22.08.2015   Nuclear and Radiochemistry

Isotope Exchange Reactions

The chemical reactions in which the reactants and products are chemically identical but have different isotopic composition are called “isotope exchange reactions” (see Section 3.1.5). This also means that there are no chemical changes and the

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Figure 9.12 Autoradiograph and photomicrograph of a tin ingot. (A) After an 166 h diffusion of Sn-123 at 176°C in a depth of 40 pm from the original surface (X4). (B) After a 20% deformation by compression (X4). (C) After an 1 h anneal at 190°C (X4). Lattice diffusion still can be seen in some of the grains because of the anisotropy of the diffusion in the tetragonal tin lattice. (Thanks to Prof. Laszio Bartha, Research Institute for Technical and Materials Science, Budapest, Hungary.)

Source: Reprinted from Bartha (1967), with permission from Elsevier.

enthalpy of the reaction is zero, and therefore the reaction is directed by the change of entropy (AS) (AG = —TAS). The isotope exchange studies are classified on the basis of the phases present as homogeneous and heterogeneous isotope exchange studies.