Sodium pyrosulfate

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Sodium pyrosulfate
Names
IUPAC name
Disodium disulfate
Other names
Disulfuric acid disodium salt
Sodium disulfate
Sodium pyrosulphate
Identifiers
Jmol-3D images Image
Properties
Na2S2O7
Molar mass 222.12 g/mol
Appearance White crystalline solid
Density 2.658 g/cm3
Melting point 400.9 °C (753.6 °F; 674.0 K)
Boiling point 460 °C (860 °F; 733 K) (decomposition)
Thermochemistry
-1,717.6--1,907 kJ/mol
Hazards
Related compounds
Related compounds
Sodium bisulfate
Sodium metabisulfite
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Sodium pyrosulfate (also known as disodium disulfate) is a sodium salt of disulfuric acid, with the formula Na2S2O7.

Properties

Chemical

Sodium pyrosulfate decomposes when heated above 460 °C to give sodium sulfate and sulfur trioxide:

Na2S2O7 → Na2SO4 + SO3

This reaction is a convenient way of obtaining sulfur trioxide, as it does not require complex installation and the pyrosulfate precursor, sodium bisulfate, is readily available.

Physical

Sodium disulfate is a white salt, soluble in water.

Availability

Sodium pyrosulfate is rarely available from suppliers. Sigmaaldrich used to sell sodium disulfate fused with sodium bisulfate.

Preparation

Sodium pyrosulfate can be easily made by heating sodium bisulfate at temperatures between 200-400 °C:

2 NaHSO4 → Na2S2O7 + H2O

However, other authors indicate different temperature decomposition ranges.[1]

Projects

  • Make sulfur trioxide
  • Make ammonium pyrosulfate

Handling

Safety

Storage

In closed bottles.

Disposal

References

  1. http://doc.utwente.nl/68103/1/Vries69thermal.pdf

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