pKa Calculator
Calculate pKa from Ka or using Henderson-Hasselbalch
Results
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Henderson-Hasselbalch Equation:
pKa = pH + log([A⁻]/[HA])
Understanding pKa
The pKa value is a measure of acid strength. It is the negative logarithm (base 10) of the acid dissociation constant (Ka). Lower pKa values indicate stronger acids. The Henderson-Hasselbalch equation relates pH, pKa, and the ratio of conjugate base to acid.
Common pKa Values
Hydrochloric Acid (HCl)pKa = -7
Acetic AcidpKa = 4.76
Carbonic AcidpKa = 6.35
AmmoniumpKa = 9.25
WaterpKa = 15.7