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

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
by

1 Answer

Answer :

(A) Film
by

Related questions

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

Description : 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

Last Answer : (B) Film diffusion

__________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction. (A) Gas film diffusion (B) Ash diffusion (C) Chemical reaction (D) None of these

Description : __________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction. (A) Gas film diffusion (B) Ash diffusion (C) Chemical reaction (D) None of these

Last Answer : (C) Chemical reaction

Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction?(A) Ash resistance (B) Gas film and pore surface diffusion resistances for reactants (C) Surface phenomenon resistance (D) Gas film and pore surface diffusion resistances for products

Description : Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction? (A) Ash resistance (B) Gas film and pore surface diffusion resistances for reactants (C) Surface phenomenon resistance (D) Gas film and pore surface diffusion resistances for products

Last Answer : (A) Ash resistance

For the non catalytic reaction of particles with surrounding fluid, the same needed to achieve the same fractional conversion for particles of different unchanging sizes is proportional to the particle diameter, when the __________ is the controlling resistance. (A) Film diffusion (B) Diffusion through ash layer (C) Chemical reaction (D) Either (A), (B) or (C)

Description : For the non catalytic reaction of particles with surrounding fluid, the same needed to achieve the same fractional conversion for particles of different unchanging sizes is proportional to the particle diameter, when the ... through ash layer (C) Chemical reaction (D) Either (A), (B) or (C)

Last Answer : (C) Chemical reaction

For the non-catalytic reaction of particles with surrounding fluid, the time needed to achieve the same fractional conversion for particles of different but unchanging sizes is proportional to the square of particle diameter, when the __________ is the controlling resistance. (A) Film diffusion (B) Diffusion through ash layer (C) Chemical reaction (D) Either (A), (B) or (C)

Description : For the non-catalytic reaction of particles with surrounding fluid, the time needed to achieve the same fractional conversion for particles of different but unchanging sizes is proportional to the square of particle diameter, ... through ash layer (C) Chemical reaction (D) Either (A), (B) or (C)

Last Answer : (B) Diffusion through ash layer

If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst (A) Porosity is very important (B) Porosity is of less importance (C) Internal surface area is utilised efficiently (D) None of these

Description : If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst (A) Porosity is very important (B) Porosity is of less importance (C) Internal surface area is utilised efficiently (D) None of these

Last Answer : (B) Porosity is of less importance

Pick out the correct statement. (A) A lower temperature favours the reaction of lower activation energy (B) The dispersion number for a reactor/vessel is uL/D (C) The rate controlling step in a reaction involving many steps is the fastest step (D) Pore volume and porosity of a catalyst is measured by Brunauer￾Emmett-Teller (BET) technique

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Last Answer : (A) A lower temperature favours the reaction of lower activation energy

Effectiveness factor of a catalyst pellet is a measure of the __________ resistance. (A) Pore diffusion (B) Gas film (C) Chemical reaction (D) None of these

Description : Effectiveness factor of a catalyst pellet is a measure of the __________ resistance. (A) Pore diffusion (B) Gas film (C) Chemical reaction (D) None of these

Last Answer : (A) Pore diffusion

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 (A) Surface Kc /(1 + TS ) reaction between absorbed A and B in the gas phase (B) Surface reaction between absorbed A and absorbed B (C) Surface reaction between A in the gas phase and absorbed B(D) Desorption of C

Description : 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 (A) Surface Kc /(1 + TS ) ... A and absorbed B (C) Surface reaction between A in the gas phase and absorbed B (D) Desorption of C

Last Answer : (D) Desorption of C

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

Description : 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

Last Answer : (D) ED/2

What is the Thiele modulus of the solid catalysed first order reaction as shown in the bellow figure, if the pore diffusion offers negligible resistance to reaction? (A) < 5 (B) < 0.5(C) > 1 (D) 5

Description : What is the Thiele modulus of the solid catalysed first order reaction as shown in the bellow figure, if the pore diffusion offers negligible resistance to reaction? (A) < 5 (B) < 0.5 (C) > 1 (D) 5

Last Answer : (B) < 0.5

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

Description : 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

Last Answer : (A) tan hT/T

Which of the following is not a chemical step in a fluid solid catalytic reaction? (A) Surface chemical reaction (B) Adsorption (C) Desorption (D) None of these

Description : Which of the following is not a chemical step in a fluid solid catalytic reaction? (A) Surface chemical reaction (B) Adsorption (C) Desorption (D) None of these

Last Answer : (D) None of these

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 doesnot entail a chain mechanism.(A) Proportional to(B) Independent of(C) Inversely proportional to(D) Proportional to the square o

Description : 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 ... to (B) Independent of (C) Inversely proportional to (D) Proportional to the square o

Last Answer : (A) Proportional to

Non-catalytic fluid-solid reactions are represented by __________ model. (A) Continuous reaction (B) Unreacted core (C) Both (A) and (B) (D) Neither (A) and (B)

Description : Non-catalytic fluid-solid reactions are represented by __________ model. (A) Continuous reaction (B) Unreacted core (C) Both (A) and (B) (D) Neither (A) and (B)

Last Answer : (C) Both (A) and (B)

__________ resistance is not involved in the combustion of a carbon particle. (A) Gas film (B) Ash (C) Chemical reaction (D) None of these

Description : __________ resistance is not involved in the combustion of a carbon particle. (A) Gas film (B) Ash (C) Chemical reaction (D) None of these

Last Answer : (B) Ash

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 reaction in catalyst of large pore diameter (C) Slow reactions in catalyst of small pore diameter (D) Slow reactions in catalyst of large pore diameter

Description : 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 reaction in catalyst ... reactions in catalyst of small pore diameter (D) Slow reactions in catalyst of large pore diameter

Last Answer : (C) Slow reactions in catalyst of small pore diameter

If Thiele modulus is __________, then the pore diffusion resistance in a catalyst may be considered as negligible. (A) 0 (B) ∞ (C) < 0.5 (D) > 0.5

Description : If Thiele modulus is __________, then the pore diffusion resistance in a catalyst may be considered as negligible. (A) 0 (B) ∞ (C) < 0.5 (D) > 0.5

Last Answer : (C) < 0.5

Bulk diffusion in catalyst pore __________ with increase in pressure. (A) Increases (B) Decreases (C) Remains unchanged (D) Increases exponentially

Description : Bulk diffusion in catalyst pore __________ with increase in pressure. (A) Increases (B) Decreases (C) Remains unchanged (D) Increases exponentially

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Pick out the correct statement. (A) Higher hold up of the solid in the rotary dryer results in better exposure of the solids to the gas (B) The 'Hatta number' is important in problems involving gas absorption without chemical reaction (C) For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion (D) Total reflux in case of distillation operation requires infinite number of plates for a binary system separation

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Pick out the wrong statement. (A) The controlling resistance in case of heating of air by condensing steam is in the air film (B) The log mean temperature difference (LMTD) for counter flow and parallel flow can be theoretically same when any one of the fluids (hot or cold fluid) passes through the heat exchanger at constant temperature (C) In case of a 1 - 2 shell and tube heat exchanger, the LMTD correction factor value increases sharply, when a temperature cross occurs (D) Phase change in case of a pure fluid at a given pressure from liquid to vapor or vice-versa occurs at saturation temperature

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The drying time between fixed moisture content within diffusion controlled 'falling rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 2 (D) T

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In chamber process of sulphuric acid manufacture in industry, the gas phase oxidation of SO2 to SO3 is accomplished by a __________ reaction. (A) Non-catalytic homogeneous (B) Non-catalytic heterogeneous (C) Catalytic homogenous (D) Catalytic heterogeneous

Description : In chamber process of sulphuric acid manufacture in industry, the gas phase oxidation of SO2 to SO3 is accomplished by a __________ reaction. (A) Non-catalytic homogeneous (B) Non-catalytic heterogeneous (C) Catalytic homogenous (D) Catalytic heterogeneous

Last Answer : (C) Catalytic homogenous

__________ catalytic reaction is involved in the thermal cracking of gas oil. (A) Homogeneous (B) Non-Homogeneous (C) Heterogeneous (D) Non-Heterogeneous

Description : __________ catalytic reaction is involved in the thermal cracking of gas oil. (A) Homogeneous (B) Non-Homogeneous (C) Heterogeneous (D) Non-Heterogeneous

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Helium-mercury method can be used to determine the __________ of the catalyst particle. (A) Pore volume (B) Solid density (C) Porosity (D) All (A), (B), & (C)

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Last Answer : (D) All (A), (B), & (C)

. B.E.T. method can be used to determine the __________ of a porous catalyst. (A) Solid density (B) Pore volume (C) Surface area (D) All (A), (B) and (C)

Description : . B.E.T. method can be used to determine the __________ of a porous catalyst. (A) Solid density (B) Pore volume (C) Surface area (D) All (A), (B) and (C)

Last Answer : (C) Surface area

Pick out the wrong statement. (A) Alkylation produces a larger iso-paraffin (having higher octane number) from the reaction of an olefin with smaller iso-paraffin (B) Catalytic alkylation processes use HF, AlCl3 & H2SO4 as Catalysts (C) All the alkylation processes use very high temperature (> 1000°C) (D) Gasoline having an octane number of 90 can be produced by alkylation process

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Last Answer : (C) All the alkylation processes use very high temperature (> 1000°C)

Which of the following factors control the deactivation of a porous catalyst pellet? (A) Decay reactions (B) Pore diffusion (C) Form of surface attack by poison (D) All (A), (B) and (C)

Description : Which of the following factors control the deactivation of a porous catalyst pellet? (A) Decay reactions (B) Pore diffusion (C) Form of surface attack by poison (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

The importance of diffusion in a catalyst are increased by (A) Large catalyst particle size (B) An active surface of the catalyst (C) Small pore diameter (D) All (A), (B) and (C)

Description : The importance of diffusion in a catalyst are increased by (A) Large catalyst particle size (B) An active surface of the catalyst (C) Small pore diameter (D) All (A), (B) and (C)

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Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface? (A) Liquid density (B) Liquid viscosity (C) Hot surface temperature (D) Interfacial tension

Description : Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface? (A) Liquid density (B) Liquid viscosity (C) Hot surface temperature (D) Interfacial tension

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When the reaction occurs in the diffusion controlled region, the apparent activation energy as measured is only __________ the true value. (A) Twice (B) Half (C) Equal (D) None of these

Description : When the reaction occurs in the diffusion controlled region, the apparent activation energy as measured is only __________ the true value. (A) Twice (B) Half (C) Equal (D) None of these

Last Answer : (B) Half

Gasification of the solid fuel converts its organic part into combustible by interaction with air/oxygen and steam so as to obtain a secondary gaseous fuel of high calorific value having no ash. Gasification reactions are normally carried out at about __________ °C. (A) 400-500 (B) 900-1000 (C) 1400-1500 (D) 1700-1800

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Last Answer : (B) 900-1000

In case of __________ reactions, the reaction rate does not decrease appreciably as the reaction proceeds. (A) Catalytic (B) Parallel (C) Series (D) Auto catalytic

Description : In case of __________ reactions, the reaction rate does not decrease appreciably as the reaction proceeds. (A) Catalytic (B) Parallel (C) Series (D) Auto catalytic

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Film boiling occurs at __________ pressure. (A) Atmospheric (B) Sub-atmospheric (C) Negative (D) Very high

Description : Film boiling occurs at __________ pressure. (A) Atmospheric (B) Sub-atmospheric (C) Negative (D) Very high

Last Answer : (D) Very high

Pick out the wrong statement. (A) The binary diffusivity in liquids is of the order of 10 -5 cm2 /sec (B) Molecular diffusion in solid is much faster than that in liquids (C) Particles movement from higher concentration to lower concentration takes place in diffusion process (D) According to Poiseuille's law, the permeability decreases with increase in temperature for flow of a gas through a given capillary

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Last Answer : (B) Molecular diffusion in solid is much faster than that in liquids

The reason for excessive clinker formation in gas producers is the (A) Use of coal/coke containing a high % of fines and ash (B) Use of fuel having too low an ash fusion temperature (C) Development of hot spots in the fuel bed and an abnormally high rate of gasification (D) All (A), (B) and (C)

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Last Answer : (D) All (A), (B) and (C)

Steam reforming of naphtha produces ammonia synthesis gas. This is a/an __________ process. (A) Autocatalytic (B) Endothermic (C) Exothermic (D) Non-catalytic

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Last Answer : (B) Endothermic

Which of the following is a controlling factor in very fast heterogeneous reaction? (A) Heat and mass transfer effects (B) Pressure (C) Temperature (D) Composition of reactant

Description : Which of the following is a controlling factor in very fast heterogeneous reaction? (A) Heat and mass transfer effects (B) Pressure (C) Temperature (D) Composition of reactant

Last Answer : (A) Heat and mass transfer effects

The rate controlling step in the manufacture of silicone rubber is the (A) Polymer termination step (B) Condensation of siloxane to silicone (C) Initial hydrolysis of silicone monomer (D) None of these

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Last Answer : (C) Initial hydrolysis of silicone monomer

Controlling heat transfer film co-efficient is the one, which offers __________ resistance to heat transfer. (A) No (B) The least (C) The largest (D) Lower

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Last Answer : (C) The largest

Pick out the wrong statement. (A) Exit age description function (E) and internal age distribution function (I) are related as, E = -(dI/dθ) (B) Chemisorption studies are useful in the determination of catalyst surface area and pore size distribution (C) A higher temperature favours the reaction of higher activation energy (D) A catalyst increases the potential energy barrier over which the reactants must pass to form products

Description : Pick out the wrong statement. (A) Exit age description function (E) and internal age distribution function (I) are related as, E = -(dI/dθ) (B) Chemisorption studies are useful in the ... energy (D) A catalyst increases the potential energy barrier over which the reactants must pass to form products

Last Answer : (D) A catalyst increases the potential energy barrier over which the reactants must pass to form products

If air (a non-condensing gas) is present in a condensing vapor stream, it will __________ the condensation rate of vapor. (A) Increase (B) Decrease (C) Not affect (D) Increase the condensing film co-efficient as well as

Description : If air (a non-condensing gas) is present in a condensing vapor stream, it will __________ the condensation rate of vapor. (A) Increase (B) Decrease (C) Not affect (D) Increase the condensing film co-efficient as well as

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Brunauer, Emmet and Teller (BET) equation is used to determine the specific surface area of a porous particle but not the pore volume & the porosity of the catalyst bed. Which of the following postulates is not used to derive BET equation? (A) Langmuir's assumption applies to every adsorbed layer (B) There is no dynamic equilibrium between successive layer (C) The adsorbed layer may be polymolecular in thickness and the heat of adsorption in each layer (except the first one) is involved in each of the evaporation process (D) None of these

Description : Brunauer, Emmet and Teller (BET) equation is used to determine the specific surface area of a porous particle but not the pore volume & the porosity of the catalyst bed. Which of the following postulates ... (except the first one) is involved in each of the evaporation process (D) None of these

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In catalytic cracking, the (A) Gasoline obtained has a very low octane number (B) Pressure & temperature is very high (C) Gasoline obtained has very high aromatic content (D) Gasoline obtained has very high amount of gum forming compounds

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Description : Catalytic converter used for controlling pollution is used in

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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) ∞

Description : 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) ∞

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Enzymes are different from catalysts in (A) Being proteinaceous (B) Not used up in reaction (C) Functional at high temperature (D) Having high rate of diffusion

Description : Enzymes are different from catalysts in (A) Being proteinaceous (B) Not used up in reaction (C) Functional at high temperature (D) Having high rate of diffusion

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