pKa
| Formula / Notation | pKa = −log Ka; pKb = −log Kb; pKa + pKb = pKw = 14 (at 25°C) |
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| Also Known As | Acid dissociation constant (log form), pKa value, logarithmic Ka, −log Ka |
What is pKa?
The negative logarithm of the acid dissociation constant Ka: pKa = -log(Ka). A lower pKa indicates a stronger acid. The pKa is the pH at which an acid is exactly half-dissociated. It is used extensively in acid-base chemistry, buffer calculations, and drug design.
Formula & Notation
Other Names / Synonyms: Acid dissociation constant (log form), pKa value, logarithmic Ka, −log Ka
Properties & Characteristics
Uses & Applications
Safety Information
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
Key Facts
Frequently Asked Questions
The negative logarithm of the acid dissociation constant Ka: pKa = -log(Ka). A lower pKa indicates a stronger acid. The pKa is the pH at which an acid is exactly half-dissociated. It is used extensively in acid-base chemistry, buffer calculations, and drug design.
pKa values are used in: buffer design (choose acid with pKa near the desired buffer pH ± 1), predicting protonation state at physiological pH (important for drug bioavailability — charged vs. neutral form affects membrane permeability), reaction mechanism analysis (rationalising leaving group abilit…
pKa does not directly indicate toxicity, but it determines the fraction of a weak acid or base in its ionised vs. neutral form in biological systems. The pH-partition hypothesis: neutral forms cross membranes, but ionised forms are trapped in aqueous compartments. Understanding pKa helps predict dis…
The formula or notation for pKa is: pKa = −log Ka; pKb = −log Kb; pKa + pKb = pKw = 14 (at 25°C)