Registration Dossier
Registration Dossier
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EC number: 223-888-3 | CAS number: 4109-96-0
Dissociation constant
Administrative data
Link to relevant study record(s)
Description of key information
Dissociation constant (dichlorosilane): Not relevant
Dissociation constant (silicic acid): pKa1 = 9.9
Key value for chemical safety assessment
Additional information
The requirement to conduct a dissociation constant study for dichlorosilane is waived because in contact with water the substance very rapidly hydrolyses to form silanediol as an intermediate hydrolysis product. The ultimate hydrolysis product is silicic acid.
Monosilicic acid was reported to have dissociation constant values of pKa1 = 9.9, pKa2 = 11.8, pKa3 and pKa4 = 12 at 30°C in a secondary data source which has been subject to peer review and in which the original sources are traceable. Monosilicic acid is therefore, an extremely weak acid. In neutral solution, the undissociated form will dominate.
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