Mercury sulfide

Mercury sulfide, mercuric sulfide, mercury sulphide, or mercury(II) sulfide is a chemical compound composed of the chemical elements mercury and sulfur. It is represented by the chemical formula HgS. It is virtually insoluble in water.[4]

Mercury sulfide
Names
IUPAC name
Mercury sulfide
Other names
Identifiers
CAS Number
ECHA InfoCard 100.014.270
PubChem CID
UNII
CompTox Dashboard (EPA)
Properties
Chemical formula
 HgS
Molar mass 232.66 g/mol
Density 8.10 g/cm3
Melting point 580 °C (1,076 °F; 853 K) decomposes
Solubility in water
 insoluble
Band gap 2.1 eV (direct, α-HgS) [1]
Magnetic susceptibility (χ)
 −55.4·10−6 cm3/mol
Refractive index (nD)
 w=2.905, e=3.256, bire=0.3510 (α-HgS) [2]
Thermochemistry
Std molar
entropy (So298)
 78 J·mol−1·K−1[3]
Std enthalpy of
formation (ΔfH⦵298)
 −58 kJ·mol−1[3]
Hazards
Safety data sheet ICSC 0981
EU classification (DSD) (outdated)
 Very toxic (T+)
Dangerous for the environment (N)
R-phrases (outdated) R26/27/28, R33, R50/53
S-phrases (outdated) (S1/2), S13, S28, S45, S60, S61
NFPA 704 (fire diamond)
1
3
0
Flash point Non-flammable
Related compounds
Other anions
 Mercury oxide
Mercury selenide
Mercury telluride
Other cations
 Zinc sulfide
Cadmium sulfide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Crystal structure
Cinnabar from Nevada, US

HgS is dimorphic with two crystal forms:

  • red cinnabar (α-HgS, trigonal, hP6, P3221), is the form in which mercury is most commonly found in nature.
  • black, metacinnabar (β-HgS), is less common in nature and adopts the zinc blende (T2d-F43m) crystal structure.

Crystals of red, α-HgS, are optically active. This is caused by the Hg-S helices in the structure.[5]

Preparation and chemistry

β-HgS is precipitated as a black powder when H2S is bubbled through solutions of Hg(II) salts.[6] β-HgS is unreactive to all but concentrated acids.[4]
Mercury metal is produced from the cinnabar ore by roasting in air and condensing the vapour.[4]

Uses

When α-HgS is used as a red pigment, it is known as vermilion. The tendency of vermilion to darken has been ascribed to conversion from red α-HgS to black β-HgS. However β-HgS was not detected at excavations in Pompeii, where originally red walls darkened, and was attributed to the formation of Hg-Cl compounds (e.g., corderoite, calomel, and terlinguaite) and calcium sulfate, gypsum.[7]

As the mercury cell as used in the chlor-alkali industry (Castner–Kellner process) is being phased out over concerns over mercury emissions, the metallic mercury from these setups is converted into mercury sulfide for underground storage.

See also
  • Mercury poisoning
  • Mercury(I) sulfide (mercurous sulfide), Hg
    2    S

References
  1. L. I. Berger, Semiconductor Materials (1997) CRC Press ISBN 0-8493-8912-7
  2. Webminerals
  3. Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A22. ISBN 0-618-94690-X.
  4. Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. p. 1406. ISBN 978-0-08-022057-4.
  5. A. M. Glazer, K. Stadnicka (1986). "On the origin of optical activity in crystal structures". J. Appl. Cryst. 19 (2): 108–122. doi:10.1107/S0021889886089823.
  6. Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999), Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, ISBN 0-471-19957-5
  7. Cotte, M; Susini J; Metrich N; Moscato A; Gratziu C; Bertagnini A; Pagano M (2006). "Blackening of Pompeian Cinnabar Paintings: X-ray Microspectroscopy Analysis". Anal. Chem. 78 (21): 7484–7492. doi:10.1021/ac0612224. PMID 17073416.