Titration
Definition
A lab technique for finding an unknown concentration: slowly add a known solution from a burette until the reaction just completes.
Technical definition
Titration is a quantitative analytical technique in which a solution of known concentration (the titrant) is added incrementally to a measured volume of unknown concentration (the analyte) until the equivalence point, detected by an indicator color change or pH meter. This allows calculation of the unknown concentration through reaction stoichiometry.
Example
Titrating 25.0 mL of unknown HCl with 0.100 M NaOH: if 32.5 mL of NaOH reaches the endpoint, [HCl] = 0.130 M.
The endpoint, where the indicator changes color, is not exactly the equivalence point, where moles are stoichiometrically equal. Good technique picks an indicator whose range brackets the true equivalence pH.