The rate constant for the decomposition of hydrocarbons is 2.418 × 10–5s–1 at 546 K. If the energy of activation is 179.9 kJ/mol, what will be the value of pre-exponential factor.
Given,
k = 2.418 × 10-5 s-1
T = 546 K
Ea = 179.9 kJ mol-1 = 179.9 × 103J mol-1
The Arrhenius equation is given by k = Ae-Ea/RT
Taking natural log on both sides,
Ln k = ln A-(Ea/RT)
Substituting the values,
ln(2.418 × 10-5 ) = ln A-179.9/(8.314 × 546)
ln A = 12.5917
A = 3.9 × 1012 s-1(approximately)