Sodium pyrosulfate

Sodium pyrosulfate is an inorganic compound with the chemical formula of Na2S2O7.[1] It is a colorless salt.[3] It hydrolyses in water to form sodium bisulfate with a chemical formula of NaHSO4 which has a pH of around 1.

Sodium pyrosulfate[1]
Names
IUPAC name
Disodium disulfate
Other names
Sodium pyrosulphate; Disulfuric acid disodium salt, disodium disulfate; Sodium metabisulfate
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.034.190
EC Number
  • 237-625-5
  • InChI=1S/2Na.H2O7S2/c;;1-8(2,3)7-9(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2*+1;/p-2
    Key: JXAZAUKOWVKTLO-UHFFFAOYSA-L
  • [Na+].[Na+].[O-]S(=O)(=O)OS(=O)(=O)[O-]
Properties
Na2S2O7
Molar mass 222.12 g/mol
Appearance Translucent white crystals
Density 2.658 g/cm3
Melting point 400.9 °C (753.6 °F; 674.0 K)
Boiling point decomposes at 460 °C (860 °F; 733 K)
hydrolyses[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

It is usually prepared by the dehydration of sodium bisulfate into sodium pyrosulfate: 2NaHSO4 —> Na2S2O7 + H2O

Preparation

Sodium pyrosulfate is obtained by the dehydration of sodium bisulfate:[4][5]

2 NaHSO4 → Na2S2O7 + H2O

Temperatures above 460 °C further decompose the compound, producing sodium sulfate and sulfur trioxide:

Na2S2O7 → Na2SO4 + SO3

Applications

Sodium pyrosulfate was used in analytical chemistry. Samples are fused with sodium pyrosulfate to ensure complete dissolution before a quantitative analysis.[6][7]

See also

References
  1. Olsen, J. C., ed. (1934). Van Nostrand's Chemical Annual. London: Chapman and Hall.
  2. Heinz K. Hofmeister; John R. Van Wazer (1962). "Hydrolysis of Sodium Pyrosulfate". Inorganic Chemistry. ACS. 1 (4): 811–812. doi:10.1021/ic50004a019.
  3. Helmold Plessen (2000). "Sodium Sulfates". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a24_355. ISBN 978-3527306732.
  4. Noyes, William (1913). A Textbook of Chemistry. New York: Henry Holt and Company. p. 186. Retrieved 13 January 2016.
  5. von Plessen, Helmold (2000). "Sodium Sulfates". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a24_355. ISBN 9783527303854.
  6. Nemodruk, Aleksandr; Karalova, Zinaida (1969). Analytical chemistry of boron: Analytical chemistry of the elements. Charlottesville, VA: Ann Arbor-Humphrey Science Publishers. pp. 23 & 193. ISBN 9780250399192.
  7. Kiely, P. V.; Jackson, M. L. (1965). "Quartz, Feldspar, and Mica Determination for Soils by Sodium Pyrosulfate Fusion". Soil Science Society of America Journal. 29 (2): 159–163. Bibcode:1965SSASJ..29..159K. doi:10.2136/sssaj1965.03615995002900020015x.
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