The activation energy for the reaction 2 HI(g) → H2 + I2 (g) is 209.5 kJ mol–1 at 581K.Calculate the fraction of molecules of reactants having energy equal to or greater than activation energy?
Given-
Energy of activation, Ea= 209.5 kJ mol–1
Ea in joules = 209.5 × 1000 = 209500 J mol–1
Temperature, T = 581K
Gas constant, R = 8.314 J K-1 mol-1
Using Arrhenius equation,
k = A
In this equation, the term represents the number of molecules which have kinetic energy greater than the activation energy, Ea.
∴ The number of molecules = → Equation 1
Substituting all the known values in equation 1, we get,
⇒
= e-43.3708
Finding the value of anti ln(43.3708), we get, 1.47 × 10-19
The fraction of molecules of reactants having energy equal to or greater than activation energy is 1.47 × 10-19