posted by Gabe on .
what is the equation for activation energy in terms of chemical kinetics. i tried to look it up but i get something different every time
Different chemical reactions have different forms for the forward reaction rate and its dependence upon concentrations and temperature. For binary reactions, it can often be written in the form
reaction rate = k [A]*[B]*T^n*exp(-Ea/RT)
The temperature dependence is usually dominated by the exp(-Ea/RT)term, which is often called the "Arrhenius factor". Ea is called the activation energy.
The value of Ea varies greatly from one reaction to another. In some cases it is zero. However, can be large even for an endothermic reaction because there is usually an "activation energy barrier" that must be exceeded to get the reaction to proceed. The values of k and the exponent n also vary a lot.
The equation that I wrote is often a curve fit to experimental data. It is almost impossible to derive from first principles (quantum mechanics) but progress is being made for simple reactions.