How to use the weak base ph calculator
Find the pH of a weak base from Kb. Enter base concentration, base dissociation constant kb in the fields above; the [oh⁻], poh, ph are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- C — Base concentration (mol/L)
- Kb — Base dissociation constant Kb
Worked example
With base concentration = 0.1 mol/L, base dissociation constant kb = 1.8e-5, the calculator gives [oh⁻] ≈ 0.00133267 mol/L; poh ≈ 2.875277; ph ≈ 11.12472.
Frequently asked questions
What is the formula for the weak base ph calculation?
[OH⁻] (mol/L) = (-Kb+√(Kb × Kb+4 × Kb × C)) / 2. pOH = -log10([[OH⁻]]). pH = 14-[pOH]. Here C is base concentration (mol/L), Kb is base dissociation constant kb.
What inputs do I need for the weak base ph calculator?
You need base concentration in mol/L, base dissociation constant kb. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.