Reaction Engineering (Set 2) Flashcards
Concepts necessary for reactor design, operation, and maintenance.
Space velocity
all (a), (b) and (c)
The rate of the chemical reaction A –>B doubles as the concentration of A i.e.., CA is doubled. If rate of reaction is proportional to CAn, then what is the value of n for this reaction ?
1
A reaction which is catalysed by a base is catalysed by all substances which have a tendency to
gain a proton
For a homogeneous reaction of nth order, the dimension of the rate constant is given by
(concentration)^1 - n/(time)
The fractional volume change between no conversion and complete conversion, for the isothermal gas phase reaction, 2A–>R, is
-0.5
The reaction in which one of the products of reaction acts as a catalyst is called a/an ____ reaction.
autocatalytic
A typical example of an exothermic reversible reaction conducted at high pressure in industry is
dehydration of ethanol.
Study of chemical kinetics is the easiest in the case of ____ reactions.
irreversible
In autocatalytic reactions,
one of the products acts as a catalyst.
Semibatch reactor is preferred, when a/an
all (a), (b), and (c).
Exposure of a photographic plate to produce a latent image is an example of ____ reaction.
both (b) and (c)
For identical flow rate, feed composition and for elementary first order reactions, ‘N’ equal sized mixed reactors in series with a total volume ‘V’ gives the same conversion as a single plug flow reactor of volume ‘V’ for constant density systems. This is true, when the value of ‘N’ is
∞
Helium-mercury method is used for the measurement of the ____ of the catalyst.
both (b) & (c).
What is the order of a chemical reaction whose rate is deter-mined by the variation of one concentration term only?
first
Pick out the wrong statement.
The order and molecularity of a complex reaction may not be the same.
The rate at which a chemical substance reacts is proportional to its
active mass
The exit age distribution of a fluid leaving a vessel (denoted by E) is used to study the extent of non-ideal flow in the vessel. The value of https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/467-387-1.png is
1
A plug-flow reactor is characterised by
presence of lateral mixing.
Three plug flow reactors (PFR’s) of 4, 5 & 6 m3 volumes are arranged in two branches as shown below in the figure. https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/468-389-1.png If the total feed rate is 300 tons/hr, then for the same conversion in each branch, the feed rate through branch II should be ____ tons/hr.
100
For a tubular reactor with space time ‘τ’ and residence time ‘θ’, the following statement holds good.
τ = θ , for an isothermic tubular reactor in which the density of the process fluid is constant.
Rate of an autocatalytic chemical reaction is a function of
all (a), (b) and (c).
Which of the following curves shows the effect of temperature on the extent of gas-solid adsorption at a given pressure?
Adsorption isobar
For an ideal mixed flow reactor (CSTR), the exit age distribution E(t) is given by
none of the above
Fluid flow in a real packed bed can be approximated as ____ model.
dispersion
For series reaction, the relative yield
both (a) and (c) hold good.
The ‘E’ curve for a non-ideal reactor defines the fraction of fluid having age between t and t + dt
at the outlet
To maximise the formation of R in the simultaneous reaction
A + B –> R , rR = 2CA^0.5.CB^2
A + B –> S , rS = 1.5 CA . CB
We should have
low CA, high CB
A reaction which is catalysed by an acid is also catalysed by any substance, which has a tendency to
lose a proton.
A stirred tank reactor compared to tubular-flow reactor provides
a. more uniform operating conditions.
b. permits operation at the optimum temperature for a long reaction time.
c. higher overall selectivity for a first order consecutive reaction.
all (a), (b) and (c)
A chemical reaction, A –>3B, is conducted in a constant pressure vessel. Starting with pure A, the volume of the reaction mixture increases 3 times in 6 minutes. The fractional conversion is
1
A catalyst inhibitor
all(a), (b) and (c).
In chamber process of sulphuric acid manufacture in industry, the gas phase oxidation of SO2 to SO3 is accomplished by a ____ reaction.
catalytic homogenous
If the rate of a chemical reaction becomes slower at a given temperature, then the
free energy of activation is higher.
The conversion XA and residence time data are collected for zero order liquid phase reaction in a stirred tank reactor. Which of the following will be a straight line ?
XA Vs . τ
The rate of the reaction, X–> Y, quadruples when the concentration of ‘X’ is doubled. The rate expression for the reaction is, r = K Cx^n, the value of ‘n’ in this case will be
2
The value of steric factor ‘P’ in the equation k = PZe^E/RT usually ranges from
1.0 to 10^-8
For a zero order reaction, the concentration of product increases with the
increase of reaction time.
Pick out the wrong statement.
A batch reactor can not be used to study the kinetics of catalytic reaction.
Effectiveness factor of a catalyst pellet is a measure of the ____ resistance.
pore diffusion
The rate expression for a heterogenous 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»_space; (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)
E + ΔHA - ΔHR)