Calculateur Acide-Base Conjugué
Identifiez les paires acide-base conjuguées et leurs constantes.
Conjugate K Value
0.0000
Formule
## Conjugate Acid-Base Relationship ### Formula **Ka × Kb = Kw** Therefore: - **Ka = Kw / Kb** (find Ka of conjugate acid from Kb of base) - **Kb = Kw / Ka** (find Kb of conjugate base from Ka of acid) At 25°C, Kw = 1.0 × 10⁻¹⁴. This means pKa + pKb = 14.
Exemple Résolu
Ammonia has Kb = 1.8 × 10⁻⁵. Find Ka of its conjugate acid NH₄⁺.
- 01Ka = Kw / Kb
- 02Ka = 1.0 × 10⁻¹⁴ / 1.8 × 10⁻⁵
- 03Ka = 5.56 × 10⁻¹⁰
- 04pKa = -log₁₀(5.56 × 10⁻¹⁰) = 9.26
Questions Fréquentes
What is a conjugate acid-base pair?
A conjugate pair differs by one proton (H⁺). When a base accepts a proton, it forms its conjugate acid. When an acid donates a proton, it forms its conjugate base.
Why does Ka × Kb = Kw?
The dissociation of the acid and the protonation of the base combine to give the autoionization of water: H₂O ⇌ H⁺ + OH⁻.
Does Kw change with temperature?
Yes. Kw = 1.0 × 10⁻¹⁴ at 25°C but increases with temperature (e.g., 5.5 × 10⁻¹³ at 100°C).
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