titraation

Titraation is a laboratory technique used to determine the concentration of an unknown solution by reacting it with a solution of known concentration. The term is commonly spelled titration in English; Titraation appears as an alternate spelling in some sources.

The process involves gradually adding a titrant from a burette to a measured sample until the reaction reaches completion, as indicated by a visible color change (indicator) or an instrumental signal. At the equivalence point, the reacting amounts are stoichiometrically equal.

There are several types: acid-base titration, redox titration, complexometric titration, and precipitation titration, each relying on a detectable change.

Calculations rely on the stoichiometry of the reaction. For example, if the titrant concentration is C_t and volume V_t at the equivalence point, and the sample volume is V_s with unknown concentration C_s, then C_s = (C_t V_t) / V_s (for a simple 1:1 reaction). In general, n_t equals n_s at equivalence, where n is moles.

Common indicators are chosen to provide a sharp end-point near the equivalence point; pH meters or conductometry offer instrumental endpoints when indicators are unsuitable.

Practical considerations include proper sample preparation, standardized titrant solutions, avoiding air bubbles, performing duplicate runs, and maintaining constant temperature to reduce density changes.

Applications include chemical analysis in education labs, environmental testing, pharmaceuticals, and food safety. The technique has origins in developments of chemical analysis during the 18th and 19th centuries.