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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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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Reference
Endpoint:
dissociation constant
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
The dissociation constant study was not conducted for the substance itself, as the substance is a water soluble inorganic salt. Dissociation of such a salt in water means splitting into ionic species (anions and cations). Determination of a pKa value is therefore not applicable. The pKa was determined for the anions and cations individually.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Method followed unknown; data from handbook.
GLP compliance:
not specified
Dissociating properties:
yes
No.:
#1
pKa:
-1.4
Temp.:
25 °C
Remarks on result:
other: Nitric acid
No.:
#2
pKa:
9.25
Temp.:
25 °C
Remarks on result:
other: Ammonium
No.:
#3
pKa:
12.6
Temp.:
25 °C
Remarks on result:
other: Calcium (II) ion

Description of key information

The dissociation constant study was not conducted for the substance itself, as the substance is a water soluble inorganic salt. Dissociation of such a salt in water means splitting into ionic species (anions and cations). Determination of a pKa value is therefore not applicable. The pKa at 25°C for the anions and cations were described in the CRC handbook as follows:

Nitric acid: -1.4

Ammonium: 9.25

Calcium (II) ion: 12.6

Key value for chemical safety assessment

Additional information