Result summary
Submit the form to calculate acid or base dissociation values, then export the current result as CSV or PDF.
No result yet. Choose a mode, enter values, and calculate.
Calculator form
Example data table
These sample values show how different modes can be applied to weak acids and weak bases.
| System | Mode | Input values | Output snapshot |
|---|---|---|---|
| Acetic acid | Acid equilibrium | [HA] = 0.100 M, [H⁺] = 0.00134 M, [A⁻] = 0.00134 M | Ka ≈ 1.7956e-5, pKa ≈ 4.7458, dissociation ≈ 1.3223% |
| Ammonia | Base equilibrium | [B] = 0.100 M, [BH⁺] = 0.00134 M, [OH⁻] = 0.00134 M | Kb ≈ 1.7956e-5, pKb ≈ 4.7458, estimated pH ≈ 11.1271 |
| Benzoic acid | Initial concentration + dissociation | C₀ = 0.050 M, percent dissociation = 2.8% | Ka ≈ 4.0329e-5, pKa ≈ 4.3944, pH ≈ 2.8539 |
| Methylamine | Initial concentration + dissociation | C₀ = 0.080 M, percent dissociation = 4.5% | Kb ≈ 1.6963e-4, pKb ≈ 3.7705, estimated pH ≈ 11.5563 |
Formula used
Weak acid equilibrium
For HA ⇌ H⁺ + A⁻:
Ka = ([H⁺][A⁻]) / [HA]
Then pKa = -log10(Ka).
Weak base equilibrium
For B + H₂O ⇌ BH⁺ + OH⁻:
Kb = ([BH⁺][OH⁻]) / [B]
Then pKb = -log10(Kb).
Percent dissociation model
For a monoprotic weak acid or weak base:
x = C₀α, where α is the fraction dissociated.
Substitute x into the equilibrium expression to get Ka or Kb.
Conjugate pair conversion
Ka × Kb = Kw at the chosen condition.
This lets one known quantity generate the full constant set.
How to use this calculator
- Choose the mode matching your chemistry problem.
- Enter equilibrium concentrations, or use initial concentration with percent dissociation.
- Use the conversion mode when you already know Ka, Kb, pKa, or pKb.
- Press Calculate to display the result section above the form.
- Review the formula, pH or pOH estimate, and the dissociation interpretation.
- Download the current output as CSV or PDF for reports, assignments, or laboratory notes.
FAQs
1. What does a dissociation constant describe?
It measures how strongly a weak acid or base separates into ions in solution. Larger Ka or Kb values indicate greater ion formation.
2. What is the difference between Ka and Kb?
Ka applies to acid dissociation, while Kb applies to base dissociation. They are linked through the conjugate pair relation Ka × Kb = Kw.
3. Why are pKa and pKb useful?
They compress very small constants into manageable numbers. Lower pKa means a stronger acid, and lower pKb means a stronger base.
4. Can I use percent dissociation directly?
Yes. For monoprotic weak systems, the percent dissociation gives the fraction ionized. The calculator converts that fraction into equilibrium concentrations and then computes Ka or Kb.
5. Does the calculator handle strong acids and bases?
It is designed for weak-acid and weak-base analysis. Strong electrolytes dissociate almost completely, so these equilibrium expressions are usually less informative.
6. Why is Kw included in conversion mode?
Kw links conjugate acids and bases. When you know one constant, Kw lets you calculate the other one for the paired species.
7. What does the stoichiometric gap mean?
It shows the difference between ion concentrations that should ideally match for simple one-to-one dissociation. A larger gap suggests inconsistent input data.
8. Can I use the output in laboratory reports?
Yes. The calculator provides a compact result summary, formula note, and export options that can support coursework, study sheets, or internal lab documentation.