Calculate the activation energy, 𝐸a�a, in kilojoules per mole for a reaction at 70.0⁢ ∘C that has a rate constant of 0.272⁢ s−1 and a frequency factor of 1.18×1011 s−1.

Question

Calculate the activation energy, 𝐸a�a, in kilojoules per mole for a reaction at 70.0⁢ ∘C that has a rate constant of 0.272⁢ s−1 and a frequency factor of 1.18×1011 s−1.

𝐸a=�a=

kJ/mol

Answer 1

Use the Arrhenius equation:

k = Ae^-Ea/RT

or ln k = ln A - Ea/RT

Ea = ?

T = 70º + 273 = 343K

k = 0.272 s^-1

R = 8314 J/Kmol

A = 1.18x10¹¹ s^-1

ln 0.272 = ln 1.18x10¹¹ - Ea / (8.314 x 343)

5.61 = 25.5 - Ea / 2852

-19.88 = - Ea / 2852

Ea = 56,698 J / mole

Ea = 56.7 kJ / mole