OtherNames = Mercuric oxide<br />[[Montroydite]]<br />[[Red mercury]]
|Section1={{Chembox Identifiers
|Section1={{Chembox Identifiers
| CASNo = 21908-53-2
|CASNo = 21908-53-2
| CASNo_Ref = {{cascite|correct|CAS}}
|CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
|UNII_Ref = {{fdacite|correct|FDA}}
| UNII = IY191986AO
|UNII = IY191986AO
| UNNumber = 1641
|UNNumber = 1641
| RTECS = OW8750000
|RTECS = OW8750000
| PubChem = 30856
|PubChem = 30856
| KEGG_Ref = {{keggcite|correct|kegg}}
|KEGG_Ref = {{keggcite|correct|kegg}}
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/Hg.O
|StdInChI = 1S/Hg.O
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = UKWHYYKOEPRTIC-UHFFFAOYSA-N
|StdInChIKey = UKWHYYKOEPRTIC-UHFFFAOYSA-N
| SMILES = [Hg]=O
|SMILES = [Hg]=O
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 28626
|ChemSpiderID = 28626
| KEGG = C18670
|KEGG = C18670
}}
}}
|Section2={{Chembox Properties
|Section2={{Chembox Properties
| Hg=1 | O=1
|Hg=1 | O=1
| Appearance = Yellow or red solid
|Appearance = Yellow or red solid
| Odor = odorless
|Odor = odorless
| Density = 11.14 g/cm<sup>3</sup>
|Density = 11.14 g/cm<sup>3</sup>
| Solubility = 0.0053 g/100 mL (25 °C) <br> 0.0395 g/100 mL (100 °C)
|Solubility = 0.0053 g/100 mL (25 °C) <br /> 0.0395 g/100 mL (100 °C)
| SolubleOther = insoluble in [[ethanol|alcohol]], [[diethyl ether|ether]], [[acetone]], [[ammonia]]
|SolubleOther = insoluble in [[ethanol|alcohol]], [[diethyl ether|ether]], [[acetone]], [[ammonia]]
| MeltingPtC = 500
|MeltingPtC = 500
| MeltingPt_notes = (decomposes)
|MeltingPt_notes = (decomposes)
| BandGap = 2.2 eV<ref name=landolt>{{cite book| chapter = Mercury oxide (HgO) crystal structure, physical properties| volume = 41B| doi = 10.1007/b71137| publisher = Springer-Verlag| year = 1999| pages = 1–7| isbn = 978-3-540-64964-9 | work = Landolt-Börnstein – Group III Condensed Matter|title=Semiconductors · II-VI and I-VII Compounds; Semimagnetic Compounds| series = Landolt-Börnstein - Group III Condensed Matter}}</ref>
|BandGap = 2.2 eV<ref name=landolt>{{cite book| chapter = Mercury oxide (HgO) crystal structure, physical properties| volume = 41B| doi = 10.1007/b71137| publisher = Springer-Verlag| year = 1999| pages = 1–7| isbn = 978-3-540-64964-9 |title=Semiconductors · II-VI and I-VII Compounds; Semimagnetic Compounds| series = Landolt-Börnstein - Group III Condensed Matter| editor1-last = Madelung| editor1-first = O| editor2-first = U| editor2-last = Rössler| editor3-first = M| editor3-last = Schulz}}</ref>
| RefractIndex = 2.5 (550 nm)<ref name=landolt/>
|RefractIndex = 2.5 (550 nm)<ref name=landolt/>
| MagSus = &minus;44.0·10<sup>−6</sup> cm<sup>3</sup>/mol
|MagSus = −44.0·10<sup>−6</sup> cm<sup>3</sup>/mol
}}
}}
|Section3={{Chembox Structure
|Section3={{Chembox Thermochemistry
⚫
|DeltaHf = −90&nbsp;kJ·mol<sup>−1</sup><ref name=b1>{{cite book| author = Zumdahl, Steven S.|title =Chemical Principles 6th Ed.| publisher = Houghton Mifflin Company| year = 2009| isbn = 978-0-618-94690-7|page=A22}}</ref>
| Coordination = orthorhombic
⚫
|Entropy = 70&nbsp;J·mol<sup>−1</sup>·K<sup>−1</sup><ref name=b1/>
| CrystalStruct =
⚫
}}
| Dipole =
⚫
|Section4={{Chembox Hazards
⚫
}}
|MainHazards = Extremely toxic, environmental pollutant
|Section4={{Chembox Thermochemistry
⚫
|ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics0981.htm ICSC 0981]
⚫
| DeltaHf = −90&nbsp;kJ·mol<sup>−1</sup><ref name=b1>{{cite book| author = Zumdahl, Steven S.|title =Chemical Principles 6th Ed.| publisher = Houghton Mifflin Company| year = 2009| isbn = 978-0-618-94690-7|page=A22}}</ref>
⚫
|GHSPictograms = {{GHS06}} {{GHS08}} {{GHS09}}
⚫
| Entropy = 70&nbsp;J·mol<sup>−1</sup>·K<sup>−1</sup><ref name=b1/>
|GHSSignalWord = Danger
⚫
}}
|HPhrases = {{H-phrases|H300+H310+H330|H372|H410}}
⚫
|Section7={{Chembox Hazards
|PPhrases = {{P-phrases|P260|P262|P264|P270|P271|P273|P280|P284|P301+P316|P302+P352|P304+P340|P316|P320|P321|P330|P361+P364|P391|P403+P233|P405|P501}}
| MainHazards = Highly toxic
|GHS_ref = <ref>{{cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/30856#datasheet=LCSS|title=Laboratory Chemical Safety Summary (LCSS): Mercuric oxide|id=CID 30856|website=[[PubChem]]|publisher=[[National Center for Biotechnology Information]]|access-date=2022-04-14}}</ref>
⚫
| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics0981.htm ICSC 0981]
⚫
|NFPA-H = 4
⚫
| GHSPictograms = {{GHS06}} {{GHS08}} {{GHS09}}
| NFPA-H = 4
|NFPA-F = 0
| NFPA-F = 0
|NFPA-R = 1
|NFPA_ref = <ref>{{cite web|url=https://www.fishersci.com/store/msds?partNumber=AC316791000&countryCode=US&language=en|format=PDF|title=Safety Data Sheet: Mercury(II) oxide|id=Cat No. AC316790000|publisher=[[Thermo Fisher Scientific]]|date=2021-12-25|access-date=2022-04-13}}</ref>
⚫
| NFPA-R = 2
⚫
|FlashPt = Non-flammable
| NFPA_ref =
|LD50 = 18 mg/kg (oral, rat)<ref>{{cite web|url=https://chem.nlm.nih.gov/chemidplus/rn/21908-53-2|title=Mercuric oxide [ISO]|id=CAS RN: 21908-53-2|website=ChemIDPlus Advanced|publisher=[[United States National Library of Medicine]]|access-date=2022-04-14}}</ref>
⚫
| FlashPt = Non-flammable
⚫
}}
| PEL =
⚫
|Section5={{Chembox Related
| LD50 = 18 mg/kg (oral, rat)<ref>{{cite web|url=http://chem.sis.nlm.nih.gov/chemidplus/rn/21908-53-2|title=ChemIDplus - 21908-53-2 - UKWHYYKOEPRTIC-UHFFFAOYSA-N - Mercuric oxide [ISO] - Similar structures search, synonyms, formulas, resource links, and other chemical information.|first=Michael|last=Chambers|date=|website=chem.sis.nlm.nih.gov}}</ref>
⚫
|OtherAnions = [[Mercury sulfide]]<br />[[Mercury selenide]]<br />[[Mercury telluride]]
⚫
}}
⚫
|OtherCations = [[Zinc oxide]]<br />[[Cadmium oxide]]
⚫
|Section8={{Chembox Related
⚫
|OtherCompounds = [[Mercury(I) oxide]]
⚫
| OtherAnions = [[Mercury sulfide]]<br/>[[Mercury selenide]]<br/>[[Mercury telluride]]
⚫
}}
⚫
| OtherCations = [[Zinc oxide]]<br/>[[Cadmium oxide]]
⚫
| OtherCompounds = [[Mercury(I) oxide]]
}}
}}
}}


'''Mercury(II) oxide''', also called '''mercuric oxide''' or simply '''mercury oxide''', has a formula of [[Mercury (element)|Hg]][[oxygen|O]]. It has a red or orange color. Mercury(II) oxide is a solid at room temperature and pressure. The mineral form [[montroydite]] is very rarely found.
'''Mercury(II) oxide''', also called '''mercuric oxide''' or simply '''mercury oxide''', is the [[inorganic compound]] with the formula [[Mercury (element)|Hg]][[oxygen|O]]. It has a red or orange color. Mercury(II) oxide is a solid at room temperature and pressure. The mineral form [[montroydite]] is very rarely found.


==History==
==History==
An experiment for the preparation of mercuric oxide was first described by 11th century Arab-Spanish alchemist, [[Maslama al-Majriti]], in ''Rutbat al-hakim.''<ref>{{Cite book|last=Holmyard |first=E. J. |url=https://books.google.com/books?id=uLsOAwAAQBAJ&dq=majriti+mercuric+oxide&pg=PA257 |title=Inorganic chemistry |date=1931 |publisher=Рипол Классик |isbn=978-5-87636-953-6 |language=en}}</ref> It was historically called [[wikt:red precipitate|red precipitate]] (as opposed to [[wikt:white precepitate|white precepitate]] being the [[mercuric amidochloride]]).
{{See also|Maslama al-Majriti}}


In 1774, [[Joseph Priestley]] discovered that oxygen was released by heating mercuric oxide, although he did not identify the gas as [[oxygen]] (rather, Priestley called it "[[Phlogiston|dephlogisticated]] air," as that was the [[paradigm]] that he was working under at the time).<ref>{{cite book |last=Almqvist |first=Ebbe |title=History of Industrial Gases |url=https://books.google.com/?id=OI0fTJhydh4C&pg=PA23&dq=Joseph+Priestley+oxygen+mercury |format= |accessdate= |edition= |series= |year=2003 |publisher=Springer |isbn=978-0-306-47277-0 |chapter= |chapterurl= |quote= |page=23 }}</ref>
In 1774, [[Joseph Priestley]] discovered that oxygen was released by heating mercuric oxide, although he did not identify the gas as [[oxygen]] (rather, Priestley called it "[[Phlogiston|dephlogisticated]] air," as that was the [[paradigm]] that he was working under at the time).<ref>{{cite book |last=Almqvist |first=Ebbe |title=History of Industrial Gases |url=https://books.google.com/books?id=OI0fTJhydh4C&dq=Joseph+Priestley+oxygen+mercury&pg=PA23 |year=2003 |publisher=Springer |isbn=978-0-306-47277-0 |page=23}}</ref>


==Synthesis==
==Synthesis and reactions==
[[File:Montroydite.jpg|thumb|left|Montroydite structure (red atoms are oxygens)]]
[[File:Montroydite.jpg|thumb|left|Montroydite structure (red atoms are oxygen)]]
[[File:Cinnabar structure.jpg|thumb|left|[[Cinnabar]] structure]]
[[File:Cinnabar structure.jpg|thumb|left|[[Cinnabar]] structure]]


The red form of HgO can be made by heating Hg in oxygen at roughly 350&nbsp;°C, or by [[pyrolysis]] of [[mercury(II) nitrate|Hg(NO<sub>3</sub>)<sub>2</sub>]].<ref name = "Greenwood">{{Greenwood&Earnshaw}}</ref> The yellow form can be obtained by precipitation of aqueous Hg<sup>2+</sup> with alkali.<ref name = "Greenwood"/> The difference in color is due to particle size, both forms have the same structure consisting of near linear O-Hg-O units linked in zigzag chains with an Hg-O-Hg angle of 108°.<ref name = "Greenwood"/>
The red form of HgO can be made by heating Hg in oxygen at roughly 350&nbsp;°C, or by [[pyrolysis]] of [[mercury(II) nitrate|Hg(NO<sub>3</sub>)<sub>2</sub>]].<ref name = "Greenwood">{{Greenwood&Earnshaw}}</ref> The yellow form can be obtained by precipitation of aqueous Hg<sup>2+</sup> with alkali.<ref name = "Greenwood"/> The difference in color is due to particle size; both forms have the same structure consisting of near linear O-Hg-O units linked in zigzag chains with an Hg-O-Hg angle of 108°.<ref name = "Greenwood"/>

It is sometimes said that HgO "is soluble in acids",<ref>{{cite web |title=Characteristic Reactions of Mercury Ions (Hg²⁺ and Hg₂²⁺) |url=https://chem.libretexts.org/Bookshelves/Analytical_Chemistry/Supplemental_Modules_(Analytical_Chemistry)/Qualitative_Analysis/Characteristic_Reactions_of_Select_Metal_Ions/Characteristic_Reactions_of_Mercury_Ions_(Hg_and_Hg) |website=LibreTextsChemistry |access-date=23 July 2024}}</ref> but in fact it reacts with acids to make mercuric salts.


==Structure==
==Structure==
Under atmospheric pressure mercuric oxide has two crystalline forms: one is called montroydite ([[orthorhombic]], 2/m 2/m 2/m, Pnma), and the second is analogous to the sulfide mineral [[cinnabar]] ([[Hexagonal crystal system|hexagonal]],
Under atmospheric pressure mercuric oxide has two crystalline forms: one is called montroydite ([[orthorhombic]], 2/m 2/m 2/m, Pnma), and the second is analogous to the sulfide mineral [[cinnabar]] ([[Hexagonal crystal system|hexagonal]],
hP6, P3221); both are characterized by Hg-O chains.<ref>{{Cite journal | last1 = Aurivillius | first1 = Karin | last2 = Carlsson | first2 = Inga-Britt | last3 = Pedersen | first3 = Christian | last4 = Hartiala | first4 = K. | last5 = Veige | first5 = S. | last6 = Diczfalusy | first6 = E. | title = The Structure of Hexagonal Mercury(II)oxide | journal = Acta Chemica Scandinavica | volume = 12 | pages = 1297–1304 | year = 1958 | url = http://actachemscand.dk/volume.php?select1=2&vol=12 | doi = 10.3891/acta.chem.scand.12-1297 | access-date = November 17, 2010| doi-access = free}}</ref> At pressures above 10 GPa both structures convert to a [[tetragonal]] form.<ref name=landolt/>
hP6, P3221); both are characterized by Hg-O chains.<ref>{{Cite journal
| last1 = Aurivillius
| first1 = Karin
| last2 = Carlsson
| first2 = Inga-Britt
| last3 = Pedersen
| first3 = Christian
| last4 = Hartiala
| first4 = K.
| last5 = Veige
| first5 = S.
| last6 = Diczfalusy
| first6 = E.
| title = The Structure of Hexagonal Mercury(II)oxide.
| journal = Acta Chemica Scandinavica
| volume = 12
| issue =
| pages = 1297–1304
| year = 1958
| url = http://actachemscand.dk/volume.php?select1=2&vol=12
| issn =
| doi = 10.3891/acta.chem.scand.12-1297
| id =
| accessdate = November 17, 2010| doi-access = free
}}</ref> At pressures above 10 GPa both structures convert to a [[tetragonal]] form.<ref name=landolt/>


==Uses==
==Uses==
[[Mercury (element)|Hg]][[oxygen|O]] is sometimes used in the production of mercury as it decomposes quite easily. When it decomposes, oxygen gas is generated.
Mercury oxide is sometimes used in the production of mercury as it decomposes quite easily. When it decomposes, oxygen gas is generated.{{citation needed|date=September 2023}}


It is also used as a material for [[cathode]]s for [[mercury battery|mercury batteries]].<ref>{{cite book |last=Moore |first=John W. |authorlink= |author2=Conrad L. Stanitski |author3=Peter C. Jurs |editor= |title=Chemistry: The Molecular Science |url=https://archive.org/details/chemistrymolecul0000moor |url-access=registration |quote=Mercury(II) oxide anode mercury battery. |format= |accessdate= |edition= |series= |year=2005 |publisher=Thomson Brooks/Cole |location= |language= |isbn=978-0-534-42201-1 |oclc= |doi= |id= |chapter= |chapterurl= |page=[https://archive.org/details/chemistrymolecul0000moor/page/941 941] }}</ref>
It is also used as a material for [[cathode]]s in [[mercury battery|mercury batteries]].<ref>{{cite book |last=Moore |first=John W. |author2=Conrad L. Stanitski |author3=Peter C. Jurs |title=Chemistry: The Molecular Science |url=https://archive.org/details/chemistrymolecul0000moor |url-access=registration |quote=Mercury(II) oxide anode mercury battery. |year=2005 |publisher=Thomson Brooks/Cole |isbn=978-0-534-42201-1 |page=[https://archive.org/details/chemistrymolecul0000moor/page/941 941]}}</ref>


==Health issues==
==Health issues==
[[File:HgOlabel.jpg|thumb|left|The label on an HgO powder bottle.]]
[[File:HgOlabel.jpg|thumb|left|The label on an HgO powder bottle.]]
Mercury oxide is a highly toxic substance which can be absorbed into the body by inhalation of its aerosol, through the skin and by ingestion. The substance is irritating to the eyes, the skin and the respiratory tract and may have effects on the kidneys, resulting in kidney impairment. In the food chain important to humans, [[bioaccumulation]] takes place, specifically in aquatic organisms. The substance is banned as a pesticide in the [[European Union|EU]].<ref name=bnpuk>{{cite web
Mercury oxide is a highly toxic substance which can be absorbed into the body by inhalation of its aerosol, through the skin and by ingestion. The substance is irritating to the eyes, the skin and the respiratory tract and may have effects on the kidneys, resulting in kidney impairment. In the food chain important to humans, [[bioaccumulation]] takes place, specifically in aquatic organisms. The substance is banned as a pesticide in the [[European Union|EU]].<ref name=bnpuk>{{cite web | last = Chemicals Regulation Directorate | title = Banned and Non-Authorised Pesticides in the United Kingdom | url = http://www.pesticides.gov.uk/approvals.asp?id=55 | access-date = 1 December 2009}}</ref>
| last = Chemicals Regulation Directorate
| authorlink =
| title = Banned and Non-Authorised Pesticides in the United Kingdom
| website =
| publisher =
| url = http://www.pesticides.gov.uk/approvals.asp?id=55
| doi =
| accessdate = 1 December 2009}}</ref>


Evaporation at 20&nbsp;°C is negligible. HgO decomposes on exposure to light or on heating above 500&nbsp;°C. Heating produces highly toxic mercury fumes and oxygen, which increases the fire hazard. Mercury(II) oxide reacts violently with reducing agents, chlorine, hydrogen peroxide, magnesium (when heated), disulfur dichloride and hydrogen trisulfide. Shock-sensitive compounds are formed with metals and elements such as sulfur and phosphorus.<ref>{{cite web| url = http://www.inchem.org/documents/icsc/icsc/eics0981.htm| title = Mercury (II) oxide| accessdate = 2009-06-06| publisher = International Occupational Safety and Health Information Centre}}</ref>
Evaporation at 20&nbsp;°C is negligible. HgO decomposes on exposure to light or on heating above 500&nbsp;°C. Heating produces highly toxic mercury fumes and oxygen, which increases the fire hazard. Mercury(II) oxide reacts violently with reducing agents, chlorine, hydrogen peroxide, magnesium (when heated), disulfur dichloride and hydrogen trisulfide. Shock-sensitive compounds are formed with metals and elements such as sulfur and phosphorus.<ref>{{cite web| url = http://www.inchem.org/documents/icsc/icsc/eics0981.htm| title = Mercury (II) oxide| access-date = 2009-06-06| publisher = International Occupational Safety and Health Information Centre}}</ref>


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{{Oxides}}
{{Oxides}}
{{oxygen compounds}}
{{oxygen compounds}}
{{Authority control}}


[[Category:Oxides]]
[[Category:Oxides]]

Latest revision as of 22:24, 23 July 2024

Mercury(II) oxide
Mercury(II) oxide
Mercury(II) oxide
Names
IUPAC name
Mercury(II) oxide
Other names
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.040.580 Edit this at Wikidata
KEGG
RTECS number
  • OW8750000
UNII
UN number 1641
  • InChI=1S/Hg.O checkY
    Key: UKWHYYKOEPRTIC-UHFFFAOYSA-N checkY
  • [Hg]=O
Properties
HgO
Molar mass 216.591 g·mol−1
Appearance Yellow or red solid
Odor odorless
Density 11.14 g/cm3
Melting point 500 °C (932 °F; 773 K) (decomposes)
0.0053 g/100 mL (25 °C)
0.0395 g/100 mL (100 °C)
Solubility insoluble in alcohol, ether, acetone, ammonia
Band gap 2.2 eV[1]
−44.0·10−6 cm3/mol
2.5 (550 nm)[1]
Thermochemistry
70 J·mol−1·K−1[2]
−90 kJ·mol−1[2]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Extremely toxic, environmental pollutant
GHS labelling:[4]
GHS06: Toxic GHS08: Health hazard GHS09: Environmental hazard
Danger
H300+H310+H330, H372, H410
P260, P262, P264, P270, P271, P273, P280, P284, P301+P316, P302+P352, P304+P340, P316, P320, P321, P330, P361+P364, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)
[5]
NFPA 704 four-colored diamondHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
4
0
1
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
18 mg/kg (oral, rat)[3]
Safety data sheet (SDS) ICSC 0981
Related compounds
Other anions
 Mercury sulfide
Mercury selenide
Mercury telluride
Other cations
 Zinc oxide
Cadmium oxide
Related compounds
 Mercury(I) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Mercury(II) oxide, also called mercuric oxide or simply mercury oxide, is the inorganic compound with the formula HgO. It has a red or orange color. Mercury(II) oxide is a solid at room temperature and pressure. The mineral form montroydite is very rarely found.

History

[edit]

An experiment for the preparation of mercuric oxide was first described by 11th century Arab-Spanish alchemist, Maslama al-Majriti, in Rutbat al-hakim.[6] It was historically called red precipitate (as opposed to white precepitate being the mercuric amidochloride).

In 1774, Joseph Priestley discovered that oxygen was released by heating mercuric oxide, although he did not identify the gas as oxygen (rather, Priestley called it "dephlogisticated air," as that was the paradigm that he was working under at the time).[7]

Synthesis and reactions

[edit]
Montroydite structure (red atoms are oxygen)
Cinnabar structure

The red form of HgO can be made by heating Hg in oxygen at roughly 350 °C, or by pyrolysis of Hg(NO3)2.[8] The yellow form can be obtained by precipitation of aqueous Hg2+ with alkali.[8] The difference in color is due to particle size; both forms have the same structure consisting of near linear O-Hg-O units linked in zigzag chains with an Hg-O-Hg angle of 108°.[8]

It is sometimes said that HgO "is soluble in acids",[9] but in fact it reacts with acids to make mercuric salts.

Structure

[edit]

Under atmospheric pressure mercuric oxide has two crystalline forms: one is called montroydite (orthorhombic, 2/m 2/m 2/m, Pnma), and the second is analogous to the sulfide mineral cinnabar (hexagonal, hP6, P3221); both are characterized by Hg-O chains.[10] At pressures above 10 GPa both structures convert to a tetragonal form.[1]

Uses

[edit]

Mercury oxide is sometimes used in the production of mercury as it decomposes quite easily. When it decomposes, oxygen gas is generated.[citation needed]

It is also used as a material for cathodes in mercury batteries.[11]

Health issues

[edit]
The label on an HgO powder bottle.

Mercury oxide is a highly toxic substance which can be absorbed into the body by inhalation of its aerosol, through the skin and by ingestion. The substance is irritating to the eyes, the skin and the respiratory tract and may have effects on the kidneys, resulting in kidney impairment. In the food chain important to humans, bioaccumulation takes place, specifically in aquatic organisms. The substance is banned as a pesticide in the EU.[12]

Evaporation at 20 °C is negligible. HgO decomposes on exposure to light or on heating above 500 °C. Heating produces highly toxic mercury fumes and oxygen, which increases the fire hazard. Mercury(II) oxide reacts violently with reducing agents, chlorine, hydrogen peroxide, magnesium (when heated), disulfur dichloride and hydrogen trisulfide. Shock-sensitive compounds are formed with metals and elements such as sulfur and phosphorus.[13]

References

[edit]
  1. ^ a b c Madelung, O; Rössler, U; Schulz, M, eds. (1999). "Mercury oxide (HgO) crystal structure, physical properties". Semiconductors · II-VI and I-VII Compounds; Semimagnetic Compounds. Landolt-Börnstein - Group III Condensed Matter. Vol. 41B. Springer-Verlag. pp. 1–7. doi:10.1007/b71137. ISBN 978-3-540-64964-9.
  2. ^ a b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A22. ISBN 978-0-618-94690-7.
  3. ^ "Mercuric oxide [ISO]". ChemIDPlus Advanced. United States National Library of Medicine. CAS RN: 21908-53-2. Retrieved 2022-04-14.
  4. ^ "Laboratory Chemical Safety Summary (LCSS): Mercuric oxide". PubChem. National Center for Biotechnology Information. CID 30856. Retrieved 2022-04-14.
  5. ^ "Safety Data Sheet: Mercury(II) oxide" (PDF). Thermo Fisher Scientific. 2021-12-25. Cat No. AC316790000. Retrieved 2022-04-13.
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  9. ^ "Characteristic Reactions of Mercury Ions (Hg²⁺ and Hg₂²⁺)". LibreTextsChemistry. Retrieved 23 July 2024.
  10. ^ Aurivillius, Karin; Carlsson, Inga-Britt; Pedersen, Christian; Hartiala, K.; Veige, S.; Diczfalusy, E. (1958). "The Structure of Hexagonal Mercury(II)oxide". Acta Chemica Scandinavica. 12: 1297–1304. doi:10.3891/acta.chem.scand.12-1297. Retrieved November 17, 2010.
  11. ^ Moore, John W.; Conrad L. Stanitski; Peter C. Jurs (2005). Chemistry: The Molecular Science. Thomson Brooks/Cole. p. 941. ISBN 978-0-534-42201-1. Mercury(II) oxide anode mercury battery.
  12. ^ Chemicals Regulation Directorate. "Banned and Non-Authorised Pesticides in the United Kingdom". Retrieved 1 December 2009.
  13. ^ "Mercury (II) oxide". International Occupational Safety and Health Information Centre. Retrieved 2009-06-06.
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