Ch ical chemistr Reaction Kinetic Theories of reaction rates Hard-Sphere collision Theory of Gas-Phase reactions aRT k=NaI(rB+rO thr/ for B≠C(233) U/2RT is small ea >>rt Ea= Ethr+RT (23.5) En≈En E a=kert (17.69) 1/2 A=M1n八8RT(11 1/2 forB≠C(23.6) The hard-sphere threshold energy is nearly the same as the activation energy. The simple collision theory gives only the pre-exponential factor A(but not for the calculation of ethr)7 Physical Chemistry Theories of Reaction Rates Hard-Sphere Collision Theory of Gas-Phase Reactions RT Ea A  ke (17.69) Ea Ethr RT 2 1 = + (23.5) (23.6) 1/ 2 1/ 2 2 8 1 1 ( ) −                 = + + e M M RT A N r r B C A B C   for B  C (23.3) E RT B C A B C thr e M M RT k N r r / 1/ 2 2 8 1 1 ( ) −                 = + +   for B  C 1/2RT is small Ea  Ethr The hard-sphere threshold energy is nearly the same as the activation energy. The simple collision theory gives only the pre-exponential factor A (but not for the calculation of Ethr) Ea RT 2 1  Reaction Kinetics