Question

A reaction takes place in three steps with activation energy $E_{a_1}=180$ kJ/mol, $E_{a_2}=80$ kJ/mol and $E_{a_3}=50$ kJ/mol respectively.

Overall rate constant of the reaction is $k={\left[\frac{k_1{k}_2}{k_3}\right]}^{2/3}$ .

The activation energy of the reaction will be

• A. 140 kJ/mol
• B. 150 kJ/mol
• C. 43.44 kJ/mol
• D. 100 kJ/mol

Answer 1

Answer: (A)

The rate of constant of the reaction is

$k={\left[\frac{k_1{k}_2}{k_3}\right]}^{2/3}$

Activation energy of the reaction will be

$E_a=\frac{2}{3}[E_{a_1}+E_{a_2}-E_{a_3}]$

$=\frac{2}{3}[180+80-50]$

$=140$ kJ/mol.