Registration Dossier
Registration Dossier
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 240-778-0 | CAS number: 16721-80-5
Hydrolysis
Administrative data
Link to relevant study record(s)
Description of key information
Na2S and NaHS are immediately hydrolyzed in aqueous environments, establishing an equilibrium between S2-, HS-, and H2S as a function of pH. In this respect, the Hägg graph is considered as key information.
Key value for chemical safety assessment
Additional information
In aqueous environments, Na2S and NaHS are immediately hydrolyzed and, as a function of pH, an equilibrium is established between S2-, HS-, and H2S, with increasing H2S formation with decreasing pH. H2S is an extremely toxic gas that can stay present in water for several hours, depending on the oxygen level of the environment under consideration. In oxic systems, oxidation to - eventually - sulfate will occur.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
