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Let me cook > ChE Thermodynamics > Flashcards

ChE Thermodynamics Flashcards

1
Q

Maximum work that could be secured by expanding the gas over a given pressure range is the __________ work.
A. Isothermal
B. Adiabatic
C. Isentropic
D. None of these

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 co-efficients in
A. Binary Solutions
B. Ternary Solutions
C. Azeotropic Mixtures
D. None of these

A

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 favoured by the
_______ pressure and _______ temperature.

A

low, low

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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 (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. Vapor compression cycle using expansion valve.
B. Air refrigeration cycle.
C. Vapor compression cycle using expansion engine.
D. Carnot refrigeration cycle.

A

D. Carnot refrigeration cycle.

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12
Q

In a working refrigerator, the value of COP is always

A

greater than 1

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13
Q

__________ increases with increase in pressure.
A. Melting point of a wax
B. Boiling point of a liquid
C. Both a and b
D. None of these

A

C. 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. Chemical potential
B. Surface tension
C. Heat capacity
D. None of these

A

C. Heat capacity

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17
Q

Out of the following refrigration cycles, which one has the minimum COP (Co-efficient of performance)?
A. Air cycle
B. Carnot Cycle
C. Ordinary vapour compression cycle
D. Vapour compression with a reversible expansion engine

A

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

Entropy of an ideal gas depends upon its
A. Pressure
B. Temperature
C. Both a and b
D. None of these

A

C. Both a and b

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20
Q

Isobaric process means a constant ________ process.

A

Pressure

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21
Q

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

A

Volume

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22
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

Clausius-Clapeyron Equation

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23
Q

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

A

Contracts

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24
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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25
Q

During Joule-Thomson expansion of gases, ________ remains constant

A

Enthalpy

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26
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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27
Q

Linde gas liquefaction process employs cooling

A

by throttling

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28
Q

Joule-Thomson experiment is
A. isobaric
B. Adiabatic
C. Isenthalpic
D. Both b and c

A

D. Both b and c

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29
Q

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

A

Energy

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30
Q

Out of the following refrigeration cycles, which one has maximum COP ?
A. Air cycle
B. Carnot Cycle
C. Ordinary vapour compression cycle
D. Vapour compression with a reversible expansion engine

A

B. Carnot Cycle

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31
Q

Which of the following is a thermodynamic property of a system ?
A. Concentration
B. Mass
C. Temperature
D. Entropy

A

D. Entropy

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32
Q

Equilibrium constant decreases as the temperature _____

A

increases, for an exothermic reaction

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33
Q

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

A

Hydrogen gas

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34
Q

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

A

reduced pressure and reduced temperature.

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35
Q

In jet refrigerators, the refrigerating fluid is practically always

A

water

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36
Q

Water on heating from 1 to 4°C

A

contracts

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37
Q

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

A

more water will be formed.

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38
Q

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

A

chemical potential

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39
Q

Free energy change at equilibrium is

A

zero

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40
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

c. accomplishes both (a) and (b).

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41
Q

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

A

Critical Point

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42
Q

A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system, U _________ and S __________

A

decreases, decreases

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43
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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44
Q

Heat is added at constant pressure in an ideal __________ cycle.
A. Stirling
B. Brayton
C. Rankine
D. both (b) and (c)

A

D. both (b) and (c)

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45
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

C. both (a) and (b)

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46
Q

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

A

Maxwell’s Equation

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47
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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48
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

C. both (a) and (b).

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49
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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50
Q

Any substance above its critical temperature exists as

A

gas

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51
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

A. Melting point of ice

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52
Q

Isentropic process means a constant __________ process.

A

Entropy

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53
Q

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

A

n=1

54
Q

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

A

subcooled

55
Q

For a real gas, the chemical potential is given by

A

RT dlnf

56
Q

At absolute zero temperature, all substances have the same

A

heat capacity

57
Q

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

A

increased

58
Q

he thermodynamic law, PV^n = constant, is not applicable in case of
A. ideal compression of air.
B. free expansion of an ideal gas.
C. adiabatic expansion of steam in a turbine.
D. adiabatic compression of a perfect gas.

A

B. free expansion of an ideal gas.

59
Q

Mollier diagram is a plot of

A

Entropy vs Enthalpy

60
Q

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

A

equal to

61
Q

Specific heat of a gas for a reversible adiabatic process is

A

zero

62
Q

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

A

reversible

63
Q

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

A

pressure

64
Q

In a turbine, the fluid expands almost

A

adiabatically

65
Q

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

A

J-s

66
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

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

67
Q

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

A

0.15

68
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

D. both (b) and (c)

69
Q

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

A

Isothermal

70
Q

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

A

increases

71
Q

Co-efficient of Performance (COP) of a refrigerator is the ratio of the
A. work required to refrigeration obtained.
B. refrigeration obtained to the work required.
C. lower to higher temperature.
D. higher to lower temperature.

A

B. refrigeration obtained to the work required.

72
Q

dW and dq are not the exact differential, because q and W are

A

path functions

73
Q

Activity co-efficient is a measure of the
A. departure from ideal solution behaviour.
B. departure of gas phase from idea] gas law.
C. vapour pressure of liquid.
D. none of these.

A

A. departure from ideal solution behaviour.

74
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

75
Q

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

A

Compressor

76
Q

Melting of ice exemplifies a/an ________ reaction

A

endothermic

77
Q

A refrigeration cycle is the same as a __________ cycle,

A

reversed heat engine

78
Q

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

A

triple

79
Q

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

A

solids

80
Q

__________ explains the equilibrium constant for any chemical reaction.

A

Law of mass action

81
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

C. Sudden bursting of a cycle tube.

82
Q

Entropy, which is a measure of the disorder of a system is
A. independent of pressure.
B. independent of temperature.
C. zero at absolute zero temperature for a perfect crystalline substance.
D. all (a), (b) & (c)

A

C. zero at absolute zero temperature for a perfect crystalline substance.

83
Q

Critical temperature is defined as the temperature above which a gas will
A. not liquify (barring exceptions).
B. immediately liquify.
C. never liquify however high the pressure may be.
D. none of these.

A

C. never liquify however high the pressure may be.

84
Q

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

A

temperature

85
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

D. (a), (b), and (c)

86
Q

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

A

mole fraction

87
Q

Clayperon equation deals with the
A. rate of change of vapour pressure with temperature.
B. effect of an inert gas on vapour pressure.
C. calculation of ΔF for spontaneous phase change.
D. temperature dependence of heat of phase transition.

A

A. rate of change of vapour pressure with temperature.

88
Q

What is the ratio of adiabatic compressibility to isothermal compressibility ?

A

less than 1

89
Q

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

A

zero

90
Q

Which of the following is not an extensive property ?
A. Free energy
B. Entropy
C. Refractive index
D. None of these

A

C. Refractive index

91
Q

Enthalpy of a gas depends upon its

A

temperature

92
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

D. Maximum work is done under reversible conditions

93
Q

Chemical engineering thermodynamics is concerned with the __________ in/of chemical processes.
A. reaction mechanism
B. calculation of rates
C. energy transformation from one form to the another
D. none of these

A

C. energy transformation from one form to the another

94
Q

An isolated system can exchange __________ with its surroundings.

A

neither matter nor energy

95
Q

Requisites of a reversible process is that the
A. system and surroundings pressure be equal.
B. friction in the system should be absent.
C. system and surroundings temperature be equal.
D. none of these.

A

B. friction in the system should be absent.

96
Q

Fugacity is most helpful in
A. representing actual behaviour of real gases.
B. representing actual behaviour of ideal gases.
C. the study of chemical equilibria involving gases at atmospheric pressure.
D. none of these

A

A. representing actual behaviour of real gases.

97
Q

When a gas is subjected to adiabatic expansion, it gets cooled due to

A

energy spent in doing work.

98
Q

Joule-Thomson effect i.e., a throttling process is a constant __________ process.

A

enthalpy

99
Q

In the equation, PV^n = Constant, if the value of n = 0, then it represents a reversible __________ process.

A

isobaric

100
Q

Work done in an adiabatic process between two states depends on the
A. rate of heat transmission
B. initial state only
C. end states only
D. none of these

A

C. end states only

101
Q

The number of degree of freedom for an azeotropic mixture of ethanol and water in vapour-liquid equilibrium, is

A

1

102
Q

The internal energy of an ideal gas is a function of its __________ only.

A

temperature

103
Q

At constant temperature and pressure, for one mole of a pure substance, the ratio of the free energy to the chemical potential is

A

one

104
Q

The change in __________ is equal to the reversible work for compression in steady state flow process under isothermal condition.

A

Gibbs free energy

105
Q

Work done is a ______ function

A

path

106
Q

Entropy of the system decreases, when
A. snow melts into water.
B. a gas expands spontaneously from high pressure to low pressure.
C. water is converted into ice.
D. both (b) & (c).

A

D. both (b) & (c).

107
Q

Extensive properties of a thermodynamic system depend upon the __________ of the system

A

mass

108
Q

If an ideal solution is formed by mixing two pure liquids in any proportion, then the __________ of mixing is zero.
A. enthalpy
B. volume
C. both ‘a’ & ‘b’
D. neither ‘a’ nor ‘b’

A

C. both ‘a’ & ‘b’

109
Q

Near their critical temperatures, all gases occupy volumes __________ that of the ideal gas.

A

less than

110
Q

The fugacity co-efficient of a gas at constant pressure ____with the increase of reduced temperature.

A

increases

111
Q

The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called the __________ temperature.

A

Boyle

112
Q

If the molar heat capacities (Cp or Cv) of the reactants and products of a chemical reaction are identical, then, with the increase in temperature, the heat of reaction will

A

remain unaltered

113
Q

Equation which relates pressure, volume and temperature of a gas is called the

A

equation of state

114
Q

For a single component two phase mixture, the number of independent variable properties are

A

1

115
Q

__________ law of thermodynamics ascertains the direction of a particular spontaneous process.

A

Second

116
Q

At normal boiling point, molar entropy of vaporisation is __________ Joule/K°.mole.

A

92

117
Q

For an ideal solution, the value of activity co-efficient is

A

1

118
Q

The expression, nCv(T2 - T1), is for the __________ of an ideal gas.
A. work done under adiabatic condition
B. co-efficient of thermal expansion
C. compressibility
D. none of these

A

A. work done under adiabatic condition

119
Q

The number of degrees of freedom at the triple point of water is

A

0

120
Q

Which of the following is a widely used refrigerant in vapour compression refrigeration system (using large centrifugal compressor)?
A. Freon
B. Liquid sulphur dioxide
C. Methyl chloride
D. Ammonia

A

A. Freon

121
Q

Internal energy is equal to the heat absorbed in case of a/an __________ process.

A

Constant volume

122
Q

The first law of thermodynamics is a restatement of the law of conservation of

A

energy

123
Q

Joule-Thomson co-efficient for a perfect gas is

A

0

124
Q

In an adiabatic process, the ________ is zero

A

heat transfer (Q)

125
Q

A nozzle is a device, which _______ kinetic energy, _________ pressure

A

increases, decreases

126
Q

During the phase transition, __________ changes.

A

volume

127
Q

The work done in an adiabatic change in a particular gas depends upon changes in the __________ only.

A

temperature

128
Q

In an isothermal process on an ideal gas, the pressure increases by 0.5 percent. The volume decreases by about __________ percent.

A

0.5

129
Q

Partial molal quantities are important in the study of
A. ideal gases
B. ideal solutions
C. non-ideal mixtures
D. a pure component

A

C. non-ideal mixtures

130
Q

Number of degrees of freedom for a three phase system in equilibrium comprising of three non-reacting chemical species is

A

2

131
Q

__________ functions are exemplified by heat and work.

A

Path

132
Q

What is the number of degree of freedom for a system of two miscible non-reacting species in vapor-liquid equilibrium forming an azeotrope ?

A

1

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