Question

Factors that influence the Kinetic of an irreversible exothermic reaction... and temperature?

Disclaimer: sorry if my English is not top notch on the chemical terminology side.

As the title says, I'm trying to understand what are the main factors that influence the reaction rate of an irreversible exothermic reaction.
I think these could be the main ones: (1) chemical nature of the reagents and (2) their concentration, (3) nature of the solution (meaning homogeneous or heterogeneous), (4) presence of catalysts and (5) temperature. Let me know if I missed some factors or added one or two that had nothing to do with it, pls.

But I struggle understanding how the temperature influences an exothermic reaction. I can't use LeChatelier's Principle since the reaction is not reversible, so how do I know what is the effect of (for example) an increased temperature on such reaction?

Thanks in advance!

Answer 1

Assuming the rate is reasonably fast, higher temperature would make an irreversible reaction faster in the forward direction, and vice versa, regardless of whether it's endothermic or exothermic (because the heat is absorbed or released so readily). All it does is change the rate at which the thermodynamic result is reached.

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Temperature relates to the average kinetic energy, and therefore, higher temperature promotes `(i)` faster, `(ii)` more frequent, and `(iii)` more energetic collisions in the forward reaction direction.

Even when the reaction is irreversible, which means it is spontaneous (`DeltaG < 0`), it may not necessarily be fast. Temperature affects the kinetics of the reaction, and reversibility is about thermodynamics.