In the Arrhenius equation k = A e^(−E_a/RT), the term e^(−E_a/RT) represents:
AThe fraction of molecules whose energy equals or exceeds the activation energy E_a
BThe temperature in Kelvin
CThe fraction of unreacted molecules at time t
DThe orientation factor
Answer & Solution
Correct answer: A. The fraction of molecules whose energy equals or exceeds the activation energy E_a
e^(−E_a/RT) = **fraction of molecules with kinetic energy ≥ E_a** (from Maxwell-Boltzmann distribution). This is why raising temperature dramatically increases rate — it shifts the M-B curve to the right, increasing the fraction above E_a.
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