pKa Calculator
Calculate pKa
About pKa
pKa is the negative logarithm of the acid dissociation constant (Ka). It's a measure of acid strength, with lower pKa values indicating stronger acids.
pKa = -log(Ka)
Key relationships:
- pKa = -log(Ka)
- Ka = 10^(-pKa)
- pKa + pKb = 14 (for conjugate acid-base pairs)
- Lower pKa = stronger acid
From Gibbs Free Energy:
pKa = ΔG° / (2.303 × R × T)
Common pKa Values:
• HCl: -7
• CH₃COOH: 4.75
• NH₄⁺: 9.25
• H₂O: 15.7
pKa is essential in understanding acid-base chemistry, buffer systems, and predicting chemical reactivity.