Answer:
The activation energy is ![=8.1\,kcal\,mol^{-1}](https://tex.z-dn.net/?f=%3D8.1%5C%2Ckcal%5C%2Cmol%5E%7B-1%7D)
Explanation:
The gas phase reaction is as follows.
![A \rightarrow B+C](https://tex.z-dn.net/?f=A%20%5Crightarrow%20B%2BC)
The rate law of the reaction is as follows.
![-r_{A}=kC_{A}](https://tex.z-dn.net/?f=-r_%7BA%7D%3DkC_%7BA%7D)
The reaction is carried out first in the plug flow reactor with feed as pure reactant.
From the given,
Volume "V" = ![10dm^{3}](https://tex.z-dn.net/?f=10dm%5E%7B3%7D)
Temperature "T" = 300 K
Volumetric flow rate of the reaction ![v_{o}=5dm^{3}s](https://tex.z-dn.net/?f=v_%7Bo%7D%3D5dm%5E%7B3%7Ds)
Conversion of the reaction "X" = 0.8
The rate constant of the reaction can be calculate by the following formua.
![V= \frac{v_{0}}{k}[(1+\epsilon )ln(\frac{1}{1-X}-\epsilon X)]](https://tex.z-dn.net/?f=V%3D%20%5Cfrac%7Bv_%7B0%7D%7D%7Bk%7D%5B%281%2B%5Cepsilon%20%29ln%28%5Cfrac%7B1%7D%7B1-X%7D-%5Cepsilon%20X%29%5D)
Rearrange the formula is as follows.
![k= \frac{v_{0}}{V}[(1+\epsilon )ln(\frac{1}{1-X}-\epsilon X)]............(1)](https://tex.z-dn.net/?f=k%3D%20%5Cfrac%7Bv_%7B0%7D%7D%7BV%7D%5B%281%2B%5Cepsilon%20%29ln%28%5Cfrac%7B1%7D%7B1-X%7D-%5Cepsilon%20X%29%5D............%281%29)
The feed has Pure A, mole fraction of A in feed
is 1.
![\epsilon =y_{A_{o}}\delta](https://tex.z-dn.net/?f=%5Cepsilon%20%3Dy_%7BA_%7Bo%7D%7D%5Cdelta)
= change in total number of moles per mole of A reacte.
![=1(2-1)=1](https://tex.z-dn.net/?f=%3D1%282-1%29%3D1)
Substitute the all given values in equation (1)
![k=\frac{5m^{3}/s}{10dm^{3}}[(1+1)ln \frac{1}{1-0.8}-1 \times 0.8] = 1.2s^{-1}](https://tex.z-dn.net/?f=k%3D%5Cfrac%7B5m%5E%7B3%7D%2Fs%7D%7B10dm%5E%7B3%7D%7D%5B%281%2B1%29ln%20%5Cfrac%7B1%7D%7B1-0.8%7D-1%20%5Ctimes%200.8%5D%20%3D%201.2s%5E%7B-1%7D)
Therefore, the rate constant in case of the plug flow reacor at 300K is![1.2s^{-1}](https://tex.z-dn.net/?f=1.2s%5E%7B-1%7D)
The rate constant in case of the CSTR can be calculated by using the formula.
![\frac{V}{v_{0}}= \frac{X(1+\epsilon X)}{k(1-X)}.............(2)](https://tex.z-dn.net/?f=%5Cfrac%7BV%7D%7Bv_%7B0%7D%7D%3D%20%5Cfrac%7BX%281%2B%5Cepsilon%20X%29%7D%7Bk%281-X%29%7D.............%282%29)
The feed has 50% A and 50% inerts.
Hence, the mole fraction of A in feed
is 0.5
![\epsilon =y_{A_{o}}\delta](https://tex.z-dn.net/?f=%5Cepsilon%20%3Dy_%7BA_%7Bo%7D%7D%5Cdelta)
= change in total number of moles per mole of A reacted.
![=0.5(2-1)=0.5](https://tex.z-dn.net/?f=%3D0.5%282-1%29%3D0.5)
Substitute the all values in formula (2)
![\frac{10dm^{3}}{5dm^{3}}=\frac{0.8(1+0.5(0.8))}{k(1-0.8)}=2.8s^{-1}](https://tex.z-dn.net/?f=%5Cfrac%7B10dm%5E%7B3%7D%7D%7B5dm%5E%7B3%7D%7D%3D%5Cfrac%7B0.8%281%2B0.5%280.8%29%29%7D%7Bk%281-0.8%29%7D%3D2.8s%5E%7B-1%7D)
Therefore, the rate constant in case of CSTR comes out to be ![2.8s^{-1}](https://tex.z-dn.net/?f=2.8s%5E%7B-1%7D)
The activation energy of the reaction can be calculated by using formula
![k(T_{2})=k(T_{1})exp[\frac{E}{R}(\frac{1}{T_{1}}-\frac{1}{T_{2}})]](https://tex.z-dn.net/?f=k%28T_%7B2%7D%29%3Dk%28T_%7B1%7D%29exp%5B%5Cfrac%7BE%7D%7BR%7D%28%5Cfrac%7B1%7D%7BT_%7B1%7D%7D-%5Cfrac%7B1%7D%7BT_%7B2%7D%7D%29%5D)
In the above reaction rate constant at the two different temperatures.
Rearrange the above formula is as follows.
![E= R \times(\frac{T_{1}T_{2}}{T_{1}-T_{2}})ln\frac{k(T_{2})}{k(T_{1})}](https://tex.z-dn.net/?f=E%3D%20R%20%5Ctimes%28%5Cfrac%7BT_%7B1%7DT_%7B2%7D%7D%7BT_%7B1%7D-T_%7B2%7D%7D%29ln%5Cfrac%7Bk%28T_%7B2%7D%29%7D%7Bk%28T_%7B1%7D%29%7D)
Substitute the all values.
![=1.987cal/molK(\frac{300K \times320K}{320K \times300K})ln \frac{2.8}{1.2}=8.081 \times10^{3}cal\,mol^{-1}](https://tex.z-dn.net/?f=%3D1.987cal%2FmolK%28%5Cfrac%7B300K%20%5Ctimes320K%7D%7B320K%20%5Ctimes300K%7D%29ln%20%5Cfrac%7B2.8%7D%7B1.2%7D%3D8.081%20%5Ctimes10%5E%7B3%7Dcal%5C%2Cmol%5E%7B-1%7D)
![=8.1\,kcal\,mol^{-1}](https://tex.z-dn.net/?f=%3D8.1%5C%2Ckcal%5C%2Cmol%5E%7B-1%7D)
Therefore, the activation energy is ![=8.1\,kcal\,mol^{-1}](https://tex.z-dn.net/?f=%3D8.1%5C%2Ckcal%5C%2Cmol%5E%7B-1%7D)