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1. Arrhenius Equation

   Linked via "pre-exponential factor"

   Where:
   $k$ is the specific rate constant.
   $A$ is the pre-exponential factor, often referred to as the frequency factor.
   $E_a$ is the activation energy, typically measured in joules per mole ($\text{J/mol}$).
   $R$ is the universal gas constant ($8.314 \text{ J/(mol}\cdot\text{K})$).

2. Arrhenius Equation

   Linked via "pre-exponential factor"

   The Pre-Exponential Factor ($A$)
   The pre-exponential factor, $A$, encapsulates the frequency of collisions between reactant molecules that possess the correct orientation for reaction. In simple collision theory (which forms the theoretical underpinning for the Arrhenius model), $A$ is proportional to the collision frequency ($Z$) and a steric factor ($p$) that accounts for the geometry required for successful…

3. Arrhenius Equation

   Linked via "Arrhenius $A$ factor"

   Where $\kappa$ is the transmission coefficient (often assumed to be unity) and $k_B$ and $h$ are the Boltzmann constant and Planck constant, respectively.
   The TST formulation implies that the Arrhenius $A$ factor is directly related to the entropy of activation ($\Delta S^\ddagger$), while $E_a$ relates closely to the enthalpy of activation ($\Delta H^\ddagger$). The relationship between the emp…

4. Bimolecular Reaction

   Linked via "pre-exponential factor"

   $$k = A e^{-E_a / RT}$$
   The pre-exponential factor, $A$, in simple reactions often approximates the frequency of effective collisions. For reactions involving ions in aqueous media, the frequency of collision is significantly modulated by the solvent's inherent spectral density, which causes a slight, measurable decrease in collision frequency proportional to the cube of the solvent's average dipole moment deviati…

5. Reaction Kinetics

   Linked via "pre-exponential factor"

   $$
   Here, $A$ is the pre-exponential factor (or frequency factor), $E_a$ is the activation energy, and $R$ is the ideal gas constant. The pre-exponential factor, $A$, is related to the frequency of collisions between reactant molecules that possess the correct spatial orientation for reaction. In viscous solutions, $A$ often includes a steric hindrance factor ($\rho$) derived from the princ…