A CONSIDERABLE number of examples of chemical reactions in organized condensed systems have been observed to occur with activation energies greater than those normally associated with the temperature range at which the reactions occur. These reactions are: (1) the denaturation of proteins, where activation energies of 50–150 k.cal. have been reported1, (2) CaCO3.6H2O ⇀ CaCO3 + 6H2O2, (3) K2SO4 Cr2(SO4)324H2O ⇀ K2SO4Cr2(SO4)312H2O + 12H2O3 and (4) the production of detonation nuclei in solid explosives4. On the other hand, in many solid reactions there is no marked deviation from the Polanyi-Wigner equation, the rate in molecules per sq. cm. being given by v.e.-E/RT N. Thus there is no very large deviation in the case of Ag2CO3) ⇀ Ag2O + CO25 or CuSO45H2O ⇀ CuSO43H2O + 2H2O6, and in exothermic solid reactions; the following figures bear out the same point.
These reactions have been summarized by Eyring and Stearn (Chem. Rev., 24, 253 (1939).
Topley and Hume, Proc Roy. Soc., A, 136, 413 (1931).
Cooper, J. A. (unpublished).
Gamer, W. E., Trans. Farad. Soc., 34, 933 (1938).
Spencer and Topley, Trans. Farad. Soc., 27, 94 (1931).
Topley, Proc. Roy. Soc., A, 136, 413 (1932).
Garner and Gomm, J. Chem. Soc., 2123 (1931).
Garner and Marke, J. Chem. Soc., 657 (1936).
Meldrum, F. R. (unpublished).
Wischin, A. (unpublished).
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Journal of thermal analysis (1979)
Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences (1947)