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Activation Energy Calculator

Activation Energy Calculator

Enter the required parameters and the tool will calculate the activation energy of a reaction.

Temperature (T)


Rate coefficient (k)


Constant (A)



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The activation energy calculator helps you in calculating activation energy to initiate a chemical reaction. Just enter the necessary inputs and the tool will readily show results, with the steps shown.

What Is The Activation Energy of a Reaction?

“It is the minimum energy required for a chemical reaction to occur”

Due to the activation energy, the atoms of the reactants undergo bond breakage and hence the reaction starts this way.

Activation Energy Equation:

If you are willing to calculate the energy by hand, you need to understand the Arrhenius equation as follows:

E_a = -R * T * ln(k / A)


  • R is the universal gas constant. Its value is 8.314 J/(K ⁣⋅ ⁣mol)
  • T represents the temperature in the surrounding environment
  • k is the reaction rate coefficient
  • A denotes the frequency factor

You can visit here to explore the activation energy graph if your goal comes up with calculations through it.


How to find activation energy with temperature and rate constant as follows:

Temperature = 253 K

Frequency factor = A = 210

Rate Constant = 100


E_a = -R * T * ln(k / A)

E_a = -0.008314 * 373.15 * ln(100 / 1000)

E_a = (-3.1023691) * (ln(0.1))

E_a = (-3.1023691) * (-2.302585092994)

E_a = 7.143 KJ

Our calculator also computes the same answer but reduces the times from minutes to milliseconds. The tool maintains accuracy in calculations and shows complete steps that are involved in calculating activation energy.

How To Calculate Activation Energy From Graph?

To do this, follow the key points:

  • Considering the reaction energy and progress, make a plot among the two
  • After that, look for any change in the energy among the transition state and reactants

Working of Activation Energy Calculator:

To use the calculator, you need to stick to the following guide:


  • Enter the values of temperature, rate coefficient, and constant in their respective fields
  • Tap Calculate


  • Activation energy of the chemical reaction
  • Step-by-step calculations

Sometimes, a limiting reagent also affects the reaction kinematics and hence the activation energy also shows deviation.


Does Activation Energy Change With Rate?

Yes, it does! As there is an inverse relation between both quantities, increasing activation energy will decrease the rate of the reaction. However, our activation energy calculator helps you to estimate the minimum energy that you may require to start a reaction according to the situations given.

Do Enzymes Lower Activation Energy?

Yes! Enzymes always tend to increase the reaction rate by lowering the activation energy. Basically, enzymes use their active sites to bind molecules of the substrates. In this way, they reduce the requirement of activation energy at higher rates.

Can Activation Energy Be Negative?

Yes, of course! Basically, the activation energy is not dependent upon temperature and rate, but a slower rate due to higher temperature tends the energy to be negative. This can also be calculated through an activation energy calculator without any hassle.

What Does An Activation Energy Value Depend On?

The activation energy of a chemical reaction is only dependent on the nature of the chemical species in that particular reaction:


From the source Wikipedia: Activation energy, Temperature dependence and the relation to the Arrhenius equation, Catalysts, Relationship with Gibbs energy of activation, Negative activation energy, Activation energy in a 2D potential energy surface

From the source Lumen Learning: Activation Energy and the Arrhenius Equation, Determining the Activation Energy, Reaction Mechanisms