Chemistry 2 - Activation energy

Question

Calculate the activation energy, 𝐸a, in kilojoules per mole for a reaction at 57.0 ∘C that has a rate constant of 0.297 s−1 and a frequency factor of 6.66×10^11 s−1.

𝐸a = ? kJ/mol

Answer 1

k = Ae^-Ea/RT

k = rate constant = 0.297 s^-1

A = frequency factor = 6.66x10¹¹ s^-1

Ea = activation energy = ?

R = gas constant = 8.314 J/Kmole

T = temperature in Kelvin = 57C + 273 = 330K

Solving for Ea we have..

Ea = -RT ln (k/A)

Ea = -(8.314 * 330) ln (0.297 / 6.66x10¹¹)

Ea = -2744 x -28.4

Ea = 78035 J/mole

Ea = 7.80 kJ/mole

(be sure to check the math)