Science & engineering
Weak acid buffer pH
Explore the Henderson–Hasselbalch model with a stated conjugate pair.
A clear answer. Here’s how.
For a suitable weak acid/conjugate base pair, pH≈pKa+log₁₀([base]/[acid]). Both concentrations refer to the same final solution. Reports their ratio and combined analytical concentration. This approximation assumes appropriate equilibrium conditions and neglects activity corrections; it does not infer a chemical pair, buffer capacity, reaction with added acid/base or biological interpretation.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Acid pKa
- 4.76
- Weak acid concentration (mol/L)
- 0.1
- Conjugate base concentration (mol/L)
- 0.1
Example result
- Approximate buffer pH
- 4.76
- Base / acid ratio
- 1
- Combined analytical concentration
- 0.2 mol/L