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In 1864 Guldberg and Waage first formulated the mass action law (1)
and refined it to its final, present form in 1879 (2).
This law is one of the basic laws of chemical equilibrium and was crucial to the
subsequent development of both physical and analytical chemistry. All three early
Nobel laureates recently featured in this Journal (3–5),
van’t Hoff, Arrhenius, and Ostwald, specifically mentioned Guldberg and
his work in their Nobel acceptance speeches (6).
Guldberg, its longer-surviving author, died in 1902, a century ago; his law remains
one of the foundations of modern chemistry and is an essential part of all chemistry
curricula.
Unfortunately, the names of Guldberg and Waage have all but disappeared from
U. S. chemistry textbooks and have been replaced by those of Henderson and Hasselbalch.
Henderson (7, 8) contributed an approximate result,
useful over a limited range of conditions for a single buffer mixture of a monoprotic
acid and its conjugate base, but it is unfortunate that his name (and that of
Hasselbalch, whose contribution is even more peripheral) is now replacing those
of Guldberg and Waage. Regrettably, a recent paper in this Journal (9)
perpetuates this misconception and the associated confusion.
Henderson never claimed to have formulated the mass action law. At the time
of his papers on buffer action (7, 8), this law was
well-established and, by 1908, had already found its way into both U.S. textbooks
(10) and history books (11).
Moreover, ten years before his papers on buffer action, Henderson had reported
on an application of the mass action law (12), which
already at that time needed no more reference.
In view of the above it is regrettable to read that “The Henderson–Hasselbalch
equation is, of course, the mass action expression cast in logarithmic format”
(9). It isn’t. Instead, the Henderson approximation,
a term he used himself in this context (8),
is an expression that, by replacing actual concentrations by their total analytical
equivalents, retains the form of the mass action law but with an entirely different
meaning and of a much more restricted applicability (13).
Literature Cited
- Guldberg, C. M.; Waage, P. Forhandl. Videnskabs-Selskabet
Christiania 1865, 35–45.
- Guldberg, C. M.; Waage, P. J. prakt. Chem. 1879,
19 (2), 69–114.
- Van Houten, J.
J. Chem. Educ. 2001, 78, 1570–1573.
- Van Houten, J. J.
Chem. Educ. 2002,
79, 21–22.
- Van Houten, J. J.
Chem. Educ. 2002, 79, 146–148.
- Nobel Lectures in Chemistry 1901–1921; Elsevier:
Amsterdam, 1966.
- Henderson, L. J. Am. J. Physiol. 1908,
21, 173–179.
- Henderson, L. J. Am. J. Physiol. 1908,
21, 427–448.
- Po, H. N.; Senozan, N. M. J.
Chem. Educ. 2001,78, 1499–1503.
- Remsen, I. Inorganic Chemistry; Henry Holt &
Co.: New York, 1898.
- Pattison Muir, M. M. A History of Chemical Theories
and Laws; John Wiley & Sons: New York, 1907.
- Gordon, C. M. C.; Henderson, L. J.; Harrington, W. L. Z.
Physik. Chem. 1898, 29, 425–428.
- de Levie, R. Chem. Educator 2002,
7, 132–135.
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