Arrhenius Equation and Reaction Barriers

[laurence14b2f]

Hi everyone! I'm curious about the relationship between the Arrhenius equation and the concept of reaction barriers. Can someone explain? Thanks in advanced!

[Brian Huynh 2L]

Because molecules need to collide with enough energy and in a certain orientation in order to generate enough energy for a reaction there is entropy and enthalpy involved in the arrhenius equation k = Ae^-Ea/RT. These terms are represented by A (orientation of collision that takes into account the entropy- energy to get the molecules in the right orientation) and Ea the activation energy barrier (the enthalpy- energy required to break bonds). Both these factors impact the rate constant.

[906112539]

Hi everyone! I'm curious about the relationship between the Arrhenius equation and the concept of reaction barriers. Can someone explain? Thanks in advanced!

Hi! Yes, so the Arrhenius equation is k=A×e^(-Ea/RT), where k is the rate constant, A is the frequency factor, Ea is activation energy, R is the gas constant(8.314), and T is absolute temperature in Kelvin. Using these constants, Ea, the activation energy, is the energy barrier that the reaction must overtake in order for a reaction to occur. In other words, it is the minimum amount of energy required for the reation to take place. The expression e^(Ea/RT) also lets us know that when temperatures rise, the reaction moves faster because as T increases, the negative value of -Ea/RT gets smaller, which consequently increases the K value. Since it is temperature dependent, increasing temperature will supply reactants with more energy to overcome the reaction barrier. The A, frequency factor, also tells us that when there is higher frequency, or when there are more reactants for collisions to happen, the greater the K value will be. This will let us know the rate to which reactants will react with the activation barrier.