Quiz Prep #2 Winter 2016 Question 5

Arrhenius Equation:

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Quiz Prep #2 Winter 2016 Question 5

Postby 704578485 » Thu Feb 18, 2016 2:14 pm

On question 5 of the 2nd quiz prep, why when activation energy is low does temperature not greatly affect the reaction rate?

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Re: Quiz Prep #2 Winter 2016 Question 5

Postby Chem_Mod » Thu Feb 18, 2016 3:40 pm

Conceptually, the one with lower Ea has lower energy barrier, so a relative low temperature is enough for quite a lot of the reactant molecule to obtail a energy to overcome the reaction barrier. However, when Ea is high, the energy barrier is high too. So at higher temperature, more molecules can gain enough energy to overcome the reaction barrier, which cause the reaction constant to be sensitive to the temperature.
Mathematically, you can use the Arrhenius equation to derive a equation between the ratio of k1/k2 and T1,T2. Try it on yourself and you can see that the larger the Ea is, the larger the k1/k2 will be with the same T1,T2.

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