ChE Thermodynamics - INDIABIX Flashcards
(153 cards)
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
Heating of water under atmospheric pressure is an __________ process.
A
isobaric
4
Q
Van Laar equation deals with the activity coefficients in
(HINDI BA TO VDW??)
A
binary solutions
5
Q
High __________ is an undesirable property for a good refrigerant.
A
viscosity
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
7
Q
Entropy is a measure of the __________ of a system.
A
disorder
8
Q
A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is
A
negative
9
Q
Fundamental principle of refrigeration is based on the __________ law of thermodynamics.
A
second
10
Q
For a spontaneous process, free energy
A
decreases whereas the entropy increases
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
12
Q
In a working refrigerator, the value of COP is always
A
> 1
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)
14
Q
A refrigerator may be termed as a
A
heat pump
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
16
Q
Which of the following is not an intensive property ?
A
heat capacity
17
Q
Out of the following refrigeration cycles, which one has the minimum COP (Co-efficient of performance)?
A
air cycle
18
Q
Measurement of thermodynamic property of temperature is facilitated by __________ law of thermodynamics.
A
zeroth
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
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
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)
22
Q
Isobaric process means a constant process.
A
pressure
23
Q
No work is done by the system, when a reaction occurs at constant
A
volume
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
25
The freezing point of a liquid decreases when the pressure is increased, if the liquid __________ while freezing.
Contracts
26
At the absolute zero temperature, the entropy of every perfectly crystalline substance becomes zero". This follows from the
third law of thermodynamics
27
During Joule-Thompson expansion of gases
enthalpy remains constant.
28
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
< 1
29
Degrees of freedom at triple point will be
0
30
"Law of corresponding states" says that
two different gases behave similarly, if their reduced properties (i.e. P, V and T) are same.
31
Linde gas liquefaction process employs cooling
by throttling
32
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
none of these
33
Joule-Thomson experiment is
A. isobaric
B. adiabatic
C. isenthalpic
D. both(b) & (c)
both(b) & (c)
34
1st law of thermodynamics is nothing but the law of conservation of
energy
35
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'.
all 'a', 'b' & 'c'.
36
Out of the following refrigeration cycles, which one has maximum COP ?
Carnot cycle
37
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
Under reversible conditions, the adiabatic work is less than isothermal work.
38
In any spontaneous process,
both F and A decreases
39
Which of the following is a thermodynamic property of a system ?
Entropy
40
Equilibrium constant decreases as the temperature
increases, for an exothermic reaction.
41
All gases during throttling process at atmospheric temperature and pressure show a cooling effect except
H2
42
Compressibility factor for almost all the gases are approximately same at the same
reduced pressure and reduced temperature.
43
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.
The fugacity co-efficient is zero for an ideal gas.
44
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.
Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio.
45
When pressure is applied on the system, ice water, then
more water will be formed.
46
Partial molar free energy of an element A in solution is same as its
chemical potential
47
Free energy change at equilibrium is
zero
48
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.
accomplishes both (a) and (b).
49
The temperature at which both liquid and gas phases are identical, is called the __________ point.
critical
50
What is the value of ln y (where y = activity co-efficient) for ideal gases ?
Zero
51
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
52
Which is not a refrigerant ?
A. SO2
B. NH3
C. CCl2F2
D. C2H4Cl2
C2H4Cl2
53
The partial pressure of each constituent present in an alloy is __________ the total vapor pressure exerted by the alloy.
less than
54
Heat is added at constant pressure in an ideal __________ cycle.
A. Stirling
B. Brayton
C. Rankine
D. both (b) and (c)
both (b) and (c)
55
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)
both (a) and (b)
56
The four properties of a system viz. P, V, T, S are related by __________ equation.
Maxwell's
57
If the pressure on 100 c.c. of air is halved, then its volume (at the same temperature) would be __________ c.c.
200
58
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.
The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state.
59
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).
both (a) and (b)
60
The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are
one
61
Any substance above its critical temperature exists as
gas
62
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
Melting point of ice
63
Isentropic process means a constant __________ process.
entropy
64
In case of steady flow compression polytropic process (PVn = constant), the work done on air is the lowest, when
n = 1
65
A liquid under pressure greater than its vapour pressure for the temperature involved is called a __________ liquid.
subcooled
66
For a real gas, the chemical potential is given by
RT dlnf
67
At absolute zero temperature, all substances have the same
heat capacity
68
Lowering of condenser temperature (keeping the evaporator temperature constant) in case of vapour compression refrigeration system results in
increased COP
69
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.
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
Grams of butane (C4H10) formed by the liquefaction of 448 litres of the gas (measured at (STP) would be
1160
71
The thermodynamic law, PV^y = constant, is not applicable in case of
ideal compression of air.
free expansion of an ideal gas.
72
Mollier diagram is a plot of
entropy vs. enthalpy
73
The activity of an ideal gas is numerically __________ its pressure.
equal to
74
When a gas in a vessel expands, its internal energy decreases. The process involved is
reversible
75
A system is said to be isopiestic, if there is no __________ change.
pressure
76
In a turbine, the fluid expands almost
adiabatically
77
The unity of Planck's constant 'h' in the equation, E = hv is
J-s
(joule-seconds)
78
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)
either (a), (b) or (c)
79
Refrigeration capacity of a household refrigerator may be round about __________ tons.
0.15
80
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)
both (b) and (c)
81
In polytropic process (PV^n = constant), if n = 1; it means a/an __________ process.
isothermal
82
The melting point of paraffin wax (which contracts on solidification) __________ with pressure rise.
increases
83
Co-efficient of Performance (COP) of a refrigerator is the ratio of the
refrigeration obtained to the work required.
84
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
85
dW and dq are not the exact differential, because q and Ware
state functions
path functions
86
Trouton's ratio of __________ liquids is calculated using Kistiakowsky equation.
A. polar
B. non-polar
C. both (a) & (b)
D. neither (a) nor (b)
non-polar
87
Activity co-efficient is a measure of the
departure from ideal solution behaviour.
88
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
89
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
Compressor
90
For an isothermal reversible compression of an ideal gas
ΔE = ΔH = 0
91
Melting of ice exemplifies a/an
endothermic reaction
92
A refrigeration cycle is the same as a __________ cycle,
reversed heat engine
93
At __________ point, all the three phases (i.e. solid, liquid and gas) co-exist.
triple
94
Kopp's rule is used to calculate the heat capacity of
solids
95
__________ explains the equilibrium constant for any chemical reaction.
Law of mass action
96
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.
Solution of NaCl in water at 50°C.
97
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.
none of the above
98
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.
Sudden bursting of a cycle tube.
99
Entropy, which is a measure of the disorder of a system is
zero at absolute zero temperature for a perfect crystalline substance
100
Critical temperature is defined as the temperature above which a gas will
never liquify however high the pressure may be
101
The standard Gibbs free energy change of a reaction depends on the equilibrium
temperature
102
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), (b), and (c)
103
In an ideal solution, the activity of a component equals its
mole fraction
104
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
105
Clapeyron equation deals with the
rate of change of vapour pressure with temperature.
106
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.
None of these.
107
"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.
none of these
108
What is the ratio of adiabatic compressibility to isothermal compressibility ?
< 1
109
The absolute entropy for all crystalline substances at absolute zero temperature is
zero
110
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.
Heat and work are both state function
111
Compressibility factor of a gas is
unity, if it follows PV = nRT.
112
Which of the following is not an extensive property ?
A. Free energy
B. Entropy
C. Refractive index
D. None of these
Refractive index
113
Forward reaction will be favoured for the exothermic reaction, represented by CO + H2O CO2 + H2, by
low temperature and high pressure.
114
Enthalpy of a gas depends upon its
temperature
115
When dilute aqueous solutions of two salts are mixed, the process is associated with
increase in temperature
116
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.
Maximum work is done under reversible conditions.
117
Chemical engineering thermodynamics is concerned with the __________ in/of chemical processes.
energy transformation from one form to the another
118
An isolated system can exchange __________ with its surroundings.
neither matter nor energy
119
Requisites of a reversible process is that the
friction in the system should be absent.
120
Fugacity is most helpful in
representing actual behaviour of real gases.
121
The energy of activation of exothermic reaction is
not possible to predict
122
In the reaction; N2 + O2 -> 2NO, increasing the pressure will result in
no change in equilibrium condition
123
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
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