Sodium pyrosulfate

Sodium pyrosulfate is an inorganic compound with the chemical formula of Na2S2O7.[1] It is a colorless salt.[3]

Sodium pyrosulfate[1]
IUPAC name
Disodium disulfate
Other names
Sodium pyrosulphate; Disulfuric acid disodium salt, disodium disulfate
3D model (JSmol)
ECHA InfoCard 100.034.190
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)
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


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

2 NaHSO4 → Na2S2O7 + H2O

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

Na2S2O7 → Na2SO4 + SO3


Sodium pyrosulfate was used in analytical chemistry. Samples are fused with sodium pyrosulfate to ensure complete dissolution before a quantitative analysis.[5][6]

See also


  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. 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.
  6. 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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