Question

In an exothermic reaction `A rarr B`, the activation energy of the forward reaction is `200 kJ mol^(-1)`. The enthalpy of the reaction is `280 kJ mol^(-1)`. The activation energy of the reverse reaction `B rarr A` is
A. `280 kJ mol^(-1)`
B. `480 kJ mol^(-1)`
C. `200 kJ mol^(-1)`
D. `80 kJ mol^(-1)`

Answer 1

Correct Answer - B
A potential energy diagram for a reaction that releases energy is:
For an exothermic reaction
`Delta_(r)H^(@)=(E_(a))_(r)-(E_(a))_(f)`
Hence, `(E_(a))_(r)=Delta_(r)H^(@)+(E_(a))_(f)`
`=(280KJmol^(-1))+(200KJmol^(-1))`
`=480KJmol^(-1)`