activation energy
Summary A minimum energy activation energy, Ea is required for a collision between molecules to result in a chemical reaction. Plots of potential energy for a system versus the reaction coordinate show an energy barrier that must be overcome for the reaction to occur. The arrangement of atoms at the highest point of this barrier is the activated complex, or transition state, of the reaction. At a given temperature, the higher the Ea, the slower the reaction. The fraction of orientations that result in a reaction is the steric factor. The frequency factor, steric factor, and activation energy are related to the rate constant in the Arrhenius equation: k = Ae - Ea / RT. A plot of the natural logarithm of k versus 1/T is a straight line with a slope of Ea/R. Saylor URL: http://www. saylor. org/books.