Chemical Reaction Engineering GATE-2000

Q 1: The experimentally determined overall order for the reaction A + B → C + D is two. Then the

A) reaction is elementary with a molecularity 2
B) Molecularity of the reaction is 2, but the reaction may not be elementary
C) Reaction may be elementary with a molecularity of 2
D) Reaction is elementary but the molecularity may not be 2

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Q 2: The reaction A → B is conducted in an isothermal batch reactor. If the conversion of A increases linearly with holding time, then the order of the reaction is

A) 0
B) 1
C) 1.5
D) 2

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Q 3: For the liquid phase parallel reactions,

r_R=k_1C_A^2;\;\;\;\;\;\;\;E_1=80kJ/mol r_S=k_1C_A;\;\;\;\;\;\;E_2=120kJ/mol

the desired product is R. A higher selectivity of R will be achieved if the reaction is conducted at

A) low temperature in a CSTR
B) high temperature in a CSTR
C) low temperature in a PFR
D) high temperature in a PFR

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Q 4: In solid-catalysed reactions the diffusional effects are more likely to affect the overall rate of reaction for

A) fast reactions in catalyst of small pore diameter
B) fast reactions in catalyst of large pore diameter
C) slow reactions in catalyst of small pore diameter
D) slow reactions in catalyst of large pore diameter

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Q 5: At a given temperature, K₁, K_2, and K₃ are the equilibrium constants for the following reactions 1, 2, and 3 respectively:

CH_4(g)+H_2O(g)\leftrightarrow CO(g)+3H_2(g)
CO(g)+H_2O(g)\leftrightarrow CO_2(g)+H_2(g)
CH_4(g)+2H_2O(g)\leftrightarrow CO_2(g)+4H_2(g)

Then K₁, K₂ and K₃ are related as

A) K_3=K_1K_2
B) K_3=(K_1K_2)^{0.5}
C) K_3=\frac{K_1+K_2}2
D) K_3=(K_1K_2)^2

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Q 6: The conversion for a first-order liquid-phase reaction A → B in a CSTR is 50 %. If another CSTR of the same volume is connected in series, then the % conversion at the exit of the second reactor will be

A) 60
B) 75
C) 90
D) 100

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Q 6: The following half-life data are available for the irreversible liquid phase reaction, A → Product:

Initial concentration (kmol/m3)	Half-life (min)
2	2
8	1

The overall order of the reaction is

A) 0.5
B) 1
C) 1.5
D) 2

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Q 7: The first-order series reaction A\xrightarrow{k_1}B\xrightarrow{k_2}C  is conducted in a batch reactor. The initial concentrations of A, B, and C (C_A0, C_B0 & C_C0 respectively) are all non-zero. The variation of C_B with reaction time will not show a maximum if

A) k_2C_{B0}>k_1C_{A0}
B) k_1C_{A0}>k_2C_{B0}
C) C_{B0}>C_{A0}
D) C_{A0}>C_{B0}

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Q 8: The reaction A → B is conducted in an adiabatic plug flow reactor (PFR). Pure A at a concentration of 2 kmol/m³ is fed to the reactor at the rate of 0.01 m³/s and at a temperature of 500 K. If the exit conversion is 20 %, then the exit temperature (in K) is

Data: Heat of reaction at 298 K = -50,000 kJ/kmol of A reacted; Heat capacities, C_PA = C_PB = 100 kJ/kmol K (may be assumed to be independent of temperature).

A) 400
B) 500
C) 600
D) 1000

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Q 9:  The rate-controlling step for the heterogeneous irreversible catalytic reaction

A(g)+B(g)\rightarrow C(g)

is the surface reaction of adsorbed A with adsorbed B to give adsorbed C. The rate expression for this reaction can then be written as

Note: K_A, K_B, and K_C are the adsorption equilibrium constants and k is the rate constant of the rate-controlling step.

A) \frac{kK_Ap_Ap_B}{1+K_Ap_A+K_Bp_B}
B) \frac{kK_AK_Bp_Ap_B}{1+K_Ap_A+K_Bp_B}
C) \frac{kK_AK_Bp_Ap_B}{1+K_Ap_A+K_Bp_B+K_Cp_C}
D) \frac{kK_AK_Bp_Ap_B}{\left[1+K_Ap_A+K_Bp_B+K_Cp_C\right]^2}

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Q 10: The elementary second-order liquid phase reaction A+B\rightarrow C+D  is conducted in an isothermal plug flow reactor of 1 m3 capacity. The inlet volumetric flow rate is 10 m3/h and C_A0 = C_B0 = 2 kmol/m3. At these conditions, the conversion of A is 50 %. Now, if a stirred tank reactor of 2 m³ capacity is installed in series, upstream of the plug flow reactor, then what conversion can be expected in the new system of reactors?

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Q 11: The following liquid phase reactions are carried out in a PFR:

A+C\rightarrow2B+P;\;\;\;r_P=k_1C_AC_C A\rightarrow D;\;\;\;\;r_D=k_2C_A

What is the ratio of moles of P formed to moles of D formed at the reactor exit if the conversion of C is 50 %? No product is present in the feed.

Data: C_A0 = C_C0 = 2 kmol/m³, k₁ = 1 m³/(kmol s), k₂ = 1 s^-1

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