pKa to Ka Calculator
This pKa to Ka calculator helps chemists and students understand the strength of acids and their dissociation behavior in solutions.
The acetic acid (CH₃COOH) with a pKa value of 4.76. Using the calculator, we can find its Ka value: By inputting pKa = 4.76, the calculator computes Ka = 1.74 × 10⁻⁵, revealing that acetic acid is a weak acid with limited dissociation in water.
pKa to Ka Formula
The formula from pKa and Ka is expressed through a logarithmic equation:
pKa = -log₁₀(Ka)To find Ka from pKa:
Ka = 10⁻ᵖᴷᵃpKa to Ka Conversion Chart
| Acid Name | pKa Value | Ka Value |
|---|---|---|
| Hydrochloric Acid | -6.3 | 2.0 × 10⁶ |
| Sulfuric Acid | -3.0 | 1.0 × 10³ |
| Phosphoric Acid | 2.12 | 7.5 × 10⁻³ |
| Citric Acid | 3.13 | 7.4 × 10⁻⁴ |
| Acetic Acid | 4.76 | 1.74 × 10⁻⁵ |
| Carbonic Acid | 6.37 | 4.3 × 10⁻⁷ |
| Water | 14.0 | 1.0 × 10⁻¹⁴ |
How to calculate Ka from pKa?
pKa of formic acid (HCOOH) = 3.75
- Write the equation: Ka = 10⁻ᵖᴷᵃ
- Substitute the pKa value: Ka = 10⁻³·⁷⁵
- Calculate using a scientific calculator
- Result: Ka = 1.78 × 10⁻⁴
This value indicates that formic acid is a stronger acid than acetic acid but still falls within the weak acid category.
What is Ka and pKa?
Ka, the acid dissociation constant, quantifies an acid’s tendency to dissociate into ions in aqueous solutions. It represents the equilibrium constant for the acid-base reaction. Higher Ka values indicate stronger acids with greater dissociation.
pKa, the negative logarithm of Ka, offers a more manageable scale for comparing acid strengths.