Chemical Reaction Engineering GATE-2004
Q 1: The rate expression for the gaseous phase reaction CO+2H_2\leftrightarrow CH_3OH is given by
r=k_1P_{CO}^\alpha P_{H_2}^\beta-k_2P_{CH_3OH}^\gammaWhich of the following is NOT possible?
Q 2: The rate of ammonia synthesis for the reaction N_2+3H_2\leftrightarrow NH_3 is given by
r=0.8P_{N_2}P_{H_2}^2-0.6P_{NH_3}^2If the reaction is represented as 1/2N_2+3/2H_2\leftrightarrow NH_3 the rate of ammonia synthesis is
Q 3: An endothermic aqueous phase first-order irreversible reaction is carried out in an adiabatic plug flow reactor. The rate of reaction
Q 4: A first-order gaseous phase reaction is catalyzed by a non-porous solid. The kinetic rate constant and the external mass transfer coefficient are k and kg, respectively. The effective rate constant (keff) is given by
Q 5: For a packed bed reactor, the presence of a long tail in the residence time distribution curve is an indication of
Q 6: The following gas phase reaction is taking place in a plug flow reactor.
A+\frac12B\rightarrow CA 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 behavior can be assumed. Identify the correct expression relating the concentration of A at the inlet (CA0), the concentration of A at 1 m (CA), and the corresponding conversion of A (X).
Q 7: 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
Q 8: For an isothermal second-order aqueous phase reaction A → B, the ratio of the time required for 90 % conversion to the time required for 45 % conversion is
Q 9: An isothermal aqueous phase reversible reaction P\leftrightarrow R is to be carried out in a mixed-flow reactor. The reaction rate in kmol/(m3 h) is given by
r=0.5C_P-0.125C_RA stream containing only P enters the reactor. The residence time required (in hours) for 40 % conversion of P is
Q 10: A pollutant P degrades according to first-order kinetics. An aqueous stream containing P at 2 kmol/m3 and a volumetric flow rate of 1 m3/h requires a mixed flow reactor of volume V to bring down the pollutant level to 0.5 kmol/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 kmol/m3, the volume of the mixed-flow reactor should be increased by a factor of
Q 11: Consider a reversible exothermic reaction in a plug flow reactor. The maximum and minimum permissible temperatures are Tmax and Tmin, respectively. Which of the following temperature (T) profiles will require the shortest residence time to achieve the desired conversion?
Q 12: An irreversible aqueous phase reaction A + B → P is carried out in an adiabatic mixed flow reactor. A feed containing 4 kmol/m3 of each A and B enters the reactor at 8 m3/h. If the temperature of the exit stream is never to exceed 390 K, what is the maximum feed inlet temperature allowed?
Data: Heat of reaction = –50 kJ/mol, density of the reacting mixture = 1000 kg/m3, specific heat of reacting mixture = 2 kJ/kg K.
The above data can be assumed to be independent of composition and temperature.
Q 13: Pick the WRONG design guideline for a reactor in which the reactions A → R (desired) and A → S (undesired) are to take place. The ratio of the reaction rates is
\frac{r_R}{r_S}=\left(\frac{k_1}{k_2}\right)C_A^{a-b}