0% 0 Chemical Reaction Quiz 6 1 / 50 Space time equals the mean residence time___________? For narrow diameter tubular reactor For CSTR For large diameter tubular reactor When the density of the reaction mixture is constant 2 / 50 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 ? 0 1 3 2 3 / 50 The catalytic activity of enzymes is due to their capacity to lower the _______ energy? Activation Potential None of these Kinetic 4 / 50 Pick out the wrong statement? The differential method of analysing kinetic data requires more accurate or larger amounts of data The ratio of volumes of plug flow reactor to that of mixed reactor is always less than one for identical feed composition, flow rate, conversion and for all positive reaction orders The integral method of analysing kinetic data is used when the data is scattered When the reaction rate is independent of temperature, the reaction is said to be of zero order 5 / 50 Signal normally used to study non-ideal flow by stimulus response technique is ________ input? Pulse Step Neither A. nor B. Both A. & B. 6 / 50 Space velocity______? Is the maximum feed rate per unit volume of reactor for a given conversion All A., B. and C. Is a measure of the ease of the reaction Describes the extensive operating characteristics of a tubular flow reactor 7 / 50 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) ? 4-Jan 2-Jan 4 2 8 / 50 The dispersion number of perfect mixed flow is___________? 0 > 150 < 2100 ? 9 / 50 Radioactive decay follows _______ order kinetics? Second Zero First Third 10 / 50 Recycling back of outlet stream to the reactor from an ideal CSTR carrying out a first order liquid phase reaction will result in _______ in conversion? Either A. or B., depends on the type of reaction Increase No change Decrease 11 / 50 Rate of a gaseous phase reaction is given by the reaction shown in the bellow figure. The unit of rate constant is___________? (atm)-1.(hr)-1 atm.(hr)-1 (hr)-1 (atm)-1 12 / 50 Sometimes, batch process is preferred over continuous process, when the product_____? Quality & yield cannot be achieved in continuous processes, because of long residence time Both A. & B. Sales demand is fluctuating Neither A. nor B. 13 / 50 Pick out the wrong statement? Catalytic activity of enzyme catalysed reactions which is affected by temperature, pH value & chemical agents, is maximum at a temperature of about 45?C Most of the enzyme catalysed reactions involve at least two substrates Equilibrium concentrations in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & products Enzymes help in increasing the activation energy of the reaction 14 / 50 The concentration of A in a first order reaction, A ? B, decreases_______? Exponentially with time Linearly with time Very abruptly towards the end of the reaction Logarithmically with time 15 / 50 Rate of a chemical reaction is not affected by the______? Catalyst Reactant?s concentration Temperature Number of molecules of reactants taking part in the reaction 16 / 50 Sulphuric acid is used as a catalyst in the________? Hydrogenation of oils None of these Gas phase oxidation of SO2 in chamber process Alkylation of hydrocarbons 17 / 50 Space time in flow reactor is______? The reciprocal of the space velocity A measure of its capacity Both A. and B. Usually equal to the residence time 18 / 50 Pure ethanol vapor is fed to a reactor packed with alumina catalyst, at the rate of 100 kmole / hr. The reactor products comprise: ethylene: 95 kmole / hr, water vapour: 97.5 k mole / hr and diethyl ether: 2.5 kmole/hr. The reactions occuring can be represented by: C2H5OH ? C2H4 + H2O 2C2H5OH ? C2H5 ? O ? C2H5 + H2O The percent conversion of ethanol in the reactor is_________? 100 95 2.5 97.5 19 / 50 Reaction rate of a first order reaction, which is half completed in 23 minutes will be __________? 0.05 min-1 0.03 hr-1 0.03 min-1 0.03 sec-1 20 / 50 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) ? L ?(K/D1) 1/[L?(K/D1)] 1 ? 21 / 50 The catalyst in a first order chemical reaction changes the__________? Equilibrium constant Activation energy Heat of formation of the product Heat of reaction 22 / 50 Shift conversion reaction__________? Is non-catalytic Converts CO to CO2 with steam Converts N2 and H2 into NH3 Is highly exothermic 23 / 50 Promoter_______? Increases the number of active centres by increasing the unevenness of catalyst surface and by creating discontinuities in the crystals All A., B. and C. Initiates a chemical reaction and is a catalyst by itself Alters the position of equilibrium in a reversible reaction 24 / 50 Rate constant ?k? and absolute temperature ?T? are related by collision theory (for bimolecular) as________? k ? T1.5 k ? T k ? ?T k ? exp(-E/RT) 25 / 50 Specific rate constant for a second order reaction___________? Is independent of temperature Varies with temperature Depends on the nature of the reactants Both B. and C. 26 / 50 The ?E? curve for a non-ideal reactor defines the fraction of fluid having age between t and t + dt _______? At the inlet Averaged over the inlet and outlet In the reactor At the outlet 27 / 50 The catalytic converter for conversion of SO2 to SO3 by contact process should have a feed with SO2 content between_____? 2-5 % 7-10 % 12-15 % 20-25 % 28 / 50 Rate of a chemical reaction is independent of the concentration of the reactants for a __________ reaction? Zero order Third order None of these Consecutive 29 / 50 Pick the WRONG design guideline for a reactor in which the reactions, A ? R (desired) and A ? S (undesired) are to take place. The ratio of the reaction rates is rR/rS = (k1/k2). CA a-b ? Use batch reactor or plug flow reactor, when a > b Avoid recycle, when a > b Use high pressure and eliminate inerts, when a > b Use CSTR with a high conversion, when a > b 30 / 50 Pick out the wrong statement? A catalyst increases the potential energy barrier over which the reactants must pass to form products Chemisorption studies are useful in the determination of catalyst surface area and pore size distribution Exit age description function E. and internal age distribution function (I) are related as, E = -(dI/d?) A higher temperature favours the reaction of higher activation energy 31 / 50 Pick out the wrong statement? According to the penetration theory, the mass transfer co-efficient decreases, if the exposure time of an eddy to the solute decreases Transition state theory approaches the problem of calculating reaction rates by concentrating on the idea of activated complexes In a first order reaction, A ? products; the reaction becomes slower as it proceeds, because the concentration of A decreases and the rate is proportional to the concentration of A If the rate of an irreversible reaction, A + B ? 2C is k.CA.CB, then the reaction is always elementary 32 / 50 The catalyst in a second order reversible reaction increases the rate of the forward reaction_____? And backward reaction equally Only And decreases that of backward reaction To a greater extent than that of the backward reaction 33 / 50 Reaction of benzene with chlorine gas to produce tri-chlorobenzene exemplifies a/an _______ reaction? Parallel None of these Elementary Consecutive 34 / 50 The eddy diffusivity for a liquid in plug flow must be__________? Between 0 and 1 1 0 ? 35 / 50 Reactions with high activation energy are_______? Very temperature sensitive Always irreversible Always reversible Temperature insensitive 36 / 50 Rate of an autocatalytic chemical reaction is a function of _____? All A., B. and C. Pressure only Temperature only Composition only 37 / 50 The conversion for a first order liquid phase reaction. A ? B in a CSTR is 50%. If another CSTR of the same volume is connected in series, then the % conversion at the exit of the second reactor will be_______? 100 75 90 60 38 / 50 The conversion of a reactant, undergoing a first order reaction, at a time equal to three times the half life of the reaction is ? 0.425 0.875 Data insufficient to calculate 0.5 39 / 50 Pick out the wrong statement? Presence of inerts affects the equilibrium conversion of Use of different catalysts in a reversible catalytic chemical reaction does not change the equilibrium composition Alumina is added as a promoter to iron catalyst in ammonia synthesis reaction Activation energy for a reaction is obtained from the intercept of the Arrhenius plot 40 / 50 Pick out the wrong statement? A very high value of equilibrium constant, K (K >> 1) indicates that the reaction is practically irreversible in nature The intercept of the Arrhenius plot is called the ?activation energy? Non-ideal flow takes place in reactors due to recycling, channeling or by creation of stagnant regions A particular chemical reaction is more temperature sensitive at low temperatures 41 / 50 Sum of the powers of the concentration terms in the rate equation is called the ______ of the reaction? Order None of these Overall order Molecularity 42 / 50 The conversion for a second order, irreversible reaction (constant volume) as shown in the bellow figure, in batch mode is given by_______? 1/(1 + k2 . CA0 . t) (k2 . CA0 . t)/ (1 + k2 . CA0 . t) (k2 . CA0 . t)/ (1 + k2 . CA0 . t)2 (k2 . CA0 . t)2/ (1 + k2 . CA0 . t) 43 / 50 The dimensions of rate constant for reaction 3A ? B are (l/gm mole)/min. Therefore the reaction order is________? 0 2 3 1 44 / 50 Promoter is added to the catalyst to improve its______? Porosity None of these Surface area Sensitivity 45 / 50 The conversion in a mixed reactor/accomplishing a reaction A ? 3R is 50% when gaseous reactant ?A? is introduced at the rate of 1 litre/second and the leaving flow rate is 2 litres/second. The holding time for this operation is ________ second? 2 1 3 0.5 46 / 50 Reverse reaction in a chemical equilibrium is favoured by the_________? None of these Removal of one of the products regularly Increase in the concentration of one of the products Increase in the concentration of one of the reactants 47 / 50 Slurry reactors are characterised by the__________? Neither A. nor B. Lack of intraparticle diffusion resistance Both A. and B. Presence of two mobile phases 48 / 50 Rate of a chemical reaction is not influenced by the___________? Reactants concentration Number of molecules of reactants taking part in a reaction Catalyst Temperature 49 / 50 Rate determining step in a reaction consisting of a number of steps in series is the _______ step? Slowest Fastest Intermediate Data insufficient; can?t be predicted 50 / 50 Semibatch reactor is preferred, when a/an___________? All A., B., and C. A gas is to be reacted with liquid (e.g. hydrogenation of fat) A highly exothermic reaction is to be controlled Undesirable side reaction (at high concentration of one of the reactants) is to be avoided Provide Your Information Your score is The average score is 0% LinkedIn Facebook Twitter 0% Restart quiz Send feedback Share on facebook Facebook Share on twitter Twitter Share on whatsapp WhatsApp PrevChemical Reaction Quiz 5 Chemical Reaction Quiz 7Next
