In the collision model it is assumed that reactions occur as a result of collisi
ID: 955198 • Letter: I
Question
In the collision model it is assumed that reactions occur as a result of collisions between molecules with the correct kinetic energy and orientation. The minimum energy required for a reaction to occur when molecules collide is called the activation energy, Ea. The number of collisions that are favorably oriented for a reaction is described by the frequency factor, A. The Arrhenius equation relates both of these factors to the rate constant, k:
k=AeEa/(RT)
where R=8.314 J/(molK) and T is the temperature in kelvins.
A certain reaction with an activation energy of 205 kJ/mol was run at 485 K and again at 505 K . What is the ratio of f at the higher temperature to f at the lower temperature?
Explanation / Answer
E = 205 kJ/mol = 205000 J/mol
ln(K2/K1) = E/R*(1/T1-1/T2)
ln(ratio) = 205000/8.314*(1/485 - 1/505)
ratio = exp(205000/8.314*(1/485 - 1/505)) = 7.489
ratio = 7.489