If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst___________________?

Related Mcqs:

1. Effectiveness factor E. of a catalyst pellet is defined as, E = (actual rate within pore of the catalyst)/(rate if not snowed by pore diffusion), Effectiveness factor for a first order reaction is given by (where, T = Thiele modulus) ___________________?

   A. tan hT/T
   B. tan T/T
   C. tan hT/tan T
   D. None of these

2. 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

3. A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction A → B. Film mass transfer resistance is negligible and pore diffusion of A is rate controlling. The effectiveness factor of the catalyst is reported as 7/8. Which of the following statement is true?

   A. Inner catalyst core of radius R/8 does not participate in reaction
   B. Inner catalyst core of radius R/2 does not participate in reaction
   C. Inner catalyst core of radius 7R/8 does not participate in reaction
   D. Effectiveness factor for a zero order reaction cannot be 7/8 as it must always be 1

4. The effectiveness factor for large value of Thiele modulus [L√(K/D1)] of a solid catalysed first order reaction is equal to (where, L = length of the reactor, cm, D1 = diffusion co-efficient, cm2/second) ?

   A. L √(K/D1)
   B. 1/[L√(K/D1)]
   C. 1
   D. ∞

5. 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

6. A reaction which is catalysed by a base is catalysed by all substances which have a tendency to_______________________?

   A. Lose a proton
   B. Gain a proton
   C. Gain an electron
   D. None of these

7. A reaction which is catalysed by an acid is also catalysed by any substance, which has a tendency to _________________?

   A. Lose a proton
   B. Gain a proton
   C. Lose an electron
   D. None of these

8. For a solid catalysed chemical reaction, the effectiveness of solid catalyst depends upon the ______________ adsorption?

   A. Physical
   B. Chemical
   C. Both A. and B.
   D. Neither A. nor B.

9. 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)

10. If the pore diffusion controls in a catalytic reaction, the apparent activation energy Ea is equal to___________________?

    A. The intrinsic activation energy E
    B. (E + ED) where ED is activation due to diffusion
    C. (E + ED)/2
    D. ED/2