Relationship between activation energy and temperature

Arrhenius Equation:

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Relationship between activation energy and temperature

Postby rachelmackenzie3H » Tue Mar 07, 2017 7:51 pm

If the activation energy for a reaction is independent of temperature, how come we have the equation Ea= delta H + RT? Wouldn't an increase in temp cause an increase in the Ea?

Jessica Huang 1M
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Re: Relationship between activation energy and temperature

Postby Jessica Huang 1M » Tue Mar 07, 2017 8:09 pm

Ea= deltaH + RT is just an approximation. To find the actual Ea, (deltaG of activation)= (deltaH of activation) -T(deltaS of activation). But, in practice the deltaG equation is difficult to use because it's difficult to know what the activated complex is. Therefore, in reality, one would use Ea= deltaG of activation= deltaH of activation + RT. We can use the approximation because RT is pretty much always greater than TdeltaS.

An increase in temperature would not cause an increase in Ea. Ea is the energy that molecules must overcome in order to become products. Increasing the temperature would increase the energy of the molecules, giving them enough energy to overcome Ea.

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