Mercury(I) sulfate

Mercury(I) sulfate
Names
	IUPAC name Mercury(I) sulfate
	Other names Mercurous sulfate
Identifiers
CAS Number	7783-36-0 ;
3D model (JSmol)	Interactive image;
ChemSpider	22951 ;
ECHA InfoCard	100.029.084
EC Number	231-993-0;
PubChem CID	24545;
UNII	PI950N9DYS ;
CompTox Dashboard (EPA)	DTXSID9074565 ;
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Properties
Chemical formula	Hg2SO4
Molar mass	497.24 g/mol
Appearance	whitish-yellow crystals
Density	7.56 g/cm3
Solubility in water	0.051 g/100 mL (25 °C) ; 0.09 g/100 mL (100 °C)
Solubility	soluble in dilute nitric acid, Insoluble in water, Soluble in hot sulfuric acid.
Magnetic susceptibility (χ)	−123.0·10−6 cm3/mol
Structure
Coordination geometry	monoclinic
Thermochemistry
Heat capacity (C)	132 J·mol−1·K−1
Std molar; entropy (So298)	200.7 J·mol−1·K−1
Std enthalpy of; formation (ΔfH⦵298)	-743.1 kJ·mol−1
Related compounds
Other anions	Mercury(I) fluoride; Mercury(I) chloride; Mercury(I) bromide; Mercury(I) iodide
Other cations	Mercury(II) sulfate; Cadmium sulfate; Thallium(I) sulfate
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	(what is ?)
	Infobox references

Mercury(I) sulfate, commonly called mercurous sulphate (UK) or mercurous sulfate (US) is the chemical compound Hg₂SO₄.^[2] Mercury(I) sulfate is a metallic compound that is a white, pale yellow or beige powder.^[3] It is a metallic salt of sulfuric acid formed by replacing both hydrogen atoms with mercury(I). It is highly toxic; it could be fatal if inhaled, ingested, or absorbed by skin.

Structure[]

The crystal structure of mercurous sulfate is made up of Hg₂²⁺ dumbbells^{[clarification needed]} and SO₄²⁻ anions as main building units. Hg₂²⁺ dumbbell is surrounded by four oxygen atoms, with the Hg-O distance ranging from 2.23 to 2.93 Å, whereas the Hg-Hg distance is about 2.50 Å.^[4]

Studies have shown mercury(I) sulfate to have the mercury atoms arranged in doublets with a bond distance of 2.500 Å. The metal atom doublets are oriented parallel to the an axis^{[clarification needed]} in a unit cell. Mercury doublets form part of an infinite chain: SO₄ – Hg – Hg – SO₄ – Hg – Hg – ... The Hg – Hg – O bond angle is 165°±1°. The chain crosses the unit cell diagonally. The mercury sulfate structure is held together by weak Hg-O interactions. The SO₄ does not act as a single anion, but rather is coordinated to the mercury metal.^[5]

Preparation[]

One way to prepare mercury(I) sulfate is to mix the acidic solution of mercury(I) nitrate with 1 to 6 sulfuric acid solution:,^[6]^[7]

Hg₂(NO₃)₂ + H₂SO₄ → Hg₂SO₄ + 2 HNO₃

It can also be prepared by reacting an excess of mercury with concentrated sulfuric acid:^[6]

2 Hg + 2 H₂SO₄ → Hg₂SO₄ + 2 H₂O + SO₂

Use in electrochemical cells[]

Mercury(I) sulfate is often used in electrochemical cells.^[8]^[9]^[10] It was first introduced in electrochemical cells by Latimer Clark in 1872,^[11] It was then alternatively^{[clarification needed]} used in Weston cells made by George Augustus Hulett in 1911.^[11] It has been found to be a good electrode at high temperatures above 100 °C along with silver sulfate.^[12]

Mercury(I) sulfate has been found to decompose at high temperatures. The decomposition process is endothermic, and it occurs between 335°C and 500°C.

Mercury(I) sulfate has unique properties that make the standard cells possible. It has a rather low solubility (about one gram per liter); diffusion from the cathode system is not excessive; and it is sufficient to give a large potential at a mercury electrode.^[13]

References[]

^ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 5–19, ISBN 0-8493-0594-2
^ Intermediate Inorganic Chemistry by J. W. Mellor, published by Longmans, Green and Company, London, 1941, page 388
^ http://www.chemicalbook.com/ChemicalProductProperty_EN_CB0259783.htm
^ Preparation and Characterization of Dimercury(I)Monofluorophosphate(V), Hg₂PO₃F: Crystal Structure, Thermal Behavior, Vibrational Spectra, and Solid-State ³¹P and ¹⁹F NMR Spectra by Matthias Weil, Michael Puchberger, and Enrique J. Baran, published by Inorg. Chem. 2004, 43. pages 8330–8335
^ Dorm, E. 1969. Structural studies on mercury(I) compounds. VI. Crystal structure of mercury(I) sulfate and selenate. Acta Chemica Scandinavica (1947–1973) 23:1607–15.
^ Jump up to: ^a ^b Google Books result, accessed 11 December 2010
^ Mercurous Sulphate, cadmium sulphate, and the cadmium cell. by Hulett G. A. The physical review.1907. p.19.
^ "Influence of Microstucture on the Charge Storage Properties of Chemically Synthesized Manganese Dioxide" by Mathieu Toupin, Thiery Brousse, and Daniel Belanger. Chem. Mater. 2002, 14, 3945–3952
^ "Electromotive Force Studies of Cell, Cd_xHg_y | CdSO₄,(m) I Hg₂SO₄, Hg, in Dioxane-Water Media" by Somesh Chakrabarti and Sukumar Aditya. Journal of Chemical and Engineering Data, Vol.17, No. 1, 1972
^ "Characterization of Lithium Sulfate as an Unsymmetrical-Valence Salt Bridge for the Minimization of Liquid Junction Potentials in Aqueous – Organic Solvent Mixtures" by Cristiana L. Faverio, Patrizia R. Mussini, and Torquato Mussini. Anal. Chem. 1998, 70, 2589–2595
^ Jump up to: ^a ^b "George Augustus Hulett: from Liquid Crystals to Standard Cell" by John T. Stock. Bull. Hist. Chem. Volume 25, Number 2, 2000, p.91-98
^ Lietzke, M. H.; Stoughton, R. W. (November 1953). "The Behavior of the Silver—Silver Sulfate and the Mercury—Mercurous Sulfate Electrodes at High Temperatures 1". Journal of the American Chemical Society. 75 (21): 5226–5227. doi:10.1021/ja01117a024.(subscription required)
^ "Sulphates of Mercury and Standard Cells." by Elliott, R. B. and Hulett, G. A. The Journal of Physical Chemistry 36.7 (1932): 2083–2086.

[hand2-1] Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 5–19, ISBN 0-8493-0594-2

[2] Intermediate Inorganic Chemistry by J. W. Mellor, published by Longmans, Green and Company, London, 1941, page 388

[3] ttp://www.chemicalbook.com/ChemicalProductProperty_EN_CB0259783.htm

[4] Preparation and Characterization of Dimercury(I)Monofluorophosphate(V), Hg₂PO₃F: Crystal Structure, Thermal Behavior, Vibrational Spectra, and Solid-State ³¹P and ¹⁹F NMR Spectra by Matthias Weil, Michael Puchberger, and Enrique J. Baran, published by Inorg. Chem. 2004, 43. pages 8330–8335

[5] Dorm, E. 1969. Structural studies on mercury(I) compounds. VI. Crystal structure of mercury(I) sulfate and selenate. Acta Chemica Scandinavica (1947–1973) 23:1607–15.

[google-6] Jump up to: ^a ^b Google Books result, accessed 11 December 2010

[7] Mercurous Sulphate, cadmium sulphate, and the cadmium cell. by Hulett G. A. The physical review.1907. p.19.

[8] "Influence of Microstucture on the Charge Storage Properties of Chemically Synthesized Manganese Dioxide" by Mathieu Toupin, Thiery Brousse, and Daniel Belanger. Chem. Mater. 2002, 14, 3945–3952

[9] "Electromotive Force Studies of Cell, Cd_xHg_y | CdSO₄,(m) I Hg₂SO₄, Hg, in Dioxane-Water Media" by Somesh Chakrabarti and Sukumar Aditya. Journal of Chemical and Engineering Data, Vol.17, No. 1, 1972

[10] "Characterization of Lithium Sulfate as an Unsymmetrical-Valence Salt Bridge for the Minimization of Liquid Junction Potentials in Aqueous – Organic Solvent Mixtures" by Cristiana L. Faverio, Patrizia R. Mussini, and Torquato Mussini. Anal. Chem. 1998, 70, 2589–2595

[GEORGE_AUGUSTUS_HULETT_2000,_p.91-98-11] Jump up to: ^a ^b "George Augustus Hulett: from Liquid Crystals to Standard Cell" by John T. Stock. Bull. Hist. Chem. Volume 25, Number 2, 2000, p.91-98

[12] Lietzke, M. H.; Stoughton, R. W. (November 1953). "The Behavior of the Silver—Silver Sulfate and the Mercury—Mercurous Sulfate Electrodes at High Temperatures 1". Journal of the American Chemical Society. 75 (21): 5226–5227. doi:10.1021/ja01117a024.(subscription required)

[13] "Sulphates of Mercury and Standard Cells." by Elliott, R. B. and Hulett, G. A. The Journal of Physical Chemistry 36.7 (1932): 2083–2086.

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