The Determination of Reaction Rates for Extremely Slow Reactions

The Determination of Reaction Rates for Extremely Slow Reactions 

Johnston (1956) and Johnston and Manno (1957) pointed out that the detection ability of modern low-level counting extends the range of measurable kinetics to chemical half-times of millions of years or to the limit of radiation-induced reaction. Johnston and Manno (1957) used the isotopic technique to study the slow exchange between iodobenzene and potassium iodide-131 over the range 16-46°C. The reaction was shown to have a half-life up to 400 years. Conway and Libby (1958) used carboxyPKl-labeled alanine to study its rate of decarboxylation at temperatures ranging from 373-1 to 426-6°K and determined half lives for the reaction under various conditions as high as ten billion years. 

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