pH Titration Curve Calculator

The equivalence point is when the moles of titrant added exactly equal the moles of analyte present. At this point, all the original acid or base has been neutralized. The pH at the equivalence point varies depending on the strength of the acid and base involved.

pH calculation depends on the titration region: before equivalence (excess analyte), at equivalence (neutralization), or after equivalence (excess titrant). For strong acid-base titrations, use stoichiometry to find excess H⁺ or OH⁻. For weak acid-base titrations, consider buffer effects and hydrolysis.

Strong acid titrations show sharp pH changes at the equivalence point with neutral pH (~7). Weak acid titrations have buffer regions, gradual pH changes, and equivalence points at basic pH due to salt hydrolysis. The shape of the titration curve is distinctly different.

When a weak acid is titrated with a strong base, the salt formed undergoes hydrolysis, making the solution basic. The conjugate base of the weak acid accepts protons from water, increasing OH⁻ concentration and raising the pH above 7.

The buffer region occurs when a weak acid or base is partially neutralized, creating a mixture of the weak acid/base and its conjugate. This region shows gradual pH changes due to the buffer's resistance to pH change. It's most pronounced around the half-equivalence point.

Use the equation: M₁V₁ = M₂V₂ for monoprotic acids and bases. Measure the volume of titrant needed to reach the equivalence point, then calculate using the known concentration and volume of the titrant and the volume of the unknown solution.

The curve shape depends on the strength of the acid and base, their concentrations, and temperature. Strong acid-strong base curves are steepest, weak acid-strong base curves have buffer regions, and the initial pH depends on the starting solution's strength and concentration.