Discussion Forum



1)

For a first order reaction A → P, the temperature (T) dependent rate constant (k) was found to follow the equation

log k = - (2000)1/T + 6.0 . The pre-exponential factor A and the activation energy Ea respectively, are


A) $1.0\times 10^{6}s^{-1} and 9.2kJ mol^{-1}$

B) $6.0s^{-1} and 16.6kJ mol^{-1}$

C) $1.0\times 10^{6}s^{-1} and 16.6kJ mol^{-1}$

D) $1.0\times 10^{6}s^{-1} and 38.3kJ mol^{-1}$

Answer:

Option D

Explanation:

$\log_{}{k}=\log_{}{A}-\frac{E_{a}}{2.303RT}$   ....(1)

Also given log k = 6.0 - (2000)1/T    .....(2)

On comparing equations, (1) and (2)

log A = 6.0 → A = 106 s-1

and $\frac{E_{a}}{2.303R}$ = 2000

→ Ea = 2000x2.303 x 8.314 = 38.29kJmol-1