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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:
accepted calculation method
Qualifier:
according to guideline
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:
yes
No.:
#1
pKa:
ca. 0.019
Temp.:
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.

Conclusions:
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:
0.019

Additional information

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