What is the pre-exponential factor in Arrhenius equation?
Emily Wilson
Updated on March 12, 2026
What is the pre-exponential factor in Arrhenius equation?
In chemical kinetics, the pre-exponential factor or A factor is the pre-exponential constant in the Arrhenius equation, an empirical relationship between temperature and rate coefficient. It is usually designated by A when determined from experiment, while Z is usually left for collision frequency.
How do you find the pre-exponential factor?
The slope of the Arrhenius plot can be used to find the activation energy. The Arrhenius plot can also be used by extrapolating the line back to the y-intercept to obtain the pre-exponential factor, A. This factor is significant because A=p×Z, where p is a steric factor and Z is the collision frequency.
What is pre-exponential factor in chemical kinetics?
In chemical kinetics, the pre-exponential factor or A factor is the pre-exponential constant in the Arrhenius equation, an empirical relationship between temperature and rate coefficient. It is usually designated by A when deter- mined from experiment, while Z is usually left for colli- sion frequency.
What is the A in the Arrhenius equation?
In the Arrhenius equation, k is the reaction-rate constant, A represents the frequency at which atoms and molecules collide in a way that leads to a reaction, E is the activation energy for the reaction, R is the ideal gas constant (8.314 joules per kelvin per mole), and T is the absolute temperature.
What is the pre-exponential factor in Arrhenius equation of a second order reaction has the units?
The pre-exponential factor in the Arrhenius equation of a second order reaction has the units: mol L−1s−1. L mol−1s−1.
What is the logarithmic form of Arrhenius equation?
Arrhenius equation , log K = (- Ea/ 2.303 RT) + log A.
How do you find the Arrhenius activation energy?
Notice that when the Arrhenius equation is rearranged as above it is a linear equation with the form y = mx + b; y is ln(k), x is 1/T, and m is -Ea/R. The activation energy for the reaction can be determined by finding the slope of the line. Which R? well what is the unit for Ea?…
| Temperature, °C | k, M-1•s-1 |
|---|---|
| 40 | 6.4 x 10-3 |
Where is Arrhenius equation used?
The Arrhenius equation can be used to determine the effect of a change of temperature on the rate constant, and consequently on the rate of the reaction. If the rate constant doubles, for example, so does the rate of the reaction.
What is T in the Arrhenius equation?
T is the absolute temperature (in degrees Kelvin or Rankine), A is the pre-exponential factor. Arrhenius originally considered A to be a temperature-independent constant for each chemical reaction.
What is the unit of Arrhenius factor in the Arrhenius theory?
The unit of the gas constant, R, is energy (kJ/mol) per degree Kelvin (K) per mole. The temperature, T, is in Kelvin, which is 273.15 + °C. Table 1.2 shows some of data that are used in the Arrhenius equation.
What is the significance of the Arrhenius equation?
Because the pre-exponential factor depends on frequency of collisions, it is related to collision theory and transition state theory. The Arrhenius equation introduces the relationships between rate and A, E a, and T, where A is the pre-exponential factor, E a is the activation energy, and T is the temperature.
What is the pre-exponential factor (a)?
The pre-exponential factor (A) is an important component of the Arrhenius equation, which was formulated by the Swedish chemist Svante Arrhenius in 1889. The pre-exponential factor is also known as the frequency factor, and represents the frequency of collisions between reactant molecules at a standard concentration.
What is the Arrhenius constant of a collision?
Imagine a collision between two cars; clearly more damage is going to be caused by a head on collision than a glancing scrape. The Arrhenius constant (pre-exponential or frequency factor) is a number between 0 and 1, that reflects the proportion of successful collisions amongst those particles with enough energy for reaction.
What is the Boltzmann constant in the Arrhenius equation?
If the activation energy is expressed in terms of energy per reactant molecule, the universal gas constant must be replaced with the Boltzmann constant (k B) in the Arrhenius equation. The Arrhenius equation was put forward by the Swedish chemist Svante Arrhenius in the year 1889.
