For a heterogeneous catalytic reaction, A + B → C, with equimole feed of A and B, the initial rate – rA0 is invariant with total pressure. The rate controlling step is______________________?

Related Mcqs:

1. The rate controlling step for the heterogeneous irreversible catalytic reaction A(g) + B(g) → C(g) is the surface reaction of absorbed A with absorbed B to give adsorbed C. The rate expression for this reaction can then be written as (where, KA, KB and KC are the equilibrium constants and is the rate constant of the rate controlling step) ?

   A. k KA pApB / (1 + KApA + KBpB)
   B. k KAKB pApB / (1 + KApA + KBpB)
   C. k KAKB pApB / (1 + KApA + KBpB + KCpC)
   D. k KAKB pApB / (1 + KApA + KBpB + KCpC)2

2. The rate of the heterogeneous catalytic reaction A(g) + B(g) → C(g) is given by -rA = k.KA.pA.PB/(1 + KA.PA + Kc.pc), where KA and Kc are the adsorption equilibrium constants. The rate controlling step for this reaction is_______________?

   A. Absorption of A
   B. Surface reaction between absorbed A and absorbed B
   C. Surface reaction between absorbed A and B in the gas phase
   D. Surface reaction between A in the gas phase and absorbed B

3. For a vapour phase catalytic reaction (A + B → P) which follows the Ridel mechanism and the reaction step is rate controlling, the rate of reaction is given by (reaction rate is irreversible, product also absorbs) ?

   A. -rA = (k . PA . PB)/(1 + KAPA + KPPP)
   B. -rA = (k . PA
   2 – k1PP)/(1 + KAPA + KPPP)
   C. -rA = (k . PA . PB)/(1 + KAPB + KBPB . KPPP)
   D. -rA = (k . PA . PB)/(1 + KAPA)

4. The rate expression for a heterogeneous catalytic reaction is given by, – rA = K.KA PA(1 + KA.PA + KR.PR), where K is surface reaction rate constant and KA and KR are absorption equilibrium constants of A and R respectively. If KR PR >> (1 + KA PA), the apparent activation energy EA is equal to (given E is the activation energy for the reaction and ΔHR and ΔHA are the activation energies of adsorption of R and A) ?

   A. E
   B. E + ΔHA
   C. E + ΔHA – ΔHR)
   D. ΔHA + ΔHR

5. Overall rate of reaction in a heterogeneous catalytic reaction depends upon the mass and energy transfer from the fluid to solid surface and its rate of reaction is usually ________________ the concentration of catalyst, if it does not entail a chain mechanism?

   A. Proportional to
   B. Independent of
   C. Inversely proportional to
   D. Proportional to the square of

6. Rate constant for a first order reaction does not depend upon reaction time, extent of reaction and the initial concentration of reactants; but it is a function of reaction temperature. In a chemical reaction, the time required to reduce the concentration of reactant from 100 gm moles/litre to 50 gm moles/litre is same as that required to reduce it from 2 gm moles/litre to 1 gm mole/litre in the same volume. Then the order of this reaction is ?

   A. 0
   B. 1
   C. 2
   D. 3

7. Second order consecutive irreversible reaction as shown in the bellow figure, were carried out in a constant volume isothermal batch reactor with different initial feed compositions. Reactor temperature was same in all the cases. In experiments where the ratio of concentration of B to that of A in the initial feed was less than 0.5, the concentration of B increased first, reached a maximum and then declined with time. However, for all experiments where this concentration ratio was 0.5 or above, concentration of B decreased monotonically with time right from the beginning. What is the ratio of the two rate constants (k1/k2) ?

   A. 1/4
   B. 1/2
   C. 2
   D. 4

8. If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the ________________ diffusion?

   A. Film
   B. Ash layer
   C. Pore
   D. None of these

9. Which one is the rate controlling step in a solid-gas non-catalytic reaction occurring at very high temperature ?

   A. Pore diffusion
   B. Film diffusion
   C. Ash layer diffusion
   D. Chemical reaction

10. For a gaseous phase reaction, rate of reaction is equal to K. CA . CB. If the volume of the reactor is suddenly reduced to 1/4th of its initial volume, then the rate of reaction compared to the original rate will be ______________ times?

    A. 8
    B. 16
    C. 1/8
    D. 1/16