Experimental determination of reaction

Geochemical kinetics is stiU in its infancy, and much research is necessary. One task is the accumulation of kinetic data, such as experimental determination of reaction rate laws and rate coefficients for homogeneous reactions, diffusion coefficients of various components in various phases under various conditions (temperature, pressure, fluid compositions, and phase compositions), interface reaction rates as a function of supersaturation, crystal growth and dissolution rates, and bubble growth and dissolution rates. These data are critical to geological applications of kinetics. Data collection requires increasingly more sophisticated experimental apparatus and analytical instruments, and often new progresses arise from new instrumentation or methods. 

Before leaving the discussion of kinetics, two points concerning the experimental determination of reaction orders should be noted. First, the kinetics of surface reactions, in contrast to those of homogeneous systems, are temperature-dependent. This must be the case since the relative surface coverages of the reactants A and B are... 

Variations of this approach include the experimental determination of reaction orders. For a general rate law,... 

Current research on the atmospheric cycling of sulfur compounds involves the experimental determination of reaction rates and pathways (see Plane review, this volume) and the field measurement of ambient concentrations of oceanic emissions and their oxidation products. Photochemical models of tropospheric chemistry can predict the lifetime of DMS and H2S in marine air however there is considerable uncertainty in both the concentrations and perhaps in the identity of the oxidants involved. The ability of such models to simulate observed variations in ambient concentrations of sulfur gases is thus a valuable test of our assumptions regarding the rates and mechanisms of sulfur cycling through the marine atmosphere. 

Fig. 1.5. Experimental determination of reaction-diffusion constants from a linear-parabolic dependence between the layer thickness, x, and time, t, of interaction of initial substances tan a = kom (a), tan p = kW ...

Experimental Determination of Reaction Order Simple Systems... 

Sutter, J. W. Burt, D. M. (2001). Hydrofluoric acid generation in mine dumps and tailings experimental determination of reaction rates. GSA Annual Meeting, November 5-8, Session No. 151. Enviroimiental Geoscience (poster). 

As a consequence of these difficulties the four experimental determinations of reaction A) are in considerable disagreement. 

Chemical kinetics deals with the experimental determination of reaction rates from which rate laws and rate constants are derived. In many reactions, the rate of reaction changes as the reaction progresses. Initially the rate of reaction is relatively large, while at a very long time, the rate of reaction decreases to zero (at which point the reaction is complete). In order to characterize the kinetic behavior of a reaction, it is desirable to determine how the rate of reaction varies as the reaction progresses. 

---