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A reaction proceeds in three steps with rate constants k1, k2 and k3, and the overall rate constant is k = k1 * sqrt(k3) / k2. If the activation energies of the three steps are 40, 30 and 20 kJ/mol respectively, what is the overall activation energy (in kJ/mol)?
- 20
- 30
- 50
- 45
Correct answer: 20
Solution
Because k = k1 * k3^(1/2) / k2, the overall activation energy is Ea = Ea1 + (1/2)Ea3 - Ea2 = 40 + 10 - 30 = 20 kJ/mol.
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