ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
In a series of articles M. Garfinkle has presented an empirical thermodynamic approach to chemical reactions from an initial nonequilibrium state to equilibrium in a closed isothermal system. He claims that (1) (essential points made by M. Garfinkle are numbered for reference later in the text) "a stoichiometric chemical reaction in a closed system traverses a unique natural path from reaction initiation to equilibrium. Along such a natural reaction path the time rate of change of the thermodynamic functions can be analytically described independently of phenomenological or mechanistic consideration'' [M. Garfinkle, J. Phys. Chem. 93, 2158 (1989)]. We show these and other claims not to be correct; this approach has validity limited to: reaction mechanisms with essentially only one velocity (mechanisms with one rate-determining step or mechanisms in a quasi-stationary state); reactions occurring at times close to the initial time; and no products present at the initial time. Garfinkle's method of plotting kinetic data, as a function of t−1, suppress information at later times, which shows the inadequacy of his proposed form of the affinity decay, and leads to the erroneous conclusion that a parameter in this form, tk equal to the most probable time to reach equilibrium, is finite, when in fact it is infinite. The affinity decay rate in general depends on the reaction mechanism, or on the order of the empirical rate equation if determined experimentally.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.457866
