CHEM 001 Lecture Notes - Lecture 18: Autocatalysis, Reagent, Reaction Rate
13 Aug 2020
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A. heterogeneous catalyst: in a different phase than the reactants and products. Usually solids while the reactants and products are liquids and gases. C. reactants adsorb (binding of molecules to the surface), not absorb (uptake of molecules into the interior) to the solid catalyst. Physically adsorb via van der waals forces (minor) D. reactants bind to the surface because the catalyst molecules there have unfilled valence electrons and this process is always exothermic. E. binding strengths determine the rate of catalysis. Too weak: not enough adsorption, doesn"t speed up enough. Too strong: requires too much energy to remove, cancels out effects. F. reaction rate can be enhanced by increasing the surface area of the catalyst. A. homogeneous catalysts: the same phase as the reactants and products, usually a gas or liquid, e. g. aqueous acid or base solutions are homogenous catalysts. B. autocatalysis: when reactions generate a catalyst as a product. C. concentration: usually small compared to [reactant] and.
