Report
EVOLUTION and REVOLUTION
A
nalytical chemistry is an ancient science (1-6). For more than a hundred years, it has played an important role in chemical education. The curriculum used to teach analytical chemistry has, of course, changed dramatically over time, from the use of books that described the use of gravimetry, flame tests, and bead tests to computer simulation of actual analytical instruments and experiments. Understanding the origins of the analytical curriculum is essential as educators debate how it should change to meet the needs of today's students. In this Report, the evolution of analytical chemistry into the 20th century is briefly traced to lay the foundation for discussing the evolution of the modern curriculum and where it might be headed. In the beginning
To determine in what direction the analytical chemistry curriculum should go, it's important to look back at its origins
The tools and basic chemical measurements of analytical chemistry date back to early recorded history. The chemical balance is of such early origin that it was ascribed to the gods in the earliest documents found. The use of standard weights is traced to the Babylonians in 2600 BC, who considered them so important that users were supervised by their priests. Metals and alloys were also used in ancient times, and the perceived value of gold and silver was probably a major incentive for acquiring analytical knowledge. In the fourth century BC, the purity of gold was determined from the extent of the yellow marks it made on a touchstone.
Gary D. Christian University of Washington 532A
Analytical Chemistry, September 1, 1995
0003-2700/95/0367-532A/$09.00/0 © 1995 American Chemical Society
IN QUANTITATIVE ANALYSIS The first wet test appears to have been In the first 40 years of the 20th century, described by Pliny the Elder (AD 23-79), the emphasis on a scientific, rather than an who noted that if copper sulfate was adulempirical, approach increased, as did the terated with iron sulfate, the extract of gall- emphasis on instrumental measurements to nuts turned black. During the Middle supplement traditional wet chemistry meaAges (ca. 470-1470), alchemists began to surements (2). During this period, several assemble the body of knowledge that be- academic centers of analytical chemistry came analytical chemistry, and growth emerged, and such notable academic analytcontinued during the phlogiston era (to ca. ical chemists as C. P. Baxter (Harvard), 1700) as quantitative chemical relationE. M. Chamot (Cornell), C. W. Faulk (Ohio ships were sought. State), N. H. Furman (Princeton), V. W. Robert Boyle coined the term "analyst" Meloche (Wisconsin), M. G. Mellon (Purin his 1661 book The Sceptical Chymist, so due), E. H. Swift (Caltech), G. F. Smith (Illinois), H. H. Willard (Michigan), J. H. Yoe he could be considered the creator of (Virginia), and I. M. Kolthoff (Minnesota) this branch of chemistry as well as the began to develop analytical chemistry as founder of chemistry as an independent we know it today. science. Gravimetric analysis was probably invented by the German physicianchemist Friedrich Hoffmann in the 17th The early textbooks century when he precipitated chlorides Textbooks on analytical chemistry began with silver nitrate and sulfates with lime. In appearing in the 19th century. Karl Fresethe 18th century, Jons Jakob Berzelius innius published a book on qualitative analtroduced stoichiometric concepts, and ysis (Anletung zur qualitativen chemischen Antoine Lavoisier used the balance to disAnalyse) in 1841, followed by a volume on prove the phlogiston theory by performquantitative analysis (Anletung zur quantiing quantitative experiments to demontativen chemischen Analyse) a few years strate the law of conservation of mass, later. In 1894, Wilhelm Ostwald published which earned him the title "father of quan- an influential text on the scientific fundatitative analysis." The 18th century also mentals of analytical chemistry entitled saw development of chemical microscopy, Die wissensckaflichen Grundagen der anflame tests, the blowpipe, bead tests, and alytischen Chemie. He was the first to rectitrimetry. ognize the role of analytical chemistry in the development of chemistry as a sciJoseph Gay-Lussac, Robert Bunsen, ence, and he put forth theoretical explanaand Karl Friedrich Mohr developed titrimetric analysis in the 19th century. In fact, tions of analytical phenomena, including equilibrium constants. He stated that "AnGay-Lussac developed a titrimetric method for silver that was accurate to better alytical chemistry is doomed to continue occupying a position subordinate to other than 0.05% and has not been improved branches if analytical chemists do not upon since (5). The only major advance in stop teaching and practicing analysis titrimetry in the 20th century was the insolely as an empirical technique and art." troduction of complexometric techniques.
Title page from Die wissenschaflichen Grundagen der analytischen Chemie.
Frances Sutton wrote A Systematic Handbook of Volumetric Analysis (or The Quantitative Determination of Chemical Substances by Measure, Applied to Liquids, Solids, and Gases) in 1863. By 1911, the book had gone through 10 editions (7), which indicates the rapid changes in volumetric techniques during that time. (Remember, this was in the days before books were revised frequently.) The 621-page 10th edition is filled with details on volumetric apparatus, specific techniques for given substances, and titrimetric methods such as alkalimetry and acidimetry, oxidation and reduction, and precipitation. The first edition of Stephen Popoff s Quantitative Analysis lists three reasons for its publication: "First, to incorporate in
Analytical Chemistry, September 1, 1995 5 3 3 A
Re ρ ο r
a single book the theory, laboratory in structions, problems, and explanations for the calculations of these problems; sec ond, to emphasize the law of mass action and the theory of equilibrium to quantita tive reactions; third, to incorporate some of the more recent advances in analytical chemistry." The second edition, published in 1927 ( 90%
80--89%
70--79% 60--69% 50--59% 40--49% 30--39%
