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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

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Environmental fate & pathways


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Description of key information

The substance undergoes dissociation and hydrolysis in aqueous solution. The overall reaction is highly influenced by pH. However, at environmental pH, the substance is completely hydrolysed to fluoride.

Key value for chemical safety assessment

Additional information

Disodium hexafluorosilicate undergoes dissociation and hydrolysis, providing the following overall reaction:

Na2SiF6+ 4H2O → 6NaF + Si(OH)4

The extent that it occurs depends highly on the pH, since although dissociation of salts readily occurs in aqueous solution, hydrolysis is very much influenced by pH. However, at environmental pH, hydrolysis is complete affording 100% fluoride.