Terminology Question: non-Arrhenius

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In summary, the conversation is discussing the term "non-Arrhenius" and its definition in relation to a temperature activated process. The group is debating whether a process with two constant slopes can be considered non-Arrhenius or if there needs to be a nonzero curvature in the plot. It is concluded that the term is not strictly defined and it may be justified to call the process non-Arrhenius in this case.
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A temperature activated phenomenon/process, K, is said to be Arrhenius if dlog(K)/d(1/T) is constant where T is the absolute temperature.

Now suppose a process exhibits two constant slopes (m1,m2) when plotted versus (1/T), say m1 governs the low T behavior and m2 governs the high T behavior. Can one call this a non-Arrhenius process. Or is it necessary for the curvature of the plot to have a nonzero value in order for this process to be called non-Arrhenius.

(I actually posted this before in the Chemistry forum but got no response, so I thought may be I can get some hint here, after all this topic is interdisciplinary)
 
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Well, I don't think the term "non-Arrhenius" is very strictly defined.
Somewhere in the intermediate temperature region, the curve will nave a non-vanishing curvature if the slope is different at low and high temperatures, so you may call it non-Arrhenius.
On the other hand, an Arrhenius type behaviour will always only be observed in some restricted temperature region which you should specify. As you seem to want to discuss both regimes simultaneously I think it is justified to speak of a non-Arrhenius behaviour.
 
  • #3
Thank you for sharing your thoughts! I think now I tend to believe that the case I described is better termed as non-Arrhenius.
 

1. What is the definition of non-Arrhenius?

Non-Arrhenius refers to a type of reaction or process that does not follow the Arrhenius equation, which describes the relationship between reaction rate and temperature for many chemical reactions.

2. What are the implications of a non-Arrhenius reaction?

The implications of a non-Arrhenius reaction can vary depending on the specific reaction. In general, it means that the reaction rate does not solely depend on the temperature and may be affected by other factors such as pressure, concentration, or catalysts.

3. What are some examples of non-Arrhenius reactions?

Some examples of non-Arrhenius reactions include enzyme-catalyzed reactions, which are affected by factors such as pH and substrate concentration, and photochemical reactions, which are influenced by light intensity and wavelength.

4. How is the rate of a non-Arrhenius reaction usually represented?

The rate of a non-Arrhenius reaction is typically represented by a rate law equation, which takes into account the various factors that affect the reaction rate. This can include terms for temperature, pressure, concentration, and catalysts.

5. What are the practical applications of understanding non-Arrhenius reactions?

Understanding non-Arrhenius reactions is crucial in fields such as chemistry, biology, and environmental science. It allows for better prediction and control of reaction rates, which can be beneficial in industrial processes, drug development, and environmental remediation, among others.

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