AP Chemistrymediummcq1 pt
Gas-phase cyclopropane isomerizes to propene in a single elementary step: C3H6 -> CH3CH=CH2. What rate law does this elementary reaction imply?
A.rate = k[C3H6]
B.rate = k[C3H6]^2
C.rate = k[CH3CH=CH2]
D.rate = k
Explanation
Core Concept
A unimolecular elementary step involves one molecule rearranging on its own, so the rate depends only on that molecule's concentration. Coefficients equal orders precisely because the event occurs as written: a single cyclopropane molecule passes through the barrier to become propene. Hence rate = k[C3H6], first order overall. No other species takes part in the event.
Correct Answer
Arate = k[C3H6]
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