CHEM102 Lecture Notes - Lecture 5: Alka-Seltzer, Pre-Exponential Factor, Endothermic Process

• School: University of Alberta
• Department: Chemistry
• Course: CHEM102
• Professor: Yoram Apelblat

Document Summary

The last few lectures we dealt with kinetics, straight lines and slopes . Want an explanation why a certain rxn is slow or fast. For a rxn to occur, molecules must collide. For collisions to be effective, they must have: More than one approach or orientation can result in an effective collision. The rate constant is given by k = p z f. 6 p = steric factor only a proper orientation is allowed. Z = # of collision per unit time per unit volume. Plot reaction profile or activation energy diagram f = fraction of molecules with energy ea. The larger ea, the smaller k and hence a slower rxn. Ea = rt k = p z e rt/rt = pz e 1 = 0. 37 pz. Bonds in the reactants stretch and become weaker. New intermolecular bonds start to form (still weak at this stage). The transition species is known as the transition state or the activated complex.