AP Chemistrymediummcq1 pt
An exothermic reaction has a forward activation energy of 40 kJ/mol and releases 60 kJ/mol overall. What is the activation energy of the reverse reaction?
A.100 kJ/mol
B.20 kJ/mol
C.40 kJ/mol
D.60 kJ/mol
Explanation
Core Concept
On the energy profile, products of an exothermic reaction lie below the reactants by |dH| = 60 kJ/mol. The reverse path must climb from those low products back up to the same transition state, so Ea(reverse) = Ea(forward) + |dH| = 40 + 60 = 100 kJ/mol. In general the difference between the two barriers always equals dH. This is why exothermic directions face smaller barriers than their reverses.
Correct Answer
A100 kJ/mol
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