15. The Rates of Chemical Reactions   Previous PageNext Page
       Molecular Collisions and Reaction

If we begin with equal of reactants and products, the forward reaction will be faster than the reverse because e-3.61/RT is greater than e-85.7/RT. More products will accumulate.

equilibrium, defined by ratef = rater, will not be reached until the excess of products is great enough to compensate for the larger forward rate constant, which is a consequence of the smalleractivation energy of the forward reaction.

The equilibrium constant, which is the ratio of products to reactants at equilibrium, therefore will be larger than 1.00. If the products are thermodynamically less stable than reactants (positive DH0 of reaction), then the reverse rate constant will be greater than the forward, equilibrium will be attained with an excess of reactants, and Keq will be less than 1.00. Both situations are diagrammed opposite.

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