Indiabix - Thermodynamics Flashcards
1
Q
Maximum work that could be secured by expanding the gas over a given pressure range is the __________ work.
A
isothermal
2
Q
Internal energy change of a system over one complete cycle in a cyclic process is
A
zero
3
Q
Van Laar equation deals with the activity co-efficients in
A
binary solutions
4
Q
Entropy is a measure of the __________ of a system.
A
disorder
5
Q
A refrigerator may be termed as a
A
heat pump
6
Q
Out of the following refrigration cycles, which one has the minimum COP (Co-efficient of performance)?
A
Air cycle
7
Q
No work is done by the system, when a reaction occurs at constant
A
volume
8
Q
The freezing point of a liquid decreases when the pressure is increased, if the liquid __________ while freezing.
A
contracts
9
Q
“At the absolute zero temperature, the entropy of every perfectly crystalline substance becomes zero”. This follows from the
A
third law of thermodynamics
10
Q
During Joule-Thomson expansion of gases
A
enthalpy remains constant.
11
Q
Degress of freedom at triple point will be
A
0
12
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.
13
Q
Linde gas liquefaction process employs cooling
A
by throttling
14
Q
Equilibrium constant decreases as the temperature
A
increases, for an exothermic reaction.
15
Q
The expression, (1) , gives the free energy change
A
with pressure changes at constant temperature.
16
Q
In jet refrigerators, the refrigerating fluid is practically always
A
water
17
Q
Water on heating from 1 to 4°C
A
contracts
18
Q
Partial molar free energy of an element A in solution is same as its
A
chemical potential
19
Q
Free energy change at equilibrium is
A
zero
20
Q
The temperature at which both liquid and gas phases are identical, is called the __________ point.
A
critical
21
Q
What is the value of ln y (where y = activity co-efficient) for ideal gases ?
A
Zero
22
Q
The partial pressure of each constituent present in an alloy is __________ the total vapor pressure exerted by the alloy.
A
less than
23
Q
Which of the following decreases with increase in pressure ?
A
Melting point of ice
24
Q
A liquid under pressure greater than its vapour pressure for the temperature involved is called a __________ liquid.
A
subcooled
25
At absolute zero temperature, all substances have the same
heat capacity
26
Lowering of condenser temperature (keeping the evaporator temperature constant) in case of vapour compression refrigeration system results in
increased COP.
27
When a gas in a vessel expands, its internal energy decreases. The process involved is
reversible
28
Refrigeration capacity of a household refrigerator may be round about __________ tons.
0.15
29
The melting point of paraffin wax (which contracts on solidification) __________ with pressure rise.
increases
30
Activity co-efficient is a measure of the
departure from ideal solution behaviour.
31
Kopp's rule is used to calculate the heat capacity of
solids
32
In an ideal solution, the activity of a component equals its
mole fraction.
33
Clayperon equation deals with the
rate of change of vapour pressure with temperature.
34
The absolute entropy for all crystalline substances at absolute zero temperature is
zero
35
Forward reaction will be favoured for the exothermic reaction, represented by CO + H2O ⇌ CO2 + H2, by
low temperature and high pressure.
36
Enthalpy of a gas depends upon its
temperature
37
Fugacity is most helpful in
representing actual behaviour of real gases.
38
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
349
39
In the equation, PV^n = Constant, if the value of n = 0, then it represents a reversible __________ process.
isobaric
40
Near their critical temperatures, all gases occupy volumes __________ that of the ideal gas.
less than
41
What is the number of degrees of freedom for liquid water in equilibrium with a mixture of nitrogen and water vapor ?
2
42
All gases above its inversion temperature, in a throttling process will show
a heating effect.
43
First law of thermodynamics is mathematically stated as
dQ = dE + dW
44
Translational kinetic energy of molecules of an ideal gas is proportional to (where, T = absolute temperature of the gas )
T
45
Equation which relates pressure, volume and temperature of a gas is called the
equation of state
46
The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called __________ temperature.
Boyle
47
The expression, nCv(T2 - T1), is for the __________ of an ideal gas.
work done under adiabatic condition
48
Which of the following is a widely used refrigerant in vapour compression refrigeration system (using large centrifugal compressor)?
Freon
49
Internal energy is equal to the heat absorbed in case of a/an __________ process.
constant volume
50
The first law of thermodynamics is a restatement of the law of conservation of
mass
51
In an adiabatic process, the
heat transfer is zero.
52
A nozzle is a device, which
increases kinetic energy and decreases pressure.
53
The work done in an adiabatic change in a particular gas depends upon changes in the __________ only.
temperature
54
Number of degrees of freedom for a three phase system in equilibrium comprising of three non-reacting chemical species is
2
55
Critical solution temperature (or the con-solute temperature) for partially miscible liquids (e.g., phenol-water) is the minimum temperature at which
a homogeneous solution (say of phenol water) is formed.
56
__________ functions are exemplified by heat and work.
Path
57
The entropy change in a reversible isothermal process, when an ideal gas expands to four times its initial volume is
R loge 4
58
Pick out the wrong statement.
A refriferation cycle violates the second law of thermadynamics.
59
The equation, PV = nRT, is best obeyed by gases at
low pressure & high temperature.
60
Internal energy of an element at 1 atm and 25° C is __________ kcal/kg.mole.
0
61
Which of the following liquid metals has the highest thermal conductivity ?
Molten sodium
62
Which of the following has the least thermal efficiency ?
Steam engine
63
Number of components (C), phase (P) and degrees of freedom (F) are related by Gibbs phase rule as
P + F - C = 2
64
The value of Cp & Cv respectively for monoatomic gases in Kcal/kg Mole . °K are
5 & 3
65
During a reversible isothermal expansion of an ideal gas, the entropy change is
+ve
66
Those solutions in which there is no volume change upon mixing the components in the liquid state and which, when diluted do not undergo any heat change (i.e. heat of dilution is zero), are called __________ solutions.
ideal
67
The compressibility factor of a gas is given by (where, V1 = actual volume of the gas V2 = gas volume predicted by ideal gas law )
V1/V2
68
"If different processes are used to bring about the same chemical reaction, the enthalpy change is same for all of them". This is __________ law.
Hess's
69
Fugacity is a measure of the
escaping tendencies of the same substance in different phases of a system.
70
The quantitative effect of temperature on chemical equilibrium is given by the
Vant-Hoff equation.
71
For an irreversible process involving only pressure-volume work
(dF)T, p <0
72
The enthalpy change when ammonia gas is dissolved in water is called the heat of
solution
73
Critical compressibility factor for all substances
are more or less constant (vary from 0.2 to 0.3).
74
For a given substance at a specified temperature, activity is __________ to fugacity.
directly proportional
75
In case of vapour compression refrigeration system, elevating the evaporator temperature (keeping the condenser temperature constant) results in
enhanced COP.
76
As the temperature is lowered towards the absolute zero, the value of the quantity approaches
zero
77
In case of a reversible process (following pv^n = constant), work obtained for trebling the volume (v1 = 1 m^3 and v2 3 m^3 ) is max imum, when the value of 'n' is
0
78
The Carnot co-efficient of performance (COP) of a domestic air conditioner compared to a household refrigerator is
less
79
The unit of fugacity is the same as that of the
pressure
80
The total change in the enthalpy of a system is independent of the
number of intermediate chemical reactions involved.
81
Vapour which is at a pressure smaller than the saturation pressure for the temperature involved is called a __________ vapour.
superheated
82
At equilibrium condition, the chemical potential of a material in different phases in contact with each other is equal. The chemical potential for a real gas (μ) is given by(where, μ = standard chemical potential at unit fugacity (f° = 1 atm.) and the gas behaves ideally.)
μ° + RT ln f
83
Which of the following is not an intensive property ?
Volume
84
With increase in pressure (above atmospheric pressure), the Cp of a gas
increases
85
A change in state involving a decrease in entropy can be spontaneous, only if
it is exothermic.
86
Joule-Thomson co-efficient which is defined as, (1) , changes sign at a temperature known as inversion temperature. The value of Joule-Thomson co-efficient at inversion temperature is
0
87
Heat is added at constant temperature in an ideal __________ cycle.
Stirling
88
Pick out the correct equation relating 'F' and 'A'.
F = A + PV
89
In a reversible process
Tds = dE + dW
90
With increase in compression ratio, the efficiency of the otto engine
increases
91
Refrigerants commonly used for domestic refrigerators are
ethyl chloride or methyle chloride
92
Heat of formation of an element in its standard state is
0
93
The shape of T-S diagram for Carnot Cycle is a
rectangle
94
In the equation, PVn = constant, if the value of n = 1, then it represents a reversible __________ process.
isothermal
95
Which of the following non-flow reversible compression processes require maximum work ?
Adiabatic process
96
"When a system in equilibrium is subjected to a change in temperature, pressure or concentration, the equilibrium is displaced in a direction which tends to undo the effect of the change." This is called the
Le-Chatelier principle.
97
Sound waves propagation in air exemplifies an __________ process.
adiabatic
98
For equilibrium process (i.e. reversible) in an isolated system
ds = 0
99
With increase in reduced temperature, the fugacity co-efficient of a gas at constant reduced pressure
increases
100
Efficiency of a heat engine working on Carnot cycle between two temperature levels depends upon the
two temperatures only.
101
In Joule-Thomson porous plug experiment, the
enthalpy does not remain constant.
102
A Carnot cycle consists of the following steps :
Two isothermals and two isentropics.
103
For a cyclic process, a fixed ratio between heat and work
always exists
104
In vapour compression refrigeration system, if the evaporator temperature and the condenser temperatures are -13°C and 37°C respetively, the Carnot COP will be
5.2
105
Which of the following is an extensive property of a system ?
Heat capacity
106
The reaction A (l) → R(g) is allowed to reach equilibrium conditions in an autoclave. At equilibrium, there are two phases, one a pure liquid phase of A and the other a vapor phase of A, R and S. Initially A alone is present. The number of degrees of freedom are
1
107
Cp - Cv = R is valid for __________ gases.
ideal
108
Melting of wax is accompanied with __________ in entropy.
increase
109
Tea kept in a thermos flask is vigorously shaken. If the tea is considered as a system, then its temperature will
increase
110
After throttling, gas temperature
decreases
111
When liquid and vapour phase of multi-component system are in equilibrium (at a given temperature and pressure), then chemical potential of each component is
same in both the phases.
112
On opening the door of an operating refrigerator kept in a closed room, the temperature of the room will
increase
113
Gibbs-Duhem equation
states that n1dμ1 + n2dμ2 + ....njdμj = 0, for a system of definite composition at constant temperature and pressure.
114
The internal energy of an ideal gas does not change in a reversible __________ process.
isothermal
115
For an ideal gas, the chemical potential is given by
RT dlnP
116
Two substances are in equilibrium in a reversible chemical reaction. If the concentration of each substance is doubled, then the value of the equilibrium constant will be
same
117
Heat requirement for decomposition of a compound into its elements is __________ that is evolved during the formation of that compound from its elements.
the same
118
Which of the following equations is obtained on combining 1st and 2nd law of thermodynamics, for a system of constant mass?
dE = Tds - PdV
119
The efficiency of a Carnot heat engine operating between absolute temperatures T1 and T2 (when, T1 > T2) is given by (T1 - T2)/T1. The co-efficient of performance (C.O.P.) of a Carnot heat pump operating between T1 and T2 is given by
T1/(T1-T2)
120
Throttling (Joule-Thomson effect) process is a constant __________ process.
enthalpy
121
Boiling of liquid is accompanied with increase in the
vapor pressure.
122
Change of state namely evaportation condensation, freezing and melting is an __________ process.
isothermal
123
With increase in temperature, the internal energy of a substance
increases
124
It is desired to bring about a certain change in the state of a system by performing work on the system under adiabatic conditions.
The amount of work needed is path dependent.
125
For organic compounds, group contribution method can be used for the estimation of
critical properties.
126
What happens in a reversible adiabatic compression ?
Heating occurs
127
The efficiency of an Otto engine compared to that of a diesel engine, for the same compression ratio will be
more
128
Isotherm on an enthalpy-concentration diagram, for an ideal solution will be a
straight line
129
A cylinder contains 640 gm of liquid oxygen. The volume occupied (in litres) by the oxygen, when it is released and brought to standard conditions (0°C, 760 mm Hg) will be __________ litres.
448
130
Dryness fraction of wet steam is defined as the ratio of mass of vapour in the mixture to the mass of mixture __________ calorimeter is not used for measuring the dryness fraction of steam.
Bomb
131
As the time is passing, entropy of the universe
is increasing
132
Which of the following processes can not be made reversible even under ideal condition of operation?
Free expansion of a gas.
133
The relation connecting the fugacities of various components in a solution with one another and to composition at constant temperature and pressure is called the __________ equation.
Gibbs-Duhem
134
With increase in temperature, the atomic heat capacities of all solid elements
increases
135
The temperature at the eutectic point of the system is the __________ temperature that can be attained in the system.
lowest
136
Steam undergoes isentropic expansion in a turbine from 5000 kPa and 400°C (entropy = 6.65 kJ/kg K) to 150 kPa) (entropy of saturated liquid = 1.4336 kJ/kg . K, entropy of saturated vapour = 7.2234 kJ/kg. K) The exit condition of steam is
superheated vapour.
137
An isentropic process is carried out at constant
volume
138
The necessary condition for phase equilibrium in a multiphase system of N components is that the
chemical potentials of a given component should be equal in all phases.
139
Compressibility factor-reduced pressure plot on reduced co-ordinates facilitates
use of only one graph for all gases.
140
Pick out the wrong statement.
At constant pressure, solubility of a gas in a liquid diminishes with rise in temperature.
141
Reduced pressure of a gas is the ratio of its
pressure to critical pressure.
142
Air enters an adiabatic compressor at 300K. The exit temperature for a compression ratio of 3, assuming air to be an ideal gas (Y = Cp/Cv = 7/5) and the process to be reversible, is
300(32/7)
143
An ideal monoatomic gas is taken round the cycle ABCDA as shown below in the P-V diagram (1) The work done during the cycle is
PV
144
Third law of thermodynamics is concerned with the
value of absolute entropy.
145
Claude's liquefaction process employs the cooling of gases by
expansion in an engine
146
The molar excess Gibbs free energy, g^E, for a binary liquid mixture at T and P is given by, (g^E/RT) = A . x1. x2, where A is a constant. The corresponding equation for ln y1, where y1 is the activity co-efficient of component 1, is
A . X2^2
147
There is a change in __________ during the phase transition.
volume
148
First law of thermodynamics deals with the
direction of energy transfer.
149
A solute distributes itself between two non-miscible solvents in contact with each other in such a way that, at a constant temperature, the ratio of its concentrations in two layers is constant, irrespective of its total amount". This is
the distribution law.
150
A solid is transformed into vapour without going to the liquid phase at
triple point
151
Standard temperature and pressure (S.T.P.) is
0°C and 750 mm Hg
152
Charles' law for gases states that
V/2 = Constant
153
If heat contents of CH4, C2H4 and C3H8 are -17.9, 12.5 and -24.8 kcal/mole respectively, than ΔH for the reaction CH4(g) + C2H4(g) C3H8(g) will be __________ Kcal.
-19.4
154
At 60° C, vapour pressure of methanol and water are 84.562 kPa and 19.953 kPa respectively. An aqueous solution of methanol at 60° C exerts a pressure of 39.223 kPa; the liquid phase and vapour phase mole fractions of methanol are 0.1686 and 0.5714 respectively. Activity co-efficient of methanol is
1.572
155
Gases are cooled in Joule-Thomson expansion, when it is __________ inversion temperature.
below
156
Which of the following behaves most closely like an ideal gas ?
He
157
When a system is in equilibrium for all possible processes, the differential or finite change of entropy is
< 0
158
Degree of freedom of the system ice-water-vapour will be
0
159
The third law of thermodynamics states that the
heat capacity of a crystalline solid is zero at absolute zero temperature.
160
In the decomposition of PCl5 represented by, PCl5 ⇌ PCl3 + Cl2, decrease in the pressure of the system will __________ the degree of dissociation of PCl5.
increase
161
Trouton's ratio is given by (where λb, = molal heat of vaporisation of a substance at its normal boiling point, kcal/kmol Tb = normal boiling point, °K )
λb/Tb
162
Compound having large heat of formation is
more stable.
163
Heating of water under atmospheric pressure is an __________ process.
isobaric
164
Solubility of a substance which dissolves with an increase in volume and liberation of heat will be favoured by the
low pressure and low temperature.
165
For a stable phase at constant pressure and temperature, the fugacity of each component in a binary system __________ as its mole fraction increases.
increases
166
Measurement of thermodynamic property of temperature is facilitated by __________ law of thermodynamics.
zeroth
167
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
-RT ln 0.5
168
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.
327
169
Isobaric process means a constant process.
pressure
170
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
Clayperon-Claussius equation
171
The accentric factor of a materical, 'ω', is defined as ω = -log10(Pr^sat)Tr^-1 = 0.7, where, Pr^sat = reduced vapor pressure, Tr = reduced temperature. The value of accentric factor is always
< 1
172
Boyle's law for gases states that
(1) , when temperature & mass of the gas remain constant.
173
Out of the following refrigeration cycles, which one has maximum COP ?
Carnot cycle
174
Pick out the correct statement:
Under reversible conditions, the adiabatic work is less than isothermal work.
175
All gases during throttling process at atmospheric temperature and pressure show a cooling effect except
H2
176
Compressibility factor for almost all the gases are approximately same at the same
reduced pressure and reduced temperature.
177
Pick out the correct statement.
Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio.
178
A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system
U and S both decreases
179
Pick out the wrong statement.
The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state.
180
The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are
one
181
For a real gas, the chemical potential is given by
RT dlnf
182
The thermodynamic law, PVy = constant, is not applicable in case of
free expansion of an ideal gas.
183
Specific heat of a gas for a reversible adiabatic process is
zero
184
A system is said to be isopiestic, if there is no __________ change.
pressure
185
The unity of Planck's constant 'h' in the equation, E = hv is
J.S
186
Co-efficient of Performance (COP) of a refrigerator is the ratio of the
refrigeration obtained to the work required.
187
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
0
188
dW and dq are not the exact differential, because q and W are
path functions
189
Melting of ice exemplifies a/an
endothermic reaction.
190
At __________ point, all the three phases (i.e.solid, liquid and gas) co-exist.
triple
191
__________ explains the equilibrium constant for any chemical reaction.
Law of mass action
192
The standard Gibbs free energy change of a reaction depends on the equilibrium
temperature
193
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.
28.3
194
Which of the following is an undesirable characteristics of a refrigerant ?
It should have a sub-atmospheric vapor pressure at the temperature in refrigerator coils.
195
What is the ratio of adiabatic compressibility to isothermal compressibility ?
< 1
196
Pick out the wrong statement.
Heat and work are both state function.
197
When dilute aqueous solutions of two salts are mixed, the process is associated with
increase in temperature.
198
Requisites of a reversible process is that the
friction in the system should be absent.
199
The number of degree of freedom for an azeotropic mixture of ethanol and water in vapour-liquid equilibrium, is
1
200
At constant temperature and pressure, for one mole of a pure substance, the ratio of the free energy to the chemical potential is
one
201
Work done is a
path function
202
The free energy change for a chemical reaction is given by (where, K = equilibrium constant)
-RT lnK
203
Free energy, fugacity and activity co-efficient are all affected by change in the temperature. The fugacity co-efficient of a gas at constant pressure ____with the increase of reduced temperature.
increases
204
The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called the __________ temperature.
Boyle
205
For a single component two phase mixture, the number of independent variable properties are
one
206
At normal boiling point, molar entropy of vaporisation is __________ Joule/K°.mole.
92
207
For an ideal solution, the value of activity co-efficient is
1
208
Joule-Thomson co-efficient for a perfect gas is
positive
209
Duringthe phase transition, __________ changes.
volume
210
In an isothermal process on an ideal gas, the pressure increases by 0.5 percent. The volume decreases by about __________ percent.
0.5
211
One ton of refrigeration is defined as the heat rate corresponding to melting of one ton of ice in one
day
212
Which of the following will increase the volume of a real gas by four times ?
Reducing pressure to one fourth at constant temperature.
213
In case of a close thermodynamic system, there is __________ across the boundaries.
no mass transfer but heat transfer
214
As the temperature is lowered towards the absolute zero, the value of (1), then approaches
zero
215
Generation of heat by friction is an example of a/an __________ change.
irreversible
216
A domestic refrigerator has a/an __________ cooled condenser.
air
217
Ideal refrigeration cycle is
same as reverse Carnot cycle.
218
The specific heat of saturated water vapour at 100°C is
-ve
219
For water at 300°C, it has a vapour pressure 8592.7 kPa and fugacity 6738.9 kPa Under these conditions, one mole of water in liquid phase has a volume of 25.28 cm^3 and that in vapour phase in 391.1 cm^3.Fugacity of water (in kPa) at 9000 kPa will be
6753.5
220
If the heat of solution of an ideal gas in a liquid is negative, then its solubility at a given partial pressure varies with the temperature as
solubility increases as temperature decreases.
221
A large iceberg melts at the base, but not at the top, because of the reason that
due to the high pressure at the base, its melting point reduces.
222
Gibbs free energy of a pure fluid approaches __________ as the pressure tends to zero at constant temperature.
minus infinity
223
As the entropy of the universe is increasing, day by day, the work producing capacity of a heat engine is
decreasing
224
The expression for the work done for a reversible polytropic process can be used to obtain the expression for work done for all processes, except reversible __________ process.
isothermal
225
Number of phases in a colloidal system are
2
226
Free energy changes for two reaction mechanism 'X' and 'Y are respectively - 15 and - 5 units. It implies that X is
faster than Y
227
Specific volume of an ideal gas is
the reciprocal of its density.
228
Pick out the extensive property out of the following.
Free energy
229
Entropy change of the reaction, H2O(liquid) H2O(gas), is termed as the enthalpy of
vaporisation
230
Which law of the thermodynamics provids basis for measuring the thermodynamic property ?
Zeroth law
231
Gibbs free energy per mole for a pure substance is equal to the
chemical potential
232
For a constant volume process
dE = CvdT
233
Pick out the wrong statement:
An isometric process is a constant pressure process.
234
The equation relating E, P, V and T which is true for all substanes under all conditions is given by (1) .This equation is called the
thermodynamic equation of state.
235
The partial molar enthalpy of a component in an ideal binary gas mixture of composition Z, at a temperature T and pressure P, is a function only of
T and P
236
Which of the following is not a common refrigerant ?
Ethylene
237
The most important application of distribution law is in
liquid extraction
238
Which is an example of closed system ?
Lquid cooling system of an automobile
239
Work done in case of free expansion is
zero
240
Chemical potential (an intensive property) of a substance is a force that drives the chemical system to equilibrium and is equal to its partial molar properties. The reatio of chemical potential to free energy of a pure substance at oconstant temperature and pressure is
1
241
In which of the following reaction equilibria, the value of equilibrium constant Kp will be more than is Kc ?
N2O4 ⇌ 2NO2
242
COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about
3.5
243
In a P-V diagram (for an ideal gas), an isothermal curve will coincide withan adiabatic curve (through a point), when
Cp = Cv
244
Which of the following is not an equation of state?
Clausius Clayperon equation
245
The difference between isothermal compressibility and adiabatic compressibility for an ideal gas is
+ve
246
The expression for entropy change given by, ΔS = - nR ln (P2/P1), holds good for
reversible isothermal volume change.
247
The work done in isothermal compression compared to that in adiabatic compression will be
more
248
Specific __________ does not change during phase change at constant temperature and pressure.
Gibbs energy
249
Entropy change in case of reversible adiabatic process is
zero
250
Melting of ice is an example of an __________ process.
isothermal
251
Rotary lime kiln is an example of a/an __________ system.
open
252
What happens in a reversible adiabatic expansion process ?
Cooling takes place.
253
The ammonia synthesis reaction represented by N2 + 3H2 ⇌ 2NH3 ; ΔH = - 22.4 kcal, is
exothermic
254
The effect of changing the evaporator temperature on COP as compared to that of changing the condenser temperature (in vapour compression refrigeration system) is
more pronounced
255
High pressure steam is expanded adiabati-cally and reversibly through a well insulated turbine, which produces some shaft work. If the enthalpy change and entropy change across the turbine are represented by ΔH and ΔS respectively for this process:
Δ H ≠ 0 and ΔS = 0.
256
Which of the following is not an intensive property ?
Internal energy
257
Entropy change for an irreversible process taking system and surrounding together is
> 0
258
For an incompressible fluid, the __________ is a function of both pressure as well as temperature.
enthalpy
259
What is the degree of freedom for a system comprising liquid water equilibrium with its vapour ?
1
260
Gibbs free energy (F) is defined as
F = H - TS
261
Pick out the wrong statement.
With increase in temperature, the equilibrium constant increases for an exothermic reaction.
262
A gas mixture of three components is brought in contact with a dispersion of an organic phase in water. The degree of freedom of the system are
3
263
The minimum number of phases that can exist in a system is
1
264
Enthalpy changes over a constant pressure path are always zero for __________ gas.
a perfect
265
The fugacity of a gas in a mixture is equal to the product of its mole fraction and its fugacity in the pure state at the total pressure of the mixture". This is
called Lewis-Randall rule
266
__________ does not change during phase transformation processes like sublimation, melting & vaporisation.
Gibbs free energy
267
Which one is true for a throttling process ?
The inversion temperature is different for different gases.
268
One mole of nitrogen at 8 bar and 600 K is contained in a piston-cylinder arrangement. It is brought to 1 bar isothermally against a resisting pressure of 1 bar. The work done (in Joules) by the gas is
10373
269
In the equation, PVn = constant, if the value of n is in between 1 and y (i.e. Cp/Cv), then it represents a reversible __________ process.
polytropic
270
Throttling process is a/an __________ process.
irreversible and constant enthalpy
271
Helmholtz free energy (A) is defined as
A = E - TS
272
As pressure approaches zero, the ratio of fugacity to pressure (f/P) for a gas approaches
unity
273
For any system, what is the minimum number of degrees of freedom?
0
274
At absolute zero temperature, the __________ of the gas is zero.
volume
275
In the equation, PV^n = constant, if the value of n = ± ∞, then it represents a reversible __________ process.
isometric
276
The point at which all the three (solid, liquid and gas) phases co-exist, is known as the __________ point.
triple
277
In an ideal gas mixture, fugacity of a species is equal to its
partial pressure
278
Consider the reaction, C + O2 ⇌ CO2 ;ΔH = - 94 kcal. What will be the value of ΔH for the reaction CO2 C + O2 ?
+ 94 kcal
279
Which is not a state function ?
Work
280
Molar heat capacity of water in equilibrium with ice at constant pressure is __________ Kcal/kg mole . °K
∞
281
For an ideal gas, the internal energy depends upon its __________ only.
temperature
282
Second law of thermodynamics is concerned with the
direction of energy transfer.
283
High __________ is an undesirable property for a good refrigerant.
viscosity
284
A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is
negative
285
Fundamental principle of refrigeration is based on the __________ law of thermodynamics.
second
286
For a spontaneous process, free energy
decreases whereas the entropy increases
287
Which of the following is not an intensive property ?
Heat capacity
288
1st law of thermodynamics is nothing but the law of conservation of
energy
289
In any spontaneous process,
both F and A decreases
290
When pressure is applied on the system, ice<---->water, then
more water will be formed.
291
The four properties of a system viz. P, V, T, S are related by __________ equation.
Maxwell's
292
Any substance above its critical temperature exists as
gas
293
Isentropic process means a constant __________ process.
entropy .
294
(1) is the mathematical expression
co-efficient of thermal expansion.
295
In case of steady flow compression polytropic process (PVn = constant), the work done on air is the lowest, when
n = 1
296
Grams of butane (C4H10) formed by the liquefaction of 448 litres of the gas (measured at (STP) would be
1160
297
Mollier diagram is a plot of
entropy vs. enthalpy
298
The activity of an ideal gas is numerically __________ its pressure.
equal to
299
In a turbine, the fluid expands almost
adiabatically
300
An ideal gas is taken around the cycle ABCA as shown in P-V diagram below :The work done by the gas during the cycle is equal to
3 P1V1
301
In polytropic process (PVn = constant), if n = 1; it means a/an __________ process.
isothermal
302
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
constant
303
For an isothermal reversible compression of an ideal gas
ΔE = ΔH = 0
304
A refrigeration cycle is the same as a __________ cycle,
reversed heat engine
305
Which of the following is not a reversible process ?
Solution of NaCl in water at 50°C.
306
Which of the following exemplifies an adiabatic process ?
Sudden bursting of a cycle tube.
307
Entropy, which is a measure of the disorder of a system is
zero at absolute zero temperature for a perfect crystalline substance.
308
Critical temperature is defined as the temperature above which a gas will
never liquify however high the pressure may be.
309
Which of the following is not an extensive property ?
Refractive index
310
Chemical engineering thermodynamics is concerned with the __________ in/of chemical processes.
energy transformation from one form to the another
311
An isolated system can exchange __________ with its surroundings.
neither matter nor energy
312
Pick out the wrong statement.
The chemical potential of ith species (μi) in an ideal gas mixture approaches zero as the pressure or mole fraction (xi) tends to be zero at constant temperature.
313
In the reaction; N2 + O2 (1) 2NO, increasing the pressure will result in
no change in equilibrium condition.
314
Pick out the wrong statement.
An equation relating pressure, volume and temperature of a gas is called ideal gas equation.
315
Work done in an adiabatic process between two states depends on the
end states only
316
The change in __________ is equal to the reversible work for compression in steady state flow process under isothermal condition.
Gibbs free energy
317
Extensive properties of a thermodynamic system depend upon the __________ of the system.
mass
318
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
remain unaltered
319
__________ law of thermodynamics ascertains the direction of a particular spontaneous process.
Second
320
Partial molal quantities are important in the study of
non-ideal mixtures
321
Enthalpy 'H' is defined as
H - E = PV
322
In an irreversible process
Tds - dE + dW< 0
323
What is the number of degree of freedom for a system of two miscible non-reacting species in vapor-liquid equilibrium forming an azeotrope ?
1
324
Claude gas liquefaction process employs cooling
by expansion in an engine.
325
Joule-Thomson Co-efficient at any point on the inversion curve is
0
326
Pick out the wrong statement.
Thermal efficiency of a Carnot engine depends upon the properties of the working fluid besides the source & sink temperatures.
327
(1) is the mathematical expression for
Joule-Thompson co-efficient.
328
For an ideal gas, the activity co-efficient is
unity at all pressures.
329
If we increase the pressure on a substance (which is at its triple point), then the triple point
remains unchanged
330
In an ideal refrigeration cycle, the change in internal energy of the fluid is
0
331
The value of Joule-Thomson co-efficient, in case where cooling occurs after the throttling process is
+ve
332
For a multicomponent system, the term chemical potential is equivalent to the
partial molar free energy.
333
The change in Gibbs freee energy for vaporisation of a pure substance is
zero
334
What is the degree of freedom for two mis-cible (non-reacting) substances in vapor-liquid equilibrium forming an azeotrope ?
2
335
A system undergoes a change from a given initial state to a given final state either by an irreversible process or by a reversible process, then(where, Δ S1 and Δ SR are the entropy changes of the system for the irreversible and reversible processes respectively)
Δ S1 is always > Δ SR
336
What is the value of Joule-Thomson co-efficient for an ideal gas ?
0
337
A two stage compressor is used to compress an ideal gas. The gas is cooled to the initial temperature after each stage. The intermediate pressure for the minimum total work requirement should be equal to the __________ mean of P1 and P2.(where, P1 and P2 are initial and final pressures respectively)
geometric
338
Consider the process A & B shown in the figure given below (1) In this case, it is possilbe that
process A is isothermal while B is adiabatic.
339
The amount of heat required to decompose a compound into its elements is __________ the heat of formation of that compound from its elements.
same as
340
In case of the decomposition of hydroiodic acid (2HI ⇌ H2 + I2), addition of H2 (at equilibrium condition) will
diminish the degree of dissociation of HI.
341
In any spontaneous process, the __________ free energy decreases.
both a & b
342
Absolute zero temperature signifies the
temperature of the heat reservoir to which a Carnot engine rejects no heat.
343
For an exothremic reaction
both ΔH and ΔE are negative.
344
For an isothermal process, the internal energy of a gas
remains unchanged
345
The first law of thermodynamics is a statement of conservation of
energy
346
"Dry ice" is
solid carbon dioxide
347
For an ideal gas, the enthalpy
is independent of pressure.
348
Pick out the correct statement.
All the natural processes are reversible in nature.
349
At a given temperature, the volume of a gas dissolved in a solvent __________ with increase in pressure.
remains unchanged
350
A thermodynamic system is taken from state A to B along ACB and is brought back to A along BDA as shown below in the P-V diagram. (1) The net work done during the complete cycle is given by the area covered by
ACBDA
351
Change of heat content when one mole of compound is burnt in oxygen at constant pressure is called the
heat of combustion
352
The chemical potential for a pure substance is __________ its partial molal free energy.
equal to
353
The number of degrees of freedom for a mixture of ice and water (liquid) are
1
354
Domestic refrigerator usually works on the __________ refrigeration cycle.
absorption
355
Minimum number of phases that exists in a system is 1. Number of chemical species in a colloidal system is
2
356
The internal energy of a gas obeying P (V - b) RT (where, b is a positive constant and has a constant Cv), depends upon its
temperature
357
A/an __________ system is exemplified by a vessel containing a volatile liquid in contact with its vapor.
open
358
The Joule-Thomson co-efficient is defined as (∂T/∂P)H. Its value at the inversion point is
0
359
Fugacity of a component in an ideal gas mixture is euqal to the partial pressure of that component in the mixture. The fugacity of each component in a stable homogeneous solution at contant pressure and temperature __________ as its mole fraction increases.
increases
360
At triple point (for one component system), vapour pressure of solid as compared to that of liquid will be
same
361
4 kg moles of an ideal gas expands in vacuum spontaneously. The work done is
0
362
A gas shows deviation from ideal behaviour at
low temperature and high pressure.
363
For a constant pressure reversible process, the enthalpy change (ΔH) of the system is
integ Cv.dT
364
When liquid and vapour phases of one component system are in equilibrium (at a given temperature and pressure), the molar free energy is
same in both the phases.
365
Heat evolved/absorbed during conversion of a substance from one allotropic form to another is termed as the heat of
transition
366
Sublimation temperature of dry ice (solid CO2) is __________ °C.
-78
367
If atmospheric temperature and dew point are nearly equal, then the relative humidity is
almost 100%
368
In reactions involving solids and liquids (where change in volume is negligible), the heat of reaction at constant pressure as compared to that at constant volume is
same
369
Mollier chart is a __________ plot.
enthalpy vs entropy
370
Variation of equilibrium pressure with temperature for any two phases of a given substances is given by the __________ equation.
Clayperon
371
The fusion of a crystalline solid at its melting point to form a liquid at the same temperature is accompanied by
increase in enthalpy corresponding to absorption of heat.
372
Heat of reaction is
dependent on both pressure and temperature.
373
The expression, , is for the____of an ideal gas.
work done under isothermal condition
374
On a P-V diagram of an ideal gas, suppose a reversible adiabatic line intersects a reversible isothermal line at point A. Then at a point A, the slope of the reversible adiabatic line (∂P/∂V)s and the slope of the reversible isothermal line (∂P/∂V)T are related as (where, y = Cp/Cv)
(∂P/∂V)S = y(∂P/∂V)T
375
Pick out the wrong statement.
The entropy of the universe tends to a maximum.
376
In the equation PVn = constant, if the value of n = y = Cp/Cv, then it represents a reversible __________ process.
isentropic
377
Absorption/evolution of heat during conversion of a substance from one allotropic form to another is termed as the heat of
transition
378
For a reversible process involving only pressure-volume work
(dF)T, p = 0
379
One ton of refrigeration capacity is equivalent to the heat removal rate of
200 BTU/minute
380
Equilibrium constant of a reaction varies with the
temperature.
381
A refrigerator works on the principle of __________ law of thermodynamics.
second
382
The adiabatic throttling process of a perfect gas is one of constant enthalpy
which can be performed in a pipe with a constriction.
383
For spontaneous changes in an isolated system (S = entropy)
ds > 0
384
A gas performs the maximum work, when it expands
isobarically
385
Which of the following is Virial equation of state?
PV = A + B/V + C/V^2 + D/V^3 + ...
386
Pressure-enthalpy chart is useful in refrigeration. The change in internal energy of an ideal fluid used in ideal refrigeration cycle is
zero
387
1m^3 of an ideal gas at 500 K and 1000 kPa expands reversibly to 5 times its initial volume in an insulated container. If the specific heat capacity (at constant pressure) of the gas is 21 J/mole . K, the final temperature will be
274 K
388
For a thermodynamic system containing 'x' chemical species, the maximum number of phases that can co-exist at equilibrium is
x + 2
389
A reasonably general expression for vapour-liquid phase equilibrium at low to moderate pressure is Φi yi P = Yi xi fi° where, Φ is a vapor fugacity component, Yi is the liquid activity co-efficient and fi° is the fugacity of the pure component i. the Ki value (Yi = Ki xi) is therefore, in general a function of
temperature, pressure and liquid composition xi only.
390
Normal temperature and pressure (N.T.P.) corresponds to
20°C and 760 mm Hg.
391
Lenz's law results from the law of conservation of
energy
392
The main feature of Carnot refrigeration cycle is that, it
accomplishes the reverse effect of the heat engine.
393
The variation of heat of reaction with temperature at constant pressure is given by the __________ law.
Kirchoffs
394
Entropy of a substance remains constant during a/an __________ change.
reversible adiabatic
395
PVy = constant, holds good for an isentropic process, which is
reversible and adiabatic.
396
A system is said to be at equilibrium, if the entropy of the system has reached __________ value.
maximum
397
For an ideal liquid solution, which of the following is unity ?
Activity co-efficient
398
Cp of a gas at its critical temperature and pressure
equals 1 kcal/kmol °K.
399
Which of the following is true for Virial equation of state ?
Virial co-efficients are function of temperature only.
400
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 ?
Carnot refrigeration cycle.
401
In a working refrigerator, the value of COP is always
> 1
402
Pick out the wrong statement pertaining to the decomposition of PCl5 represented by, PCl5 ⇌ PCl3 + Cl2.Degree of dissociation of PCl5 will
none of these
403
In a reversible chemical reaction (where, Δx = number of moles of products-number of moles of reactants )
all of these
404
Which of the following is a thermodynamic property of a system ?
Entropy
405
Pick out the wrong statement.
The fugacity co-efficient is zero for an ideal gas.
406
The co-efficient of performance (COP) of a refrigerating system, which is its index of performance, is defined as the ratio of useful refrigeration to the net work. The units of __________ and COP are the same.
none of these
407
The chemical potential of a component (μi) of a phase is the amount by which its capacity for doing all work, barring work of expansion is increased per unit amount of sustance added for an infinitesimal addition at constant temperature and pressure. It is given by
all of these
408
Which is not a refrigerant ?
C2H4Cl2
409
If the pressure on 100 c.c. of air is halved, then its volume (at the same temperature) would be __________ c.c.
200
410
Pick out the correct statement.
The heat of formation of a compound is defined as the heat of reaction leading to the formation of the compound from its reactants.
411
is the mathematical expression for
none of these
412
Specific/molar Gibbs free energy for a pure substance does not change during
either (a), (b) or (c)
413
(1) is the mathematical expression for
none of these
414
Which of the following units is not present in both the vapor compression refrigeration system and absorption refrigeration system ?
Compressor
415
Pick out the wrong statement.
none of the above.
416
Gibbs-Duhem equation relates composition in liquid phase and the __________ at constant temperature & pressure.
(a), (b), and (c)
417
"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
none of these.
418
Compressibility factor of a gas is
unity, if it follows PV = nRT.
419
Pick out the correct statement.
Maximum work is done under reversible conditions.
420
The energy of activation of exothermic reaction is
not possible to predict.
421
When a gas is subjected to adiabatic expansion, it gets cooled due to
energy spent in doing work.
422
Joule-Thomson effect i.e., a throttling process is a constant __________ process.
enthalpy
423
The internal energy of an ideal gas is a function of its __________ only.
temperature
424
In the reaction, H2 +I2 ⇌ 2HI, addition of an inert gas will
not effect the equilibrium conditions
425
Pick out the wrong statement.
The accentric factor for all materials is always more than one.
426
Claussius-Clayperon equation gives accurate result, when the
all of these
427
Which of the following is not a unit of the equilibrium constant Kp? (where, Δx = number of moles of products number of moles of reactants)
(atm)Δx2, when Δx > 0
428
Pick out the correct statement.
all of these
429
PVγ = Constant (where, γ = Cp/Cv) is valid for a/an __________ process.
adiabatic
430
Which of the following is not affected by temperature changes ?
None of these
431
Free energy
all of these
432
The following heat engine produces power of 100000 kW. The heat engine operates between 800 K and 300 K. It has a thermal efficiency equal to 50% of that of the Carnot engine for the same temperature. The rate at which heat is absorbed from the hot reservoir is
320, 000 kW
433
Filling of gas from a high pressure cylinder into small bottles is an example of a/an __________ process.
unsteady
434
At the critical point of a substance
all of these
435
y = specific heat ratio of an ideal gas is equal to
all of these
436
An irreversible process
yields an amount of work less than that of a reversible process.
437
Free energy change of mixing two liquid substances is a function of the
all of these
438
Pick out the wrong statement.
none of these
439
The kinetic energy of gas molecule is zero at
-273°C
440
The necessary and sufficient condition for equilibrium between two phases is
the chemical potential of each component should be same in the two phases.
441
Gibbs free energy at constant pressure and temperature under equilibrium conditions is
minimum
442
__________ calorimeter is normally used for measuring the dryness fraction of steam, when it is very low.
A combination of separating & throttling
443
The equation DU = Tds - PdV is applicable to infinitesimal changes occuring in
a closed system with changes in composition.
444
Cv for an ideal gas
is independent of both pressure and volume.
445
In a homogeneous solution, the activity co-efficient of a component depends upon the
all of these
446
The chemical potential of any constituent of an ideal solution depends on the __________ of the solution.
all of these
447
Fugacity and pressure are numerically equal, when the gas is
in ideal state
448
Specific __________ does not change during a phase change (e.g. sublimation, melting, vaporisation etc.).
Gibbs free energy
449
Pick out the wrong statement.
none of these.
450
For the gaseous phase chemical reaction, C2H4(g) + H2O(g) ⇌ C2H5OH(g), the equilibrium conversion does not depend on the
none of these.
451
Pick out the correct statement.
A real gas on expansion in vacuum cools down whereas ideal gas remains unaffected.
452
Gibbs free energy of mixing at constant pressure and temperature is always
- ve
453
The compressibility factor for an ideal gas is 1. Its value for any other real gas is
either (b) or (c), depends on the nature of the gas
454
If two gases have same reduced temperature and reduced pressure, then they will have the same
none of these
455
During adiabatic expansion of gas
none of these.
456
Which of the following has the minimum value of COP for a given refrigeration effect?
Air refrigeration cycle.
457
__________ decreases during adiabatic throttling of a perfect gas.
Pressure
458
Pick out the wrong statement.
Enthalpy and internal energy change is zero during phase change processes like melting, vaporisation and sublimation.
459
Clausius - Clayperon equation is applicable to __________ equilibrium processes.
all of these
460
"When a gas is expanded from high pressure region to low pressure region ; temper -ature change occurs". This phenomenon is related to the
Joule-Thomson effect
461
In the ammonia synthesis reaction, N2 + 3H2 ⇌ 2NH3 + 22.4 kcal, the formation of NH3 will be favoured by
both low temperature and high pressure.
462
Entropy change for an irreversible isolated system is
> 0
463
The unit of equilibrium constant of a chemical reaction is the same as that of
none of these
464
Entropy is a/an
none of these
465
Which of the following is not correct for a reversible adiabatic process ?
none of these
466
Pick out the undesirable property for a good refrigerant.
high viscosity
467
Degree of freedom of a system consisting of a gaseous mixture of H2 and NH3 will be
3
468
Fugacity co-efficient of a substance is the ratio of its fugacity to
activity co-efficient
469
Which of the following identities can be most easily used to verify steam table data for superheated steam.
(∂V/∂T)P = -(∂S/∂P)T
470
All gases except __________ shows a cooling effect during throttling process at atmospheric temperature and pressure.
hydrogen
471
Gibbs phase rule finds application, when heat transfer occurs by
condensation
472
Ideal gas law is applicable at
high T, low P
473
In a homogeneous solution, the fugacity of a component depends upon the
all of these
474
The expression for entropy change given by, ΔS = nR ln (V2/V1) + nCv ln (T2/T1) is valid for
simultaneous heating and expansion of an ideal gas.
475
The second law of thermodynamics states that
none of the above.
476
Internal energy of an ideal gas
none of these.
477
Pick out the wrong statement.
Claussius-clayperon equation is not applicable to melting process.
478
Which of the following is affected by the temperature ?
all of these
479
Henry's law is closely obeyed by a gas, when its __________ is extremely high.
none of these
480
Choose the condition that must be specified in order to liquify CO2 (triple point for CO2 is - 57°C and 5.2 atm).
Pressure and temperature must be kept below 5.2 atm. and - 57°C respectively.
481
Which of the following equations is used for the prediction of activity co-efficient from experiments ?
all of these
482
The equation, , applicable to a binary solution of components. A and B in equilibrium with their vapors at constant temperature and pressure is called the __________ equation.
Gibbs-Duhem-Margules
483
In the reaction, C + O2 → CO2 ; ΔH = - 94 kcal. What is the heat content (enthalpy)of O2?
zero
484
A system in which there is exchange of energy but not of mass, is called a/an __________ system.
closed
485
To obtain integrated form of Clausius-Clayperon equation,(1), from the exact Clayperon equafion, it is assumed that the
all of these.
486
In case of an __________ process, the temperature of the system increases.
adiabatic compression
487
A gas can be liquified by pressure alone only, when its temperature is __________ its critical temperature.
less than or equal to
