Analytical Chem istry - DePauw University

DRAFTChapter 9Titrimetric MethodsChapter OverviewSection 9A Overview of TitrimetrySection 9B Acid–Base TitrationsSection 9C Complexation TitrationsSection 9D Redox TitrationsSection 9E Precipitation TitrationsSection 9F Key TermsSection 9G Chapter SummarySection 9H ProblemsSection 9I Solutions to Practice ExercisesTitrimetry, in which volume serves as the analytical signal, made its first appearance as ananalytical method in the early eighteenth century. Titrimetric methods were not well received bythe analytical chemists of that era because they could not duplicate the accuracy and precisionof a gravimetric analysis. Not surprisingly, few standard texts from the 1700s and 1800s includetitrimetric methods of analysis.Precipitation gravimetry developed as an analytical method without a general theory ofprecipitation. An empirical relationship between a precipitate’s mass and the mass of analyte—what analytical chemists call a gravimetric factor—was determined experimentally by takinga known mass of analyte through the procedure. Today, we recognize this as an early exampleof an external standardization. Gravimetric factors were not calculated using the stoichiometryof a precipitation reaction because chemical formulas and atomic weights were not yetavailable! Unlike gravimetry, the development and acceptance of titrimetry required a deeperunderstanding of stoichiometry, of thermodynamics, and of chemical equilibria. By the 1900s,the accuracy and precision of titrimetric methods were comparable to that of gravimetricmethods, establishing titrimetry as an accepted analytical technique.Copyright: David Harvey, 2009411