pKa Suite Calculator
Complete acid-base ionization and pKa calculations
Acid-Base Chemistry
pKa Suite Tools
Display Format
Acid Dissociation Constant
Enter as decimal or scientific notation
pKₐ = -log₁₀(Kₐ)
Formulas
pKₐ = -log₁₀(Kₐ)
Where Kₐ is the acid dissociation constant
Example Acids
pKₐ Result
Calculated Value
Enter Values
Acid Strength Guide
Strong acids:
pKₐ < 0 (HCl, H₂SO₄)
Moderate acids:
pKₐ 0-4 (Acetic acid)
Weak acids:
pKₐ 4-10 (Ammonium)
Very weak:
pKₐ < 10 (Water)
Acid-Base Principles
Kₐ and pKₐ
• Kₐ = [H⁺][A⁻]/[HA]
• pKₐ = -log₁₀(Kₐ)
• Larger Kₐ = stronger acid
• Smaller pKₐ = stronger acid
• pKₐ = pH when [HA] = [A⁻]
Ionization State
• pH < pKₐ: Predominantly HA
• pH = pKₐ: 50% ionized
• pH > pKₐ: Predominantly A⁻
• Affects solubility
• Affects membrane permeability
Applications
• Buffer preparation
• Drug absorption prediction
• Protein structure
• Analytical method development
• Solubility optimization