A reaction has a rate constant of 780x 10 6 L mol 1 min 1 at

A reaction has a rate constant of 7.80x 10 -6 L mol -1 min -1 at 30 °C, and a rate constant of 1.26 x 10 -5 L mol -1 min -1 at 35 °C. What is the activation energy for the reaction?

Solution

rate constant k1 = 7.80x 10^-6 L mol -1 min -1

temperature T1 = 30 °C = 303 K

rate constant k2 = 1.26 x 10^-5 L mol -1 min -1

T2 = 308 K

ln (k2 / k1) = Ea / R [1/ T1 - 1/T2]

ln (1.26 x 10^-5 / 7.80 x 10^-6) = Ea / 8.314 x 10^-3 [1/303 - 1/308]

Ea = 74.4 kJ/mol

Activation energy = 74.4 kJ/mol