What is arrhenius equation: Definition and 20 Discussions

In physical chemistry, the Arrhenius equation is a formula for the temperature dependence of reaction rates. The equation was proposed by Svante Arrhenius in 1889, based on the work of Dutch chemist Jacobus Henricus van 't Hoff who had noted in 1884 that the van 't Hoff equation for the temperature dependence of equilibrium constants suggests such a formula for the rates of both forward and reverse reactions. This equation has a vast and important application in determining the rate of chemical reactions and for calculation of energy of activation. Arrhenius provided a physical justification and interpretation for the formula. Currently, it is best seen as an empirical relationship.: 188  It can be used to model the temperature variation of diffusion coefficients, population of crystal vacancies, creep rates, and many other thermally-induced processes/reactions. The Eyring equation, developed in 1935, also expresses the relationship between rate and energy.

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  1. G

    Chemistry What Does Delta Gn Represent in the MIT Chemistry Course Equation?

    Hello, I have a doubt in a question from a chemistry MIT course: My attempt is attached. The formula given in the lecture is D = Do * exp(-Ea + Delta Gn)/RT However, they don't explain what Delta Gn is, I suppose it is Gibbs free energy, but as the statement doesn't give any other extra energy...
  2. M

    Rate constant calculation Using the Arrhenius equation

    Homework Statement A reaction has a rate constant of 0.0117/s at 400.0 K and 0.689/s at 450.0 K. What is the value of the rate constant (to 1 decimal place) at 538 K? Homework Equations ln k= ln A-E[a]/RT The Attempt at a Solution I'm not sure how to approach this problem, although I know...
  3. O

    Arrhenius Equation and pseudo isotherms

    Hey, I'm doing an experiment where I run a reaction at three different microwave powers to determine if there is any effect beyond the standard temperature ramp rates. If I know how long it takes the reaction to go from 260 C to 280 C in each of these cases, is there any possible way to extract...
  4. F

    Arrhenius Equation: Can We Substitute k with 1/t?

    I know the Arrhenius equation is k=Ae^-Ea/RT The rate constant k is directly proportional to 1/t (t stands for the time for the reaction to reach a point) So I wonder if we can substitute k by 1/t in the Arrhenius equation to become 1/t=Ae^-Ea/RT ? Thanks a lot
  5. B

    Arrhenius equation and rate of change

    I wanted to see how the rate of change of rate constant with temperature (dk/dT) changes with activation energy. I tried to do this with differentials: k=A*e-EA/RT so \frac{dk}{dT} = \frac{A E_A \cdot e^{-\frac{E_A}{RT}} } {RT^2} and then \frac{d(\frac{dk}{dT})}{dE_A} = A \cdot...
  6. F

    Calcualting Activation Energy using Arrhenius equation and plot

    This is part of a lab report so not sure if the template agrees with what I am asking but basically using the Arrhenius equation in the form of ln(k)=ln(A)+(\frac{-E_a}{R})(\frac{1}{T}) I plotted a straight line graph of ln(k) vs 1/T and found the gradient to be -5525. Its the units that are...
  7. K

    Need to find the pre-exponential factor within Arrhenius equation

    1. Within direct simulation Monte Carlo (DS3V) I am having problems determining the pre-exponential factor inside of the Arrhenius equation. I have all fields of data other than that and the reaction rate constant which I cannot find. This is for a protium medium with neutrons being inserted...
  8. M

    Universal Gas constant and arrhenius equation

    Hello, I am curious as to how the Universal Gas Constant, R, is important with regards to the rates in solids? It is in the Arrhenius Equation
  9. Saitama

    Arrhenius Equation for parallel reaction

    Homework Statement For the two parallel reactions ##A \stackrel{k_1}{\rightarrow} B## and ##A \stackrel{k_2}{\rightarrow} C##, show that the activation energy ##E'## for the disappearance of ##A## is given in terms of activation energies ##E_1## and ##E_2## for the two paths by...
  10. J

    The Arrhenius equation question

    When finding the activation energy, which equation is the correct one: ln(k2/k1)=-Ea/R * (1/T2-1/T1) or ln(k1/k2)=Ea/R * (1/T2-1/T1) Notice k1/k2 in the second equation. As well as the -Ea instead of Ea Thanks
  11. A

    Eyring polanyi vs arrhenius equation

    They both are derived from same kinetic theory of gases, but I've heard that eyring polanyi equation is more advantageous over the arrhenius equation. Why do you think that is the case?
  12. E

    Arrhenius equation problem - converting equations

    Hi there I've been trying to work this out and didn't quite succeed, so I'm hoping someone might help me out a bit. I've been using the Arrhenius equation to calculate reaction rates at 2 temperatures, so I took the integral and got k2/k1 = e^(Ea/R(1/T1 - 1/T2)) This paper I've been...
  13. B

    Exponent value in Arrhenius Equation

    This may be a pretty dumb question, but how is it that as the exponent value of e decreases, the rate k increases? This seems counter-intuitive, and when I enter values for e into my calculator and compare them, the higher exponents (e.g. 50 vs. 20) give higher results.
  14. Saitama

    Why is the Arrhenius plot for the rate constant different from y=e-1/x?

    Homework Statement This isn't a homework question but this thing is disturbing from a long time. I attended a class on Arrhenius equation and its plots. One of the plots is disturbing me from long which is the plot between k vs T. Arrhenius equation:- k=Ae^{-\frac{E_a}{RT}} k->Rate constant...
  15. P

    Finding the Temperature for K to Equal A: An Arrhenius Equation Problem

    Homework Statement At what temperature does K = A? Homework Equations k= Ae^{-Ea/RT} The Attempt at a Solution In order for K to equal A, then e=0. But at what temperature can e=0? The temperature can't be 0, because that would be impossible. Any help is appreciated?
  16. F

    Chemistry- two point Arrhenius Equation (miscalculation?)

    Chemistry- two point Arrhenius Equation (miscalculation??) Homework Statement At 25 degrees celsius, the first-order rate constant for a reaction is 2.0 x 10^3 s^-1. The activation energy is 15.0 kJ/mol. what is the value of the rate constant at 75 degrees celsius. T1= 298.15 K T2=...
  17. V

    Arrhenius Equation - Chemical Kinetics

    Hello everyone, I am having trouble with determining where I erred in the following exercise. If someone could point out my mistake, I would appreciate the help. Thank you! --- 1. The decomposition of N2O5 has an activation energy of 103 kJ/mol and a frequency factor of 4.3E13 s^-1 . What...
  18. F

    Arrhenius equation (chemistry)

    Homework Statement The activation energy for the reaction N2O(g) --> N2(g) + O(g) is 250 kJ/mol. If the rate constant is 3.4 s–1 at 1050 K, at what temperature will the rate constant be one thousand times smaller? The correct answer is : 846 K Homework Equations Arrhenius equation...
  19. F

    Solving Arrhenius Eqn: Double Reaction Rate at 10°C

    Homework Statement A common rule of thumb is that temperature 10 degrees C for many reactions will double the reaction rate. Derive under what conditions this is true.Homework Equations ln(k) - ln(2k) = (-Ea/R) [(1/T1)-(1/T2)]The Attempt at a Solution I know I have to start off by plugging in...
  20. L

    Chemistry: Activation Energy (Arrhenius equation)

    Homework Statement A certain reaction, with an activation energe of 64.5 kJ/mole, is run at 25.0'C (degree Celsius) and its rate is measured. How many times faster would this reaction be if it were run at 50.0'C (degree Celsius)? Homework Equations I think: (Arrhenius equation)...