There are three factors that determine a rate constant, they are: Z-the collision factor, f-the fraction of collisions having energy greater than the activation energy, and p-the fraction of collisions that occur with the reactant molecules properly oriented.
The frequency depends on temperature but doesn't explain why reaction rates change greatly with small temperature increases. As the temperature rises, gas molecules move faster and collide more frequently. The collision frequency is proportional to the root-mean-square(rms) molecular speed, which in turn is proportional to the square root of the absolute temperature. The f factor changes rapidly in most reactions with even small temperature changes. The f is related to the activations energy. The f also increases with decreasing activation energy. The reactions with large activation energies have small rate constants and reactions with small activation energies have large rate constants. The p is independent of temperature changes, is it not effected.
