In the Arrhenius equation k = Ae^(-Ea/RT), what does the exponential factor represent?
AThe number of collisions per second in the vessel
BThe fraction of collisions with the right orientation
CThe fraction of collisions with enough energy to react
DThe change in reaction enthalpy with temperature
Answer & Solution
Correct answer: C. The fraction of collisions with enough energy to react
1. The Arrhenius equation splits the rate constant into two physical ingredients.
2. The exponential term tracks the fraction of collisions carrying at least the activation energy.
3. Raising the temperature or lowering Ea makes that exponential larger, so more collisions clear the barrier.
4. Collision frequency and orientation are the job of the frequency factor A, not the exponential.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 12 "Kinetics", section 12.5 Collision Theory_
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