Chemical Reaction Quiz 6

1 / 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

(hr)-1

(atm)-1

atm.(hr)-1

2 / 50

Rate constant ?k? and absolute temperature ?T? are related by collision theory (for bimolecular) as________?

k ? ?T

k ? T1.5

k ? exp(-E/RT)

k ? T

3 / 50

Rate of a chemical reaction is not affected by the______?

Catalyst

Temperature

Reactant?s concentration

Number of molecules of reactants taking part in the reaction

4 / 50

Shift conversion reaction__________?

Converts N2 and H2 into NH3

Is non-catalytic

Converts CO to CO2 with steam

Is highly exothermic

5 / 50

Pick out the wrong statement?

When the reaction rate is independent of temperature, the reaction is said to be of zero order

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

The differential method of analysing kinetic data requires more accurate or larger amounts of data

6 / 50

Rate of a chemical reaction is not influenced by the___________?

Temperature

Number of molecules of reactants taking part in a reaction

Catalyst

Reactants concentration

7 / 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 ?

Avoid recycle, when a > b

Use batch reactor or plug flow reactor, when a > b

Use high pressure and eliminate inerts, when a > b

Use CSTR with a high conversion, when a > b

8 / 50

The ?E? curve for a non-ideal reactor defines the fraction of fluid having age between t and t + dt _______?

In the reactor

At the outlet

Averaged over the inlet and outlet

At the inlet

9 / 50

Specific rate constant for a second order reaction___________?

Both B. and C.

Depends on the nature of the reactants

Is independent of temperature

Varies with temperature

10 / 50

Space time in flow reactor is______?

Usually equal to the residence time

The reciprocal of the space velocity

A measure of its capacity

Both A. and B.

11 / 50

Rate of an autocatalytic chemical reaction is a function of _____?

All A., B. and C.

Composition only

Temperature only

Pressure only

12 / 50

The conversion for a second order, irreversible reaction (constant volume) as shown in the bellow figure, in batch mode is given by_______?

(k2 . CA0 . t)2/ (1 + k2 . CA0 . t)

(k2 . CA0 . t)/ (1 + k2 . CA0 . t)2

(k2 . CA0 . t)/ (1 + k2 . CA0 . t)

1/(1 + k2 . CA0 . t)

13 / 50

Rate determining step in a reaction consisting of a number of steps in series is the _______ step?

Slowest

Intermediate

Data insufficient; can?t be predicted

Fastest

14 / 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?

0.5

15 / 50

Pick out the wrong statement?

Presence of inerts affects the equilibrium conversion of

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

Use of different catalysts in a reversible catalytic chemical reaction does not change the equilibrium composition

16 / 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

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

Transition state theory approaches the problem of calculating reaction rates by concentrating on the idea of activated complexes

If the rate of an irreversible reaction, A + B ? 2C is k.CA.CB, then the reaction is always elementary

17 / 50

Promoter_______?

Initiates a chemical reaction and is a catalyst by itself

Alters the position of equilibrium in a reversible reaction

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.

18 / 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) ?

1/[L?(K/D1)]

L ?(K/D1)

19 / 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

20 / 50

Rate of a chemical reaction is independent of the concentration of the reactants for a __________ reaction?

Consecutive

Third order

Zero order

None of these

21 / 50

Reactions with high activation energy are_______?

Very temperature sensitive

Temperature insensitive

Always reversible

Always irreversible

22 / 50

Space velocity______?

Is the maximum feed rate per unit volume of reactor for a given conversion

Describes the extensive operating characteristics of a tubular flow reactor

Is a measure of the ease of the reaction

All A., B. and C.

23 / 50

The concentration of A in a first order reaction, A ? B, decreases_______?

Logarithmically with time

Very abruptly towards the end of the reaction

Linearly with time

Exponentially with time

24 / 50

Promoter is added to the catalyst to improve its______?

None of these

Surface area

Sensitivity

Porosity

25 / 50

The catalytic converter for conversion of SO2 to SO3 by contact process should have a feed with SO2 content between_____?

20-25 %

12-15 %

7-10 %

2-5 %

26 / 50

The catalytic activity of enzymes is due to their capacity to lower the _______ energy?

None of these

Kinetic

Activation

Potential

27 / 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?

Decrease

Increase

No change

Either A. or B., depends on the type of reaction

28 / 50

Signal normally used to study non-ideal flow by stimulus response technique is ________ input?

Step

Both A. & B.

Pulse

Neither A. nor B.

29 / 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_________?

97.5

2.5

100

30 / 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 sec-1

0.03 min-1

31 / 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) ?

2-Jan

4-Jan

32 / 50

Sum of the powers of the concentration terms in the rate equation is called the ______ of the reaction?

Overall order

Molecularity

None of these

Order

33 / 50

The dimensions of rate constant for reaction 3A ? B are (l/gm mole)/min. Therefore the reaction order is________?

34 / 50

The dispersion number of perfect mixed flow is___________?

< 2100

> 150

35 / 50

Pick out the wrong statement?

Enzymes help in increasing the activation energy of the reaction

Catalytic activity of enzyme catalysed reactions which is affected by temperature, pH value & chemical agents, is maximum at a temperature of about 45?C

Equilibrium concentrations in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & products

Most of the enzyme catalysed reactions involve at least two substrates

36 / 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

0.5

0.875

Data insufficient to calculate

37 / 50

The catalyst in a second order reversible reaction increases the rate of the forward reaction_____?

And backward reaction equally

To a greater extent than that of the backward reaction

And decreases that of backward reaction

Only

38 / 50

Radioactive decay follows _______ order kinetics?

Zero

Third

Second

First

39 / 50

Reverse reaction in a chemical equilibrium is favoured by the_________?

Removal of one of the products regularly

Increase in the concentration of one of the reactants

Increase in the concentration of one of the products

None of these

40 / 50

Space time equals the mean residence time___________?

For narrow diameter tubular reactor

For large diameter tubular reactor

When the density of the reaction mixture is constant

For CSTR

41 / 50

Slurry reactors are characterised by the__________?

Lack of intraparticle diffusion resistance

Presence of two mobile phases

Both A. and B.

Neither A. nor B.

42 / 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

43 / 50

Sometimes, batch process is preferred over continuous process, when the product_____?

Neither A. nor B.

Sales demand is fluctuating

Quality & yield cannot be achieved in continuous processes, because of long residence time

Both A. & B.

44 / 50

Sulphuric acid is used as a catalyst in the________?

Hydrogenation of oils

Alkylation of hydrocarbons

None of these

Gas phase oxidation of SO2 in chamber process

45 / 50

Reaction of benzene with chlorine gas to produce tri-chlorobenzene exemplifies a/an _______ reaction?

Elementary

None of these

Parallel

Consecutive

46 / 50

Semibatch reactor is preferred, when a/an___________?

A gas is to be reacted with liquid (e.g. hydrogenation of fat)

All A., B., and C.

Undesirable side reaction (at high concentration of one of the reactants) is to be avoided

A highly exothermic reaction is to be controlled

47 / 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 ?

48 / 50

The eddy diffusivity for a liquid in plug flow must be__________?

Between 0 and 1

49 / 50

Pick out the wrong statement?

A particular chemical reaction is more temperature sensitive at low temperatures

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 very high value of equilibrium constant, K (K >> 1) indicates that the reaction is practically irreversible in nature

50 / 50

The catalyst in a first order chemical reaction changes the__________?

Heat of reaction

Equilibrium constant

Activation energy

Heat of formation of the product

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