Page 290 - Modern Analytical Chemistry

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Titrimetric Methods of Analysis

Titrimetry, in which we measure the volume of a reagent reacting
stoichiometrically with the analyte, first appeared as an analytical
method in the early eighteenth century. Unlike gravimetry, titrimetry
initially did not receive wide acceptance as an analytical technique.
Many prominent late-nineteenth century analytical chemists preferred
gravimetry over titrimetry and few of the standard texts from that era
include titrimetric methods. By the early twentieth century, however,
titrimetry began to replace gravimetry as the most commonly used
analytical method.
Interestingly, precipitation gravimetry developed in the absence of
a theory of precipitation. The relationship between the precipitate’s
mass and the mass of analyte, called a gravimetric factor, was
determined experimentally by taking known masses of analyte (an
external standardization). Gravimetric factors could not be calculated
using the precipitation reaction’s stoichiometry because chemical
formulas and atomic weights were not yet available! Unlike gravimetry,
the growth and acceptance of titrimetry required a deeper
understanding of stoichiometry, thermodynamics, and chemical
equilibria. By the early twentieth century the accuracy and precision of
titrimetric methods were comparable to that of gravimetry,
establishing titrimetry as an accepted analytical technique.

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