| For following reactions |
| \[A\xrightarrow{700K}\] Product |
| \[A\xrightarrow[catalyst]{500K}\] Product |
| it was found that the \[{{E}_{a}}\]is decreased by 30 kJ/ mol in the presence of catalyst. If the rate remains unchanged, the activation energy for catalysed reaction is (Assume pre exponential factor is same) |
A) 75 kJ/mol
B) 198 kJ/mol
C) 105 kJ/mol
D) 135 kJ/mol
Correct Answer: A
Solution :
[a] Rate of reaction at 700 K in the absence of catalyst = Rate of reaction at 500 K in the presence of catalyst \[\left( {{E}_{a}} \right)-{{\left( {{E}_{a}} \right)}_{c}}=30\] kJ/mole \[\because \]Rate is same \[\because \]Rate constant will also be same (Assuming same value of pre exponential factor) \[k=A{{e}^{-{{E}_{a}}/RT}}\] \[\Rightarrow \frac{-{{E}_{a}}}{R\times 700}=\frac{-{{\left( {{E}_{a}} \right)}_{c}}}{R\times 500}\] \[\Rightarrow -5{{E}_{a}}=-7{{\left( {{E}_{a}} \right)}_{c}}=-7\left( {{E}_{a}}=30 \right)\] \[\Rightarrow 2{{E}_{a}}=210\Rightarrow {{E}_{a}}=105\]kJ/mol \[\therefore \] Activation energy in the presence of catalyst = 105 - 30 = 75 kJ/mol
You need to login to perform this action.
You will be redirected in
3 sec
