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ChE Concepts > ChE Thermodynamics - INDIABIX > Flashcards

ChE Thermodynamics - INDIABIX Flashcards

1
Q

Maximum work that could be secured by expanding the gas over a given pressure range is the __________ work.

A

isothermal

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2
Q

Internal energy change of a system over one complete cycle in a cyclic process is

A

zero

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3
Q

Heating of water under atmospheric pressure is an __________ process.

A

isobaric

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4
Q

Van Laar equation deals with the activity coefficients in
(HINDI BA TO VDW??)

A

binary solutions

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5
Q

High __________ is an undesirable property for a good refrigerant.

A

viscosity

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6
Q

Solubility of a substance which dissolves with an increase in volume and liberation of heat will be favored by the

A

low pressure and low temperature

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7
Q

Entropy is a measure of the __________ of a system.

A

disorder

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8
Q

A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is

A

negative

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9
Q

Fundamental principle of refrigeration is based on the __________ law of thermodynamics.

A

second

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10
Q

For a spontaneous process, free energy

A

decreases whereas the entropy increases

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11
Q

A refrigeration cycle is a reversed heat engine. Which of the following has the maximum value of the co-efficient of performance (COP) for a given refrigeration effect ?

A

Carnot refrigeration cycle

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12
Q

In a working refrigerator, the value of COP is always

A

> 1

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13
Q

__________ increases with increase in pressure.

A. The melting point of wax
B. The boiling point of a liquid
C. both (a) and (b)
D. neither (a) nor (b

A

both (a) and (b)

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14
Q

A refrigerator may be termed as a

A

heat pump

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15
Q

For a stable phase at constant pressure and temperature, the fugacity of each component in a binary system __________ as its mole fraction increases.

A

increases

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16
Q

Which of the following is not an intensive property ?

A

heat capacity

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17
Q

Out of the following refrigeration cycles, which one has the minimum COP (Co-efficient of performance)?

A

air cycle

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18
Q

Measurement of thermodynamic property of temperature is facilitated by __________ law of thermodynamics.

A

zeroth

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19
Q

The theoretical minimum work required to separate one mole of a liquid mixture at 1 atm, containing 50 mole % each of n- heptane and n- octane into pure compounds each at 1 atm is

A

-RT ln 0.5

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20
Q

Keeping the pressure constant, to double the volume of a given mass of an ideal gas at 27°C, the temperature should be raised to __________ °C.

A

327

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21
Q

Entropy of an ideal gas depends upon its

A. pressure
B. temperature
C. both (a) & (b)
D. neither (a) nor (b)

A

both (a) & (b)

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22
Q

Isobaric process means a constant process.

A

pressure

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23
Q

No work is done by the system, when a reaction occurs at constant

A

volume

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24
Q

If the vapour pressure at two temperatures of a solid phase in equilibrium with its liquid phase are known, then the latent heat of fusion can be calculated by the

A

Clayperon-Claussius equation

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25
Q

The freezing point of a liquid decreases when the pressure is increased, if the liquid __________ while freezing.

A

Contracts

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26
Q

At the absolute zero temperature, the entropy of every perfectly crystalline substance becomes zero”. This follows from the

A

third law of thermodynamics

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27
Q

During Joule-Thompson expansion of gases

A

enthalpy remains constant.

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28
Q

The accentric factor of a materical, ‘ω’, is defined as ω = -log10(Prsat)Tr^-1 = 0.7, where, Pr^sat = reduced vapor pressure, Tr = reduced temperature. The value of accentric factor is always

A

< 1

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29
Q

Degrees of freedom at triple point will be

A

0

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30
Q

“Law of corresponding states” says that

A

two different gases behave similarly, if their reduced properties (i.e. P, V and T) are same.

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31
Q

Linde gas liquefaction process employs cooling

A

by throttling

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32
Q

Pick out the wrong statement pertaining to the decomposition of PCl5 represented by, PCl5 PCl3 + Cl2.Degree of dissociation of PCl5 will

A. decrease on addition of Cl2.
B. increase on addition of an inert gas at constant pressure.
C. decrease on increasing the pressure of the system.
D. none of these

A

none of these

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33
Q

Joule-Thomson experiment is

A. isobaric
B. adiabatic
C. isenthalpic
D. both(b) & (c)

A

both(b) & (c)

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34
Q

1st law of thermodynamics is nothing but the law of conservation of

A

energy

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35
Q

In a reversible chemical reaction (where, Δx = number of moles of products-number of moles of reactants )

A. addition of inert gas favours the forward reaction, when Δx is positive.
B. pressure has no effect on equilibrium, when Δn = 0.
C. addition of inert gas has no effect on the equilibrium constant at constant volume for any value of Δx (+ ve, - ve) or zero).
D. all ‘a’, ‘b’ & ‘c’.

A

all ‘a’, ‘b’ & ‘c’.

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36
Q

Out of the following refrigeration cycles, which one has maximum COP ?

A

Carnot cycle

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37
Q

Pick out the correct statement:

A. In an isothermal system, irreversible work is more than reversible work.
B. Under reversible conditions, the adiabatic work is less than isothermal work.
C. Heat, work, enthalpy and entropy are all ‘state functions’.
D. Matter and energy can not be exchanged with the surroundings in a closed system

A

Under reversible conditions, the adiabatic work is less than isothermal work.

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38
Q

In any spontaneous process,

A

both F and A decreases

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39
Q

Which of the following is a thermodynamic property of a system ?

A

Entropy

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40
Q

Equilibrium constant decreases as the temperature

A

increases, for an exothermic reaction.

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41
Q

All gases during throttling process at atmospheric temperature and pressure show a cooling effect except

A

H2

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42
Q

Compressibility factor for almost all the gases are approximately same at the same

A

reduced pressure and reduced temperature.

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43
Q

Pick out the wrong statement.

A. Activity co-efficient is dimensionless.
B. In case of an ideal gas, the fugacity is equal to its pressure.
C. In a mixture of ideal gases, the fugacity of a component is equal to the partial pressure of the component.
D. The fugacity co-efficient is zero for an ideal gas.

A

The fugacity co-efficient is zero for an ideal gas.

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44
Q

Pick out the correct statement.

A. Compression ratio of an Otto engine is comparatively higher than a diesel engine.
B. Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio.
C. Otto engine efficiency decreases with the rise in compression ratio, due to decrease in work produced per quantity of heat.
D. Diesel engine normally operates at lower compression ratio than an Otto engine for an equal output of work.

A

Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio.

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45
Q

When pressure is applied on the system, ice water, then

A

more water will be formed.

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46
Q

Partial molar free energy of an element A in solution is same as its

A

chemical potential

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47
Q

Free energy change at equilibrium is

A

zero

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48
Q

Heat pump

A. accomplishes only space heating in winter.
B. accomplishes only space cooling in summer.
C. accomplishes both (a) and (b).
D. works on Carnot cycle.

A

accomplishes both (a) and (b).

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49
Q

The temperature at which both liquid and gas phases are identical, is called the __________ point.

A

critical

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50
Q

What is the value of ln y (where y = activity co-efficient) for ideal gases ?

A

Zero

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51
Q

A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system

A

U and S both decreases

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52
Q

Which is not a refrigerant ?

A. SO2
B. NH3
C. CCl2F2
D. C2H4Cl2

A

C2H4Cl2

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53
Q

The partial pressure of each constituent present in an alloy is __________ the total vapor pressure exerted by the alloy.

A

less than

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54
Q

Heat is added at constant pressure in an ideal __________ cycle.

A. Stirling
B. Brayton
C. Rankine
D. both (b) and (c)

A

both (b) and (c)

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55
Q

Entropy change of mixing two liquid substances depends upon the

A. molar concentration
B. quantity (i.e. number of moles)
C. both (a) and (b)
D. neither (a) nor (b)

A

both (a) and (b)

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56
Q

The four properties of a system viz. P, V, T, S are related by __________ equation.

A

Maxwell’s

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57
Q

If the pressure on 100 c.c. of air is halved, then its volume (at the same temperature) would be __________ c.c.

A

200

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58
Q

Pick out the wrong statement.

A. Cp of monoatomic gases such as metallic vapor is about 5 kcal/kg.atom.
B. The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state.
C. There is an increase in entropy, when a spontaneous change occurs in an isolated system.
D. At absolute zero temperature, the heat capacity for many pure crystalline substances is zero.

A

The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state.

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59
Q

The principle applied in liquefaction of gases is

A. adiabatic expansion.
B. Joule-Thomson effect.
C. both (a) and (b).
D. neither (a) nor (b).

A

both (a) and (b)

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60
Q

The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are

A

one

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61
Q

Any substance above its critical temperature exists as

A

gas

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62
Q

Which of the following decreases with increase in pressure ?

A. Melting point of ice
B. Melting point of wax
C. Boiling point of liquids
D. none of these

A

Melting point of ice

63
Q

Isentropic process means a constant __________ process.

A

entropy

64
Q

In case of steady flow compression polytropic process (PVn = constant), the work done on air is the lowest, when

A

n = 1

65
Q

A liquid under pressure greater than its vapour pressure for the temperature involved is called a __________ liquid.

A

subcooled

66
Q

For a real gas, the chemical potential is given by

A

RT dlnf

67
Q

At absolute zero temperature, all substances have the same

A

heat capacity

68
Q

Lowering of condenser temperature (keeping the evaporator temperature constant) in case of vapour compression refrigeration system results in

A

increased COP

69
Q

Pick out the correct statement.

A. If an insoluble gas is passed through a volatile liquid placed in a perfectly insulated container, the temperature of the liquid will increase.
B. A process is irreversible as long as Δ S for the system is greater than zero.
C. The mechanical work done by a system is always equal to P.dV.
D. The heat of formation of a compound is defined as the heat of reaction leading to the formation of the compound from its reactants.

A

The heat of formation of a compound is defined as the heat of reaction leading to the formation of the compound from its reactants.

70
Q

Grams of butane (C4H10) formed by the liquefaction of 448 litres of the gas (measured at (STP) would be

A

1160

71
Q

The thermodynamic law, PV^y = constant, is not applicable in case of
ideal compression of air.

A

free expansion of an ideal gas.

72
Q

Mollier diagram is a plot of

A

entropy vs. enthalpy

73
Q

The activity of an ideal gas is numerically __________ its pressure.

A

equal to

74
Q

When a gas in a vessel expands, its internal energy decreases. The process involved is

A

reversible

75
Q

A system is said to be isopiestic, if there is no __________ change.

A

pressure

76
Q

In a turbine, the fluid expands almost

A

adiabatically

77
Q

The unity of Planck’s constant ‘h’ in the equation, E = hv is

A

J-s
(joule-seconds)

78
Q

Specific/molar Gibbs free energy for a pure substance does not change during

A. sublimation
B. vaporisation
C. melting
D. either (a), (b) or (c)

A

either (a), (b) or (c)

79
Q

Refrigeration capacity of a household refrigerator may be round about __________ tons.

A

0.15

80
Q

Chemical potential is a/an

A. extensive property.
B. intensive property.
C. force which drives the chemical system to equilibrium.
D. both (b) and (c)

A

both (b) and (c)

81
Q

In polytropic process (PV^n = constant), if n = 1; it means a/an __________ process.

A

isothermal

82
Q

The melting point of paraffin wax (which contracts on solidification) __________ with pressure rise.

A

increases

83
Q

Co-efficient of Performance (COP) of a refrigerator is the ratio of the

A

refrigeration obtained to the work required.

84
Q

A solid metallic block weighing 5 kg has an initial temperature of 500°C. 40 kg of water initially at 25°C is contained in a perfectly insulated tank. The metallic block is brought into contact with water. Both of them come to equilibrium. Specific heat of block material is 0.4 kJ.kg-1. K-1. Ignoring the effect of expansion and contraction and also the heat capacity to tank, the total entropy change in kJ.kg-1 , K-1 is

A

0

85
Q

dW and dq are not the exact differential, because q and Ware
state functions

A

path functions

86
Q

Trouton’s ratio of __________ liquids is calculated using Kistiakowsky equation.

A. polar
B. non-polar
C. both (a) & (b)
D. neither (a) nor (b)

A

non-polar

87
Q

Activity co-efficient is a measure of the

A

departure from ideal solution behaviour.

88
Q

While dissolving a gas into a liquid at a constant temperature, the ratio of the concentration of the gas in the solution phase and in the gaseous phase is

A

constant

89
Q

Which of the following units is not present in both the vapor compression refrigeration system and absorption refrigeration system ?

A. Expansion valve
B. Condenser
C. Refrigerator
D. Compressor

A

Compressor

90
Q

For an isothermal reversible compression of an ideal gas

A

ΔE = ΔH = 0

91
Q

Melting of ice exemplifies a/an

A

endothermic reaction

92
Q

A refrigeration cycle is the same as a __________ cycle,

A

reversed heat engine

93
Q

At __________ point, all the three phases (i.e. solid, liquid and gas) co-exist.

A

triple

94
Q

Kopp’s rule is used to calculate the heat capacity of

A

solids

95
Q

__________ explains the equilibrium constant for any chemical reaction.

A

Law of mass action

96
Q

Which of the following is not a reversible process ?

A. Expansion of an ideal gas against constant pressure.
B. Atmospheric pressure vaporisation of water at 100°C.
C. Solution of NaCl in water at 50°C.
D. None of these.

A

Solution of NaCl in water at 50°C.

97
Q

Pick out the wrong statement.

A. A closed system does not permit exchange of mass with its surroundings but may permit exchange of energy.
B. An open system permits exchange of both mass and energy with its surroundings.
C. The term microstate is used to characterize an individual, whereas macro-state is used to designate a group of micro-states with common characteristics.
D. none of the above.

A

none of the above

98
Q

Which of the following exemplifies an adiabatic process ?

A. Melting of ice.
B. Condensation of alcohol vapor.
C. Sudden bursting of a cycle tube.
D. Evaporation of water.

A

Sudden bursting of a cycle tube.

99
Q

Entropy, which is a measure of the disorder of a system is

A

zero at absolute zero temperature for a perfect crystalline substance

100
Q

Critical temperature is defined as the temperature above which a gas will

A

never liquify however high the pressure may be

101
Q

The standard Gibbs free energy change of a reaction depends on the equilibrium

A

temperature

102
Q

Gibbs-Duhem equation relates composition in liquid phase and the __________ at constant temperature & pressure.

A. fugacity
B. partial pressure
C. activity co-efficient
D. (a), (b), and (c)

A

(a), (b), and (c)

103
Q

In an ideal solution, the activity of a component equals its

A

mole fraction

104
Q

A gas has a volume of 27.3 c.c. at 0°C. Its volume at 10°C (if pressure remains unchanged) will be __________ c.c.

A

28.3

105
Q

Clapeyron equation deals with the

A

rate of change of vapour pressure with temperature.

106
Q

Which of the following is an undesirable characteristics of a refrigerant ?

A. It should be non-explosive.
B. It should have a sub-atmospheric vapor pressure at the temperature in refrigerator coils.
C. Its vapor pressure at the condenser temperature should be very high.
D. None of these.

A

None of these.

107
Q

“The rate at which a substance reacts is proportional to its active mass and the rate of a chemical reaction is proportional to the product of active masses of the reacting substances”. This is the

A. Lewis-Randall rule.
B. statement of Vant-Hoff equation.
C. Le-Chatelier’s principle.
D. none of these.

A

none of these

108
Q

What is the ratio of adiabatic compressibility to isothermal compressibility ?

A

< 1

109
Q

The absolute entropy for all crystalline substances at absolute zero temperature is

A

zero

110
Q

Pick out the wrong statement.

A. Phase rule variables are intensive properties.
B. Heat and work are both state function.
C. The work done by expansion of a gas in vacuum is zero.
D. Cp and Cv are state function.

A

Heat and work are both state function

111
Q

Compressibility factor of a gas is

A

unity, if it follows PV = nRT.

112
Q

Which of the following is not an extensive property ?

A. Free energy
B. Entropy
C. Refractive index
D. None of these

A

Refractive index

113
Q

Forward reaction will be favoured for the exothermic reaction, represented by CO + H2O CO2 + H2, by

A

low temperature and high pressure.

114
Q

Enthalpy of a gas depends upon its

A

temperature

115
Q

When dilute aqueous solutions of two salts are mixed, the process is associated with

A

increase in temperature

116
Q

Pick out the correct statement.

A. Like internal energy and enthalpy, the absolute value of standard entropy for elementary substances is zero.
B. Melting of ice involves increase in enthalpy and a decrease in randomness.
C. The internal energy of an ideal gas depends only on its pressure.
D. Maximum work is done under reversible conditions.

A

Maximum work is done under reversible conditions.

117
Q

Chemical engineering thermodynamics is concerned with the __________ in/of chemical processes.

A

energy transformation from one form to the another

118
Q

An isolated system can exchange __________ with its surroundings.

A

neither matter nor energy

119
Q

Requisites of a reversible process is that the

A

friction in the system should be absent.

120
Q

Fugacity is most helpful in

A

representing actual behaviour of real gases.

121
Q

The energy of activation of exothermic reaction is

A

not possible to predict

122
Q

In the reaction; N2 + O2 -> 2NO, increasing the pressure will result in

A

no change in equilibrium condition

123
Q

A cyclic engine exchanges heat with two reservoirs maintained at 100 and 300°C respectively. The maximum work (in J) that can be obtained from 1000 J of heat extracted from the hot reservoir is

A

349

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ChE Concepts (2 decks)

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