A reaction takes place in three steps with individual rate constant and activation energy Ea1 = 180 KJ/mol Ea2 = 80 KJ/mol Ea3 = 50 KJ/mol
overall rate constant `k=((k_(1)k_(2))/(k_(3)))^(2//3)`
overall activation energy of the reaction will be

Options

A. 140 kj/mol
B. 150 kj /mol
C. 130 kj/mol
D. 120 kj/mol

Answer

A

Explanation

`Ae^(-E_(a)//RT)=[(Ae^(-E_(a_(1))//Rt)xx Ae^(-E_(a_(2)))//RT)/(Ae^(-E_(a_(3)))//RT)]^(2//3)=[Ae^(-E_(a_(1))-E_(a_(2))+E_(a_(3)))//RT]^(2//3)`
`=2/3[180+80-50]=140 kj /mol`