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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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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dissociation constant
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
according to guideline
other: Calculation method
Principles of method if other than guideline:
Theoretical calculation. Dissociation Constant of NiF2 is derived from pKa of hydrofluoric acid, HF, and of Nickel hydroxide, Ni(OH)2 and the correspondent water solubility.
Dissociating properties:
ca. 0.019
20 °C
Remarks on result:
other: Calculated

Dissociation constant was calculated.

pKa Hydrofluoric acid = 3.15

pKa Nickel hydroxide = 13.80

Nickel hydroxide value is very close to 14 indicating that it is a strong basis and the corresponent ion (Ni2 +) has no further equilibrium in solution.

pKa of hydrofluoric acid is only 3.15 indicating that it is rather a weak acid. Ion F- is prone to be in equilibrium with its undissociated form HF.

The calculated Ks for Nickel fluoride is 1.927exp-2, i.e. a pKa=0.01927

Description of key information

pKa 0.01927 at 20 °C

Key value for chemical safety assessment

pKa at 20°C:

Additional information

Calculated from pKa + water solubility of Hydrofluoric Acid and pKb + water solubility of Nickel hydroxide