Ka and pKa Converter
Ka and pKa converter
Convert between acid dissociation constant (Ka) and pKa.
Result
pKa = 4.74472749
Uses pKa = -log10(Ka).
Chem signal
Advanced options
Flow
- Choose conversion direction.
- Enter Ka or pKa value depending on mode.
- Use the converted constant in buffer or titration calculations.
Example
Worked example: Ka = 1.8×10^-5
- 1 pKa = -log10(1.8×10^-5)
- 2 pKa ≈ 4.7447
- 3 Reverse check: Ka = 10^-4.7447
Ka of 1.8×10^-5 corresponds to pKa of about 4.74.
How
- Choose conversion direction.
- Enter Ka or pKa value depending on mode.
- Use the converted constant in buffer or titration calculations.
Avoid
- Entering Ka values less than or equal to zero.
- Using natural log instead of base-10 logarithm.
- Forgetting that lower pKa means stronger acid in the same medium.
Checks
Best fit
Ka and pKa Converter is built for convert ka to pka or pka to ka for acid-base equilibrium analysis. If Ka and pKa Converter does not match the input scope, compare the answer with a second method.
Input check
Match the entered values to this rule before copying the answer: pKa = -log10(Ka), Ka = 10^(-pKa).
Sanity check
For Ka and pKa Converter, use the worked example as a quick benchmark: Ka of 1.8×10^-5 corresponds to pKa of about 4.74. If the ka and pka converter answer is far away, check whether an input, unit, or mode changed.
Before copying
Review this common issue first: entering ka values less than or equal to zero.
FAQ
Can pKa be negative?
Yes, strong acids can have negative pKa values.
Why does Ka need to be positive?
Ka is an equilibrium constant and must be greater than zero.
Is this temperature corrected?
No. Use constants measured at your working temperature when available.
Switch
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No match.