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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

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.

Diss Factsheets

Physical & Chemical properties

Dissociation constant

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Administrative data

Link to relevant study record(s)

Reference
Endpoint:
dissociation constant
Type of information:
other: handbook data
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Adopted according to OECD SIDS or other official EU regulatory procedures (public available peer reviewed source)
Principles of method if other than guideline:
Handbook data, no information on test details.
GLP compliance:
no
Dissociating properties:
yes
No.:
#1
pKa:
>= 9.9 - <= 12
Temp.:
30 °C

Consideration of the high dissociation constants of silicic acid (pKa 9.9, 11.8, 12 at 30 °C) leads to the conclusion that at environmental pH values of 6.5 ¿ 8.5 only a small proportion of silicate ions will be in solution.

Description of key information

pKa 9.9, 11.8, 12 at 30 °C

Key value for chemical safety assessment

Additional information

Consideration of the high dissociation constants of silicic acid leads to the conclusion that at environmental pH values of 6.5 ¿ 8.5 only a small proportion of silicate ions will be in solution (Lide & Frederikse 1995).