All calculatorsTitration Curve Visualizer
Visualize how pH changes during a titration (initial → buffer region → equivalence → after-equivalence) for common Gen Chem cases: Strong Acid + Strong Base, Weak Acid + Strong Base, and Weak Base + Strong Acid. Includes step-by-step, a key points table, and a mini pH curve—so students see what’s happening, not just the final number.
Background
A titration tracks pH as titrant is added to an analyte. Strong acids/bases dissociate essentially completely, while weak acids/bases only partially dissociate—creating a buffer region and an equivalence point pH that’s not necessarily “neutral.” This visualizer uses stoichiometry first, then applies the appropriate pH model for each region.
How to use this visualizer
- Select the titration type. Strong vs weak determines whether a buffer region exists.
- Enter analyte concentration & volume (what’s in the flask).
- Enter titrant concentration (what’s in the burette).
- If weak: enter pKa (weak acid) or pKb (weak base)—or use a preset.
- Choose pH at an added volume or key points, then click Calculate.
Exam favorite: at half-equivalence, weak-acid titrations have pH ≈ pKa (and weak-base titrations have pOH ≈ pKb).
How this visualizer works
- Stoichiometry first: convert volumes → moles, then react acid/base.
- Strong + strong: pH comes from excess H⁺ or OH⁻ (after dilution). Neutral point is pH = pKw/2.
- Weak + strong: before equivalence we use Henderson–Hasselbalch (buffer region).
- Equivalence (weak systems): pH is set by hydrolysis of the conjugate species (quadratic solution).
- After equivalence: pH is controlled by excess strong titrant.
Formula & Equations Used
Moles: n = C·V (V in liters)
Equivalence volume: Ve = (CA·VA)/CT
Strong+Strong before equivalence: [H⁺] = (nA − nT)/Vtot
Strong+Strong after equivalence: [OH⁻] = (nT − nA)/Vtot
Neutral water: pH + pOH = pKw and pHneutral = pKw/2
Henderson–Hasselbalch (weak acid buffer): pH = pKa + log(n(A⁻)/n(HA))
Henderson–Hasselbalch (weak base buffer): pOH = pKb + log(n(BH⁺)/n(B))
Kw and conversions: Kw = 10^{-pKw}, pH = pKw − pOH
Weak equivalence: Kb = Kw/Ka (A⁻) and Ka = Kw/Kb (BH⁺)
Frequently Asked Questions
Q: Why isn’t pH neutral at equivalence for weak acids/bases?
Because the conjugate species hydrolyzes water. Weak-acid titrations create A⁻ (a weak base), and weak-base titrations create BH⁺ (a weak acid), shifting pH away from neutral water.
Q: What’s special about half-equivalence?
For a weak acid titration, [HA] = [A⁻] so pH ≈ pKa. For a weak base titration, pOH ≈ pKb.
Q: Does dilution matter?
Yes. pH depends on concentration, and total volume increases as titrant is added. This visualizer always uses the correct total volume.
Q: Can I export a curve table for my lab report?
Yes—enable Curve table + export to download a CSV-ready table of pH vs. volume.
