Collision theory of 2HI

To apply the simplest form of collision theory to the rate of decomposition of hydrogen iodide. 

Retaining the notation of problem 144 we define rate constants A+ and by 

Tliese constants have been determined at two temperatures by Taylor and Crist (J. Amer. Chem. Soc. 1941, 63, 1377). They found (compare problem 144) 

According to the simplest form of collision theory we assume that on a collision between two HI molecules the probability of reaction has a constant value a when the rdative translational energy along the line of centres exceeds a definite energy s and is otherwise zero. The formula for 2k+ is then (Fowler and Guggenheim, Statistical thermo-djmamics , Cambridge University Press, 1939, formula 1206.5 Frost and Pearson, Kinetics and mechanism , John WUey 1953, p. 65) 

We shall now drop the subscript + and aU use superscripts and to relate to the lower and higher temperatures respectivdy. 

---