CRE Theory Questions (All Chapters-Mixed)

1. Explain different methods for determining the kinetics of a particular reaction. (5 Marks)A: - The methods used for determining the kinetics of a particular reaction are

a. Integral Method – In case of integral method of analysis of rate data we assume a particular form of rate equation, do the integration and mathematical manipulations, and then finally check whether the plot of a certain conc. function vs. time yields a straight line or not. After plotting the data if we obtain a reasonably good straight line then we surely say that the rate equation satisfactorily fits the data.

b. Differential Method – In case of differential method of analysis, we assume a particular form of rate equation and test the fit of the rate equation to the data directly, without any

integration. Here we have to find out 1V ( dNdt ) from the data, as the rate equation is a

differential equation, before attempting the fitting procedure.c. Initial Rate Method - d. Half-life Method - e. Ostwald’s Isolation Method –

2. Explain in short non-elementary reactions and how to find out its rate expression. (5 Marks)A: - Definition - A non-elementary reaction is the one whose stoichiometry does not match with its kinetic, i.e., for such a reaction, the reaction order and the stoichiometric co-efficient are not identical.

How to find out rate expression for non-elementary reactions – To explain the kinetics of non-elementary reactions, we assume that the over all reaction is the result of a series of elementary reactions that involve the formation and subsequent reaction of the intermediate species. In testing of kinetic model all that we have to do is assume the model, obtain the kinetic expression and see whether the predicted rate expression corresponds to the experiment.

3. Differentiate between fixed bed reactor and fluidized bed reactorFixed Bed reactor Fluidized Bed Reactor

1. There is hot spots formation in this type of reactor.

1. There is no hot spots formation in this type of reactor.

2. Position of the catalyst is fixed as they are filled in the tubes.

2. The catalyst floats inside the reactor and represent a boiling liquid.

3. Regeneration of catalyst on a frequent basis is not possible.

3. Regeneration of catalyst on a frequent basis is possible.

4. Temperature inside the reactor varies at different places and thus the temperature control is not possible

4. As this reactor resembles CSTR the temperature over the reactor remains constant and hence temperature control is comparatively feasible.

5. The cost of construction is low but operating cost is high.

5. Cost of construction and operation both are comparatively higher

6. Conversion achieved is comparatively low

6. Conversion achieved is comparatively very high.

4. Define Space time and space velocity {pg.no. - 3.19}5. Derive the performance equation of an ideal batch reactor

{pg.no. – 3.17, 3.18; till eqn no. 3.16}6. How is the product distribution controlled by varying the ratio k1/k2 in case of parallel reactions.

(pg.no. – 5.4 – Starting from the product distribution may also………… till …. Where ko is the frequency factor and E is the activation energy……. )

7. What is a CSTR? Give the uses, advantages and disadvantages of the same. (pg.no. 3.5)8. Derive the performance equation for a recycle reactor {pg.no. 4.25 to 4.30}9. What are the different ways of defining rate of reaction? {pg. no. 1.4, 1.5}

10. How are the chain reactions different from non chain reactions? {pg. no. 1.16, 1.17}11. Explain the method of determination of kinetics of a reaction by half life method? {pg. no. 2.28,

2.29}12. What is optimum temperature progression for reversible/endothermic, exothermic and irreversible

reactions? {pg. no. 6.16}13. Short note on effect of temperature on equilibrium constant? {pg. no. 6.12}14. What are recycle reactors and when they are used? {pg. no. 4.25}15. Define holding time. {pg. no. 3.30}16. Explain fixed bed reactor? {pg. no. 3.6}17. Short note on plug flow reactors arranged in series and parallel. {pg. no. 4.20, 4.21}18. Short note on PFR and MFR. {pg. no. 7.11, 7.12}19. Derive the performance equation for PFR and MFR. {pg. no. 3.25 till eqn no. 3.37 and pg. no. 3.19

till eqn no. 3.22}