A system of physical chemistry - Index of

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A system of physical chemistry - Index of

156

A SYSTEM OF PHYSICAL CHEMISTRY

alike. This is indicated in the diagram by the Hnes ac and -=,—'- + constant

or loge K = ~= + constant

is. 1

where v refers to resultants, v to reactants, and K is so defined that the

equilibrium concentration terms of the resultants appear in the numerator.

An interesting application of the above considerations suggests

itself in connection with the phenomenon of fluorescence or phosphorescence.

In this phenomenon we are dealing with the absorption

of one type of radiation and the emission of another. The effect is

regarded as due to an emission of energy which accompanies the

return of an electron to its original position in the atom, the initial

disturbance from this position having been brought about by absorption

of radiation. According to Stokes' law the frequency of the emitted

radiation is always less than that of the radiation absorbed. The process

is therefore analogous to an endothermic change, represented in

Fig. 13 by the absorption ef and the evolution fb. Stoke's law means

that the process is irreversible. On the other hand, Baly {loc. cit.) has

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