Sodium disulfate

Structural formula
General
Surname	Sodium disulfate
other names	Sodium pyrosulfate
Molecular formula	Na 2 S 2 O 7
Brief description	colorless, crystalline solid
External identifiers / databases
CAS number 13870-29-6 EC number 237-625-5 ECHA InfoCard 100.034.190 PubChem 9794487 ChemSpider 7970254 Wikidata Q425193
properties
Molar mass	222.16 g mol −1
Physical state	firmly
density	2.66 g cm −3 (at 20 ° C)
Melting point	402 ° C
safety instructions
GHS labeling of hazardous substances no GHS pictograms H and P phrases H: no H-phrases P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Sodium disulfate , also known as sodium pyrosulfate , is the disodium salt of disulfuric acid .

presentation

The chemical compound with the empirical formula Na ₂ S ₂ O ₇ is created when sodium hydrogen sulphate is heated with elimination of water:

${\displaystyle \mathrm {2\ NaHSO_{4}\ {\xrightarrow {\triangle }}\ Na_{2}S_{2}O_{7}\ +\ H_{2}O} }$

Another possibility of synthesis is the treatment of sodium sulfate with sulfur trioxide .

${\displaystyle \mathrm {Na_{2}SO_{4}\ +\ SO_{3}\ \longrightarrow \ Na_{2}S_{2}O_{7}} }$

properties

The compound forms colorless, triclinic crystals , which melt at 402 ° C and decompose to sulfur trioxide and sodium sulfate when glowing.

${\displaystyle \mathrm {Na_{2}S_{2}O_{7}\ {\xrightarrow {\triangle }}\ Na_{2}SO_{4}\ +\ SO_{3}\uparrow } }$

The monosodium salt of disulfuric acid with the empirical formula NaHS ₂ O ₇ is unknown.

swell

1. ^ Sodium pyrosulfate at the Commission de la santé et de la sécurité du travail in Québec .
2. ↑ ^{a b} R. Blachnik, J. D'Ans, E. Lax, C. Synowietz: Pocket book for chemists and physicists: Volume 3: Elements, inorganic compounds and materials, minerals. Springer, 1998, ISBN 9783540600350 .
3. ↑ SB Rasmussen, KM Eriksen, G. Hatem, F. da Silva, K. Ståhl, R. Fehrmann: Conductivity, Thermal Measurements, X-ray Investigations, and Phase Diagram of the Na ₂ S ₂ O ₇ -K ₂ S ₂ O ₇ system. In: The Journal of Physical Chemistry B. 105, 2001, pp. 2747-2752, doi : 10.1021 / jp0039262 .
4. ↑ There is not yet a harmonized classification for this substance . A labeling of disodium disulphate in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), which was retrieved on July 29, 2019, is reproduced from a self-classification by the distributor .
5. ^ ^{A b} R. Abegg, F. Auerbach, I. Koppel: Handbook of inorganic chemistry . Verlag S. Hirzel, 1908, 2nd volume, 1st part, p. 272. Full text
6. ^ Research in the Chemical Abstracts database of October 16, 2008.