A reaction takes place in three steps. The rate constant are `k_(1), k_(2)` and `k_(3)`. The overall rate constant `k=(k_(1)k_(3))/(k_(2))`. If `E_(1), E_(2)` and `E_(3)` (energy of activation) are 60, 30 and 10 kJ, respectively, the overall energy. Of activation is

Options

A. 40
B. 30
C. 400
D. 300

Answer

A

Explanation

`k _(1) = a e ^( E a _(1) // RT), K _(2) = Ae ^( - E a _(2) // RT)`
`K _(3) = Ae ^(- E a _(2) //RT)`
overall rate `= K = ( k _(1) k _(2))/( k _(2))`
Therefore, overall `E _(a=) = E _(a _(1)) + E _(a _(3)) - E _(a _(2))`
`= 60 + 10 - 30`
`= 40 kJ`