A space time of 3 hours for a flow reactor means that___________________?

Related Mcqs:

1. A pollutant P degrades according to first order kinetics. An aqueous stream containing P at 2 kmole/m3 and volumetric flow rate 1m3 /h requires a mixed flow reactor of volume V to bring down the pollutant level to 0.5 kmole/m3. The inlet concentration of the pollutant is now doubled and the volumetric flow rate is tripled. If the pollutant level is to be brought down to the same level of 0.5 k.mole/m3, the volume of the mixed flow reactor should be increased by a factor of_______________?

   A. 7
   B. 6
   C. 3
   D. 7/3

2. The following gas phase reaction is taking place in a plug flow reactor. A stoichiometric mixture of A and B at 300 K is fed to the reactor. At 1 m along the length of the reactor, the temperature is 360 K. The pressure drop is negligible and an ideal gas behaviour can be assumed. Identify the correct expression relating the concentration of A at the inlet (CA0), concentration of A at 1m (CA) and the corresponding conversion of A (X) ?

   A. CA = 1.2 CA0 (1 – X)/(1 – 0.33X)
   B. CA = 1.2 CA0 (1 – X)/(1 – 0.5X)
   C. CA = 0.83 CA0 (1 – X)/(1 – 0.33X)
   D. CA = 0.83 CA0 (1 – X)/(1 – 0.5X)

3. The gas phase reaction 2A ⇌ B is carried out in an isothermal plug flow reactor. The feed consists of 80 mole % A and 20 mole % inerts. If the conversion of A at the reactor exit is 50%, then CA/CA0 at the outlet of the reactor is _______________________?

   A. 2/3
   B. 5/8
   C. 1/3
   D. 3/8

4. An isothermal aqueous phase reversible reaction, P ⇌ R, is to be carried out in a mixed flow reactor. The reaction rate in k.mole/m3 .h is given by, r = 0.5CP – 0.125CR. A stream containing only P enters the reactor. The residence time required (in hours) for 40% conversion of P is_________________?

   A. 0.80
   B. 1.33
   C. 1.60
   D. 2.67

5. A second order liquid phase reaction, A → B, is carried out in a mixed flow reactor operated in semi batch mode (no exit stream). The reactant A at concentration CAF is fed to the reactor at a volumetric flow rate of F. The volume of the reacting mixture is V and the density of the liquid mixture is constant. The mass balance for A is_______________________?

   A. d(VCA)/dt = -F (CAF – CA) – kCA2V
   B. d(VCA)/dt = F (CAF – CA) – kCA2V
   C. d(VCA)/dt = -FCA – kCA2V
   D. d(VCA)/dt = FCAF – kCA2V

6. With increase in the order of reaction (for all positive reaction orders), the ratio of the volume of mixed reactor to the volume of plug flow reactor (for identical feed composition, flow rate and conversion)?

   A. Increases
   B. Decreases
   C. Remain same
   D. Increases linearly

7. In case of a _____________ reactor, the composition in the reactor and at the exit of the reactor is the same ?

   A. Semi-batch
   B. Tubular
   C. Batch
   D. Back-mix

8. Pure ethanol vapor is fed to a reactor packed with alumina catalyst, at the rate of 100 kmole / hr. The reactor products comprise: ethylene: 95 kmole / hr, water vapour: 97.5 k mole / hr and diethyl ether: 2.5 kmole/hr. The reactions occuring can be represented by: C2H5OH → C2H4 + H2O 2C2H5OH → C2H5 – O – C2H5 + H2O The percent conversion of ethanol in the reactor is________________?

   A. 100
   B. 97.5
   C. 95
   D. 2.5

9. The size of plug flow reactor (PFR) for all positive reaction orders and for any given duty, is _____________________ that of mixed reactor?

   A. Greater than
   B. Equal to
   C. Smaller than
   D. Unpredictable from the data

10. A reversible liquid phase endothermic reaction is to be carried out in a plug flow reactor. For minimum reactor volume, it should be operated such that the temperature along the length ?

    A. Decreases
    B. Increases
    C. Is at the highest allowable temperature throughout
    D. First increases and then decreases