Chemical Reaction Engineering Flashcards
Which of the following will give maximum gas conversion ?
Semi-fluidised bed reactor
__________ explains the mechanism of catalysis.
Activated complex theory
From among the following, choose one which is not an exothermic process.
Catalytic cracking
The fractional volume change of the system for the isothermal gas phase reaction, A 3B , between no conversion and complete conversion is
2
A catalyst
lowers the activation energy of reacting molecules
For high conversion in a highly exothermic solid catalyzed reaction, use a __________ bed reactor.
fluidised bed reactor followed by a fixed
For every 10°C rise in temperature, the rate of chemical reaction doubles. When the temperature is increased from 30 to 70°C, the rate of reaction increases __________ times.
16
The single parameter model proposed for describing non-ideal flow is the __________ model.
both (a) & (b)
A first order reaction requires two equal sized CSTR. The conversion is
more when they are connected in series.
The most unsuitable reactor for carrying out reactions in which high reactant concentration favours high yields is
backmix reactor
Pick out the wrong statement pertaining to space velocity of flow reactors.
The space velocity of 3 hr-1 means that one third reactor volume of feed at specified conditions are being fed into the reactor.
A reactor is generally termed as an autoclave, when it is a
high pressure batch reactor.
6 gm of carbon is burnt with an amount of air containing 18 gm oxygen. The product contains 16.5 gms CO2 and 2.8 gms CO besides other constituents. What is the degree of conversion on the basis of disappearance of limiting reactant ?
95%
The rate constant of a chemical reaction decreases by decreasing the
temperature
__________ is the response curve for a step input signal from a reactor.
S-curve
‘If the catalyst pore size is small in comparison with the mean free path, collisions with the pore wall controls the process’. The diffusivity under this condition is called ‘Knudsen diffusivity’, which is affected by the
temperature
Which of the following is the most suitable for very high pressure gas phase reaction ?
Tubular flow reactor
The reaction between oxygen and organic material is a/an __________ reaction.
exothermic
With decrease in temperature, the equilibrium conversion of a reversible endother-mic reaction
decreases
In an exothermic chemical reaction, the reactants compared to the products have
more energy
A reversible liquid phase endothermic reaction is to be carried out in a plug flow reactor. For minimum reactor volume, it should be operated such that the temperature along the length
is at the highest allowable temperature throughout.
A batch reactor is suitable for
liquid phase reactions
For a heterogeneous catalytic reaction
free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction
free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction
decrease in activation energy.
A catalyst loses its activity due to
all (a), (b) and (c)
N’ plug flow reactors in series with a total volume ‘V’ gives the same conversion as a single plug flow reactor of volume ‘V’ for __________ order reactions.
any
Specific rate constant for a second order reaction
both (b) and (c).
For a zero order chemical reaction, the
all (a), (b) and (c).
Radioactive decay follows __________ order kinetics.
first
The excess energy of reactants in a chemical reaction required to dissociate into products is termed as the __________ energy.
activation
For a solid catalyzed chemical reaction, the effectiveness of solid catalyst depends upon the __________ adsorption.
chemical
Pick out the correct statement.
A catalyst lowers the activation energy of the reacting molecules.
The dimensions of rate constant for reaction 3A B are (l/gm mole)/min. Therefore the reaction order is
2
Pick out the correct statement
Reactions with high activation energies are very temperature sensitive.
If the time required to complete a definite fraction of reaction varies inversely as the concentration of the reactants, then the order of reaction is
2
Sulphuric acid is used as a catalyst in the
alkylation of hydrocarbons.
Fractional conversion __________ with increase in pressure for ammonia synthesis reaction i.e., N2 + 3H2 2NH3.
increases
Pick out the wrong statement.
Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a particular duty.
The reason why a catalyst increases the rate of reaction is that, it
decreases the energy barrier for reaction.
A first order irreversible reaction, A B is carried out separately in a constant volume as well as in a variable volume reactor for a particular period. It signifies that __________ in the two reactors.
conversion in both will be the same but concentrations will be different
When the density of the reaction mixture is constant in a chemical reaction, the ratio of the mean residence time to space time is
1
In an ideal tubular-flow reactor
all (a), (b) and (c).
__________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction.
Chemical reaction
An autothermal reactor is
completely self-supporting in its thermal energy requirements.
The rate constant of a first order reaction depends on the
temperature.
A reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
autocatalytic
Conversion increases with increase in temperature in case of a an __________ reaction.
reversible endothermic
A photochemical reaction is __________ light.
initiated by
Pick out the wrong statement.
In a continuous flow reactor, uniform concentration can not be maintained throughout the vessel even in a well agitated system.
In a/an __________ reactor, there is exchange of heat with the surroundings with sizeable temperature variation.
non-adiabatic
‘Unreacted core model’ represents the reaction involving
roasting of sulphide ores.
If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the __________ diffusion.
film
The units of frequency factor in Arhenious equation
are the same as those of the rate constant.
Which of the following is not a chemical step in a fluid solid catalytic reaction
none of these
In case of __________ reactions, the reaction rate does not decrease appreciably as the reaction proceeds.
auto catalytic
For nearly isothermal operation involving large reaction time in a liquid-phase reaction, the most suitable reactor is a __________ reactor.
stirred tank
B.E.T. method can be used to determine the __________ of a porous catalyst.
surface area
Which of the following is an independent variable for a batch tank reactor with uniform concentration and temperature ?
Time
For reactions in parallel viz A P (desired product) and A Q (unwanted product), if the order of the desired reaction is higher than that of the undesired reaction, a
both (a) and (b).
In a reversible chemical reaction having two reactants in equilibrium, if the concentration of the reactants are doubled, then the equilibrium constant will
remain the same
The equilibrium constant of a catalytic chemical reaction __________ due to the presence of a catalyst
remains unaffected
The rate constant of a chemical reaction increases by increasing the
temperature
The catalytic activity of enzymes is due to their capacity to lower the __________ energy.
activation
A first order reaction requires two unequal sized CSTR. Which of the following gives higher yield ?
Either of the arrangement (a) or (b) will give the same yield.
Pick out the correct statement.
A lower temperature favours the reaction of lower activation energy
A batch reactor is characterized by
variation in extent of reaction and properties of the reaction mixture with time.
When a catalyst increases the rate of forward reaction, the value of rate constant
increases
Rate determining step in a reaction consisting of a number of steps in series is the __________ step.
slowest