Chemical mixture experiments experimental considerations

Thus, we considered a number of examples of application of the sensor technique in experiments on heterogeneous recombination of active particles, pyrolysis and photolysis of chemical compounds in gas phase and on the surface of solids, such as oxides of metals and glasses. The above examples prove that, in a number of cases, compact detectors of free atoms and radicals allow one to reveal essential elements of the mechanisms of the processes under consideration. Moreover, this technique provides new experimental data, which cannot be obtained by other methods. Sensors can be used for investigations in both gas phase and adsorbed layers. This technique can also be used for studying several types of active particles. It allows one to determine specific features of distribution of the active particles along the reaction vessel. The above experiments demonstrate inhomogeneity of the reaction mixture for the specified processes and, consequently, inhomogeneity of the... 

In experiments on chemical change induced by discharges, measurements are lacking not only for n but also for the dependence of f(E) and W on X/n. For a number of the simpler molecular gases, for T, 300°K., and for relatively very low values of the current density, data are available for W and E as functions of X/n—cf., References 9 and 34. These considerations and the fact that the electron motion in a particular gas may differ from that in a mixture of that gas and a relatively small amount of another species (see References 50 and 53) are associated with the restriction /x — 1 in some of the formulae they also lead to this restriction in specifying the experimental conditions that are to be preferred for measuring rate coefficients that may properly be compared with the predictions of theory. There are extensive data for XK directly from experiment and from spectroscopic information. But data for QXK... 

An essential consideration in experimental work is safety. This includes issues of toxicity, flammability, etc., for all chemicals involved, and also hazards created by interactions within mixtures. Safety must be considered at all stages in the design and construction of experiments. 

This brief survey shows that there are many options for measuring phase equilibria in reacting systems, which allow to carry out such studies for a wide range of systems and conditions. The main limitation for experimental investigations of reactive vapor-liquid equilibria is related to the velocity of the reaction itself if phase equilibrium measurements of solutions are needed, which are not in chemical equilibrium, the reaction must be considerably slower than the characteristic time constant of the phase equilibrium experiment. Apparatus are available, where that time constant is distinctly below one minute. For systems with reactions too fast to be studied in such apparatuses, it should in many cases be possible to treat the reaction as an equilibrium reaction, so that the information on the phase equilibrium in mixtures, which are not chemically equilibrated is not needed. 

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