3. Thermodynamics Flashcards
Maximum work that could be secured by expanding the gas over a given pressure range is the __________ work.
isothermal
Internal energy change of a system over one complete cycle in a cyclic process is
zero
Heating of water under atmospheric pressure is an __________ process.
isobaric
**Van Laar equation **deals with the activity co-efficients in
binary solutions
High ________ is an undesirable property for a good refrigerant.
viscosity
Solubility of a substance which dissolves with an increase in volume and liberation of heat will be favoured by the
low pressure and high temperature.
Entropy is a measure of the __________ of a system.
disorder
A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is
negative
Fundamental principle of refrigeration is based on the __________ law of thermodynamics.
second
For a spontaneous process, free energy
10,decreases whereas the entropy increases
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 ?
11,Carnot refrigeration cycle.
In a working refrigerator, the value of COP is always
12,> 1
A refrigerator may be termed as a
13,heat pump
For a stable phase at constant pressure and temperature, the fugacity of each component in a binary system __________ as its mole fraction increases.
14,increases
Which of the following is not an intensive property ?
15,Heat capacity
Out of the following refrigration cycles, which one has the minimum COP (Co-efficient of performance)?
16,Air cycle
Measurement of thermodynamic property of temperature is facilitated by __________ law of thermodynamics.
17,zeroth
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
18,-RT ln 0.5
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.
19,327
Isobaric process means a constant process.
20,pressure
No work is done by the system, when a reaction occurs at constant
21,volume
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
22,Clayperon-Claussius equation
The freezing point of a liquid decreases when the pressure is increased, if the liquid __________ while freezing.
23,expands
“At the absolute zero temperature, the entropy of every perfectly crystalline substance becomes zero”. This follows from the
24,third law of thermodynamics
During Joule-Thomson expansion of gases
25,enthalpy remains constant.
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
26,< 1
Degress of freedom at triple point will be
27,0
“Law of corresponding states” says that
28,two different gases behave similarly, if their reduced properties (i.e. P, V and T) are same.
Linde gas liquefaction process employs cooling
29,by throttling
Pick out the wrong statement pertaining to the decomposition of PCl5 represented by, PCl5 ⇌ PCl3 + Cl2.Degree of dissociation of PCl5 will
30,decrease on addition of Cl2.
Boyle’s law for gases states that
31,(1) , when temperature & mass of the gas remain constant.
1st law of thermodynamics is nothing but the law of conservation of
32,energy
In a reversible chemical reaction (where, Δx = number of moles of products-number of moles of reactants )
33,all of these
Out of the following refrigeration cycles, which one has maximum COP ?
34,Carnot cycle
Pick out the correct statement:
35,Maximum work is done under reversible conditions.
In any spontaneous process,
36,both F and A decreases
Which of the following is a thermodynamic property of a system ?
37,Entropy
Equilibrium constant decreases as the temperature
38,increases, for an exothermic reaction.
The expression, (1) , gives the free energy change
39,with pressure changes at constant temperature.
All gases during throttling process at atmospheric temperature and pressure show a cooling effect except
40,H2
Compressibility factor for almost all the gases are approximately same at the same
41,reduced pressure and reduced temperature.
Pick out the wrong statement.
42,The fugacity co-efficient is zero for an ideal gas.
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.
43,none of these
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
44,all of these
In jet refrigerators, the refrigerating fluid is practically always
45,water
Water on heating from 1 to 4°C
46,contracts
Pick out the correct statement.
47,Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio.
When pressure is applied on the system, ice<—->water, then
48,more water will be formed.
Partial molar free energy of an element A in solution is same as its
49,chemical potential
Free energy change at equilibrium is
50,zero
The temperature at which both liquid and gas phases are identical, is called the __________ point.
51,critical
What is the value of ln y (where y = activity co-efficient) for ideal gases ?
52,Zero
A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system
53,U and S both decreases
Which is not a refrigerant ?
54,C2H4Cl2
The partial pressure of each constituent present in an alloy is __________ the total vapor pressure exerted by the alloy.
55,less than
The four properties of a system viz. P, V, T, S are related by __________ equation.
56,Maxwell’s
If the pressure on 100 c.c. of air is halved, then its volume (at the same temperature) would be __________ c.c.
57,200
Pick out the wrong statement.
58,The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state.
The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are
59,one
Any substance above its critical temperature exists as
60,gas
Which of the following decreases with increase in pressure ?
61,Melting point of ice
Isentropic process means a constant __________ process.
62,entropy .
(1) is the mathematical expression
63,specific heat at constant pressure (Cp).
In case of steady flow compression polytropic process (PVn = constant), the work done on air is the lowest, when
64,n = 1
A liquid under pressure greater than its vapour pressure for the temperature involved is called a __________ liquid.
65,subcooled
For a real gas, the chemical potential is given by
66,RT dlnf
At absolute zero temperature, all substances have the same
67,entropy
Lowering of condenser temperature (keeping the evaporator temperature constant) in case of vapour compression refrigeration system results in
68,increased COP.
Pick out the correct statement.
69,The heat of formation of a compound is defined as the heat of reaction leading to the formation of the compound from its reactants.
Grams of butane (C4H10) formed by the liquefaction of 448 litres of the gas (measured at (STP) would be
70,1160
The thermodynamic law, PVy = constant, is not applicable in case of
71,free expansion of an ideal gas.
Mollier diagram is a plot of
72,entropy vs. enthalpy
is the mathematical expression for
73,enthalpy change
The activity of an ideal gas is numerically __________ its pressure.
74,equal to
Specific heat of a gas for a reversible adiabatic process is
75,zero
When a gas in a vessel expands, its internal energy decreases. The process involved is
76,irreversible
A system is said to be isopiestic, if there is no __________ change.
77,pressure
In a turbine, the fluid expands almost
78,adiabatically
The unity of Planck’s constant ‘h’ in the equation, E = hv is
79,J.S
Specific/molar Gibbs free energy for a pure substance does not change during
80,either (a), (b) or (c)
Refrigeration capacity of a household refrigerator may be round about __________ tons.
81,1.5
(1) is the mathematical expression for
82,entropy change
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
83,6 P1 V1
In polytropic process (PVn = constant), if n = 1; it means a/an __________ process.
84,isothermal
The melting point of paraffin wax (which contracts on solidification) __________ with pressure rise.
85,increases
Co-efficient of Performance (COP) of a refrigerator is the ratio of the
86,refrigeration obtained to the work required.
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
87,1.26
dW and dq are not the exact differential, because q and W are
88,path functions
Activity co-efficient is a measure of the
89,departure from ideal solution behaviour.
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
90,constant
Which of the following units is not present in both the vapor compression refrigeration system and absorption refrigeration system ?
91,Compressor
For an isothermal reversible compression of an ideal gas
92,ΔE = ΔH = 0
Melting of ice exemplifies a/an
93,endothermic reaction.
A refrigeration cycle is the same as a __________ cycle,
94,reversed heat engine
At __________ point, all the three phases (i.e.solid, liquid and gas) co-exist.
95,triple
Kopp’s rule is used to calculate the heat capacity of
96,solids
__________ explains the equilibrium constant for any chemical reaction.
97,Law of mass action
Which of the following is not a reversible process ?
98,Solution of NaCl in water at 50°C.
Pick out the wrong statement.
99,none of the above.
Which of the following exemplifies an adiabatic process ?
100,Sudden bursting of a cycle tube.
Entropy, which is a measure of the disorder of a system is
101,zero at absolute zero temperature for a perfect crystalline substance.
Critical temperature is defined as the temperature above which a gas will
102,not liquify (barring exceptions).
The standard Gibbs free energy change of a reaction depends on the equilibrium
103,temperature
Gibbs-Duhem equation relates composition in liquid phase and the __________ at constant temperature & pressure.
104,activity co-efficient
In an ideal solution, the activity of a component equals its
105,mole fraction.
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.
106,28.3
Clayperon equation deals with the
107,rate of change of vapour pressure with temperature.
Which of the following is an undesirable characteristics of a refrigerant ?
108,It should have a sub-atmospheric vapor pressure at the temperature in refrigerator coils.
“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
109,statement of Vant-Hoff equation.
What is the ratio of adiabatic compressibility to isothermal compressibility ?
110,> 1
The absolute entropy for all crystalline substances at absolute zero temperature is
111,zero
Pick out the wrong statement.
112,Heat and work are both state function.
Compressibility factor of a gas is
113,unity, if it follows PV = nRT.
Which of the following is not an extensive property ?
114,Refractive index
Forward reaction will be favoured for the exothermic reaction, represented by CO + H2O ⇌ CO2 + H2, by
115,low temperature and high pressure.
Enthalpy of a gas depends upon its
116,temperature
When dilute aqueous solutions of two salts are mixed, the process is associated with
117,change in temperature which is a function of composition.
Pick out the correct statement.
118,Maximum work is done under reversible conditions.
Chemical engineering thermodynamics is concerned with the __________ in/of chemical processes.
119,energy transformation from one form to the another
An isolated system can exchange __________ with its surroundings.
120,neither matter nor energy
Requisites of a reversible process is that the
121,friction in the system should be absent.
Fugacity is most helpful in
122,representing actual behaviour of real gases.
The energy of activation of exothermic reaction is
123,not possible to predict.
Pick out the wrong statement.
124,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.
In the reaction; N2 + O2 (1) 2NO, increasing the pressure will result in
125,no change in equilibrium condition.
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
126,349
Pick out the wrong statement.
127,An equation relating pressure, volume and temperature of a gas is called ideal gas equation.
When a gas is subjected to adiabatic expansion, it gets cooled due to
128,energy spent in doing work.
Joule-Thomson effect i.e., a throttling process is a constant __________ process.
129,enthalpy
In the equation, PV^n = Constant, if the value of n = 0, then it represents a reversible __________ process.
130,isobaric
Work done in an adiabatic process between two states depends on the
131,end states only
The number of degree of freedom for an azeotropic mixture of ethanol and water in vapour-liquid equilibrium, is
132,1
The internal energy of an ideal gas is a function of its __________ only.
133,temperature
At constant temperature and pressure, for one mole of a pure substance, the ratio of the free energy to the chemical potential is
134,one
The change in __________ is equal to the reversible work for compression in steady state flow process under isothermal condition.
135,Gibbs free energy
Work done is a
136,path function
Extensive properties of a thermodynamic system depend upon the __________ of the system.
137,mass
Near their critical temperatures, all gases occupy volumes __________ that of the ideal gas.
138,more than
The free energy change for a chemical reaction is given by (where, K = equilibrium constant)
139,-RT lnK
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.
140,increases
In the reaction, H2 +I2 ⇌ 2HI, addition of an inert gas will
141,not effect the equilibrium conditions
What is the number of degrees of freedom for liquid water in equilibrium with a mixture of nitrogen and water vapor ?
142,1
The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called the __________ temperature.
143,Boyle
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
144,remain unaltered
All gases above its inversion temperature, in a throttling process will show
145,a heating effect.
First law of thermodynamics is mathematically stated as
146,dQ = dE + dW
Pick out the wrong statement.
147,The accentric factor for all materials is always more than one.
Translational kinetic energy of molecules of an ideal gas is proportional to (where, T = absolute temperature of the gas )
148,T
Equation which relates pressure, volume and temperature of a gas is called the
149,equation of state
Claussius-Clayperon equation gives accurate result, when the
150,all of these
The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called __________ temperature.
151,Boyle
For a single component two phase mixture, the number of independent variable properties are
152,one
__________ law of thermodynamics ascertains the direction of a particular spontaneous process.
153,Second
At normal boiling point, molar entropy of vaporisation is __________ Joule/K°.mole.
154,92
For an ideal solution, the value of activity co-efficient is
155,1
The expression, nCv(T2 - T1), is for the __________ of an ideal gas.
156,work done under adiabatic condition
Which of the following is a widely used refrigerant in vapour compression refrigeration system (using large centrifugal compressor)?
157,Ammonia
Internal energy is equal to the heat absorbed in case of a/an __________ process.
158,constant volume
The first law of thermodynamics is a restatement of the law of conservation of
159,energy
Joule-Thomson co-efficient for a perfect gas is
160,zero
In an adiabatic process, the
161,heat transfer is zero.
A nozzle is a device, which
162,increases kinetic energy and decreases pressure.
Duringthe phase transition, __________ changes.
163,all of these
The work done in an adiabatic change in a particular gas depends upon changes in the __________ only.
164,temperature
In an isothermal process on an ideal gas, the pressure increases by 0.5 percent. The volume decreases by about __________ percent.
165,0.5
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)
166,(atm)Δx2, when Δx > 0
Pick out the correct statement.
167,all of these
Partial molal quantities are important in the study of
168,non-ideal mixtures
Number of degrees of freedom for a three phase system in equilibrium comprising of three non-reacting chemical species is
169,2
Critical solution temperature (or the con-solute temperature) for partially miscible liquids (e.g., phenol-water) is the minimum temperature at which
170,a homogeneous solution (say of phenol water) is formed.
Enthalpy ‘H’ is defined as
171,H = E - PV
One ton of refrigeration is defined as the heat rate corresponding to melting of one ton of ice in one
172,day
__________ functions are exemplified by heat and work.
173,Path
In an irreversible process
174,Tds - dE + dW< 0
What is the number of degree of freedom for a system of two miscible non-reacting species in vapor-liquid equilibrium forming an azeotrope ?
175,1
The entropy change in a reversible isothermal process, when an ideal gas expands to four times its initial volume is
176,R loge 4
PVγ = Constant (where, γ = Cp/Cv) is valid for a/an __________ process.
177,adiabatic
Claude gas liquefaction process employs cooling
178,by expansion in an engine.
Which of the following will increase the volume of a real gas by four times ?
179,Reducing pressure to one fourth at constant temperature.
Pick out the wrong statement.
180,A refriferation cycle violates the second law of thermadynamics.
The equation, PV = nRT, is best obeyed by gases at
181,low pressure & high temperature.
Internal energy of an element at 1 atm and 25° C is __________ kcal/kg.mole.
182,0
Which of the following liquid metals has the highest thermal conductivity ?
183,Molten sodium
Which of the following has the least thermal efficiency ?
184,Steam engine
Joule-Thomson Co-efficient at any point on the inversion curve is
185,0
Pick out the wrong statement.
186,The values of (1) are zero for a real gas at its critical point.
Number of components (C), phase (P) and degrees of freedom (F) are related by Gibbs phase rule as
187,P + F - C = 2
The value of Cp & Cv respectively for monoatomic gases in Kcal/kg Mole . °K are
188,5 & 3
(1) is the mathematical expression for
189,specific heat at constant pressure (Cp).
In case of a close thermodynamic system, there is __________ across the boundaries.
190,no mass transfer but heat transfer
During a reversible isothermal expansion of an ideal gas, the entropy change is
191,+ve
As the temperature is lowered towards the absolute zero, the value of (1), then approaches
192,zero
Which of the following is not affected by temperature changes ?
193,Free energy
For an ideal gas, the activity co-efficient is
194,unity at all pressures.
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.
195,ideal
Generation of heat by friction is an example of a/an __________ change.
196,irreversible
A domestic refrigerator has a/an __________ cooled condenser.
197,air
The compressibility factor of a gas is given by (where, V1 = actual volume of the gas V2 = gas volume predicted by ideal gas law )
198,V1/V2
If we increase the pressure on a substance (which is at its triple point), then the triple point
199,remains unchanged
In an ideal refrigeration cycle, the change in internal energy of the fluid is
200,0
Free energy
201,all of these
“If different processes are used to bring about the same chemical reaction, the enthalpy change is same for all of them”. This is __________ law.
202,Hess’s
Fugacity is a measure of the
203,escaping tendencies of the same substance in different phases of a system.
The quantitative effect of temperature on chemical equilibrium is given by the
204,Vant-Hoff equation.
For an irreversible process involving only pressure-volume work
205,(dF)T, p <0
Ideal refrigeration cycle is
206,same as reverse Carnot cycle.
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
207,200, 000 kW
The enthalpy change when ammonia gas is dissolved in water is called the heat of
208,solution
The value of Joule-Thomson co-efficient, in case where cooling occurs after the throttling process is
209,+ve
The specific heat of saturated water vapour at 100°C is
210,0
For a multicomponent system, the term chemical potential is equivalent to the
211,partial molar free energy.
The change in Gibbs freee energy for vaporisation of a pure substance is
212,zero
Critical compressibility factor for all substances
213,are more or less constant (vary from 0.2 to 0.3).
What is the degree of freedom for two mis-cible (non-reacting) substances in vapor-liquid equilibrium forming an azeotrope ?
214,1
For a given substance at a specified temperature, activity is __________ to fugacity.
215,directly proportional
In case of vapour compression refrigeration system, elevating the evaporator temperature (keeping the condenser temperature constant) results in
216,enhanced COP.
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
217,6738.9
As the temperature is lowered towards the absolute zero, the value of the quantity approaches
218,zero
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
219,solubility increases as temperature decreases.
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
220,1
The Carnot co-efficient of performance (COP) of a domestic air conditioner compared to a household refrigerator is
221,less
The unit of fugacity is the same as that of the
222,pressure
Filling of gas from a high pressure cylinder into small bottles is an example of a/an __________ process.
223,adiabatic
A large iceberg melts at the base, but not at the top, because of the reason that
224,due to the high pressure at the base, its melting point reduces.
At the critical point of a substance
225,all of these
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)
226,Δ S1 is always > Δ SR
What is the value of Joule-Thomson co-efficient for an ideal gas ?
227,0
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)
228,geometric
y = specific heat ratio of an ideal gas is equal to
229,Cp/Cv
Consider the process A & B shown in the figure given below (1) In this case, it is possilbe that
230,process A is adiabatic while B is isothermal.
Gibbs free energy of a pure fluid approaches __________ as the pressure tends to zero at constant temperature.
231,minus infinity
As the entropy of the universe is increasing, day by day, the work producing capacity of a heat engine is
232,decreasing
An irreversible process
233,yields an amount of work less than that of a reversible process.
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.
234,isothermal
Free energy change of mixing two liquid substances is a function of the
235,all of these
Pick out the wrong statement.
236,Nicotine-water system shows both an upper as well as a lower consolute temperature, implying that they are partially miscible between these two limiting temperatures.
The total change in the enthalpy of a system is independent of the
237,number of intermediate chemical reactions involved.
Number of phases in a colloidal system are
238,2
Free energy changes for two reaction mechanism ‘X’ and ‘Y are respectively - 15 and - 5 units. It implies that X is
239,faster than Y
Vapour which is at a pressure smaller than the saturation pressure for the temperature involved is called a __________ vapour.
240,superheated
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.)
241,μ° + RT ln f
The kinetic energy of gas molecule is zero at
242,-273°C
Which of the following is not an intensive property ?
243,Volume
The necessary and sufficient condition for equilibrium between two phases is
244,the chemical potential of each component should be same in the two phases.
Specific volume of an ideal gas is
245,the reciprocal of its density.
Pick out the extensive property out of the following.
246,Free energy
Entropy change of the reaction, H2O(liquid) H2O(gas), is termed as the enthalpy of
247,vaporisation
Which law of the thermodynamics provids basis for measuring the thermodynamic property ?
248,Zeroth law
Gibbs free energy per mole for a pure substance is equal to the
249,chemical potential
Gibbs free energy at constant pressure and temperature under equilibrium conditions is
250,0
With increase in pressure (above atmospheric pressure), the Cp of a gas
251,increases
A change in state involving a decrease in entropy can be spontaneous, only if
252,it is exothermic.
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
253,0
__________ calorimeter is normally used for measuring the dryness fraction of steam, when it is very low.
254,Throttling
The amount of heat required to decompose a compound into its elements is __________ the heat of formation of that compound from its elements.
255,more than
For a constant volume process
256,dE = CvdT
In case of the decomposition of hydroiodic acid (2HI ⇌ H2 + I2), addition of H2 (at equilibrium condition) will
257,diminish the degree of dissociation of HI.
In any spontaneous process, the __________ free energy decreases.
258,Gibbs
The equation DU = Tds - PdV is applicable to infinitesimal changes occuring in
259,a closed system of constant composition.
Heat is added at constant temperature in an ideal __________ cycle.
260,Stirling
Pick out the correct equation relating ‘F’ and ‘A’.
261,F = A + TS
In a reversible process
262,Tds = dE + dW
Cv for an ideal gas
263,is independent of both pressure and volume.
In a homogeneous solution, the activity co-efficient of a component depends upon the
264,all of these
Pick out the wrong statement:
265,An isometric process is a constant pressure process.
With increase in compression ratio, the efficiency of the otto engine
266,increases
The chemical potential of any constituent of an ideal solution depends on the __________ of the solution.
267,all of these
Fugacity and pressure are numerically equal, when the gas is
268,in ideal state
Refrigerants commonly used for domestic refrigerators are
269,freon-12
Absolute zero temperature signifies the
270,minimum temperature attainable.
Specific __________ does not change during a phase change (e.g. sublimation, melting, vaporisation etc.).
271,Gibbs free energy
Heat of formation of an element in its standard state is
272,0
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
273,thermodynamic equation of state.
For an exothremic reaction
274,both ΔH and ΔE are negative.
Pick out the wrong statement.
275,If Raoult’s law is applied to one component of a binary mixture ; Henry’s law or Raoult’s law is applied to the other component also.
The shape of T-S diagram for Carnot Cycle is a
276,rectangle
For an isothermal process, the internal energy of a gas
277,remains unchanged
In the equation, PVn = constant, if the value of n = 1, then it represents a reversible __________ process.
278,isothermal
For the gaseous phase chemical reaction, C2H4(g) + H2O(g) ⇌ C2H5OH(g), the equilibrium conversion does not depend on the
279,steam to ethylene ratio.
The first law of thermodynamics is a statement of conservation of
280,energy
“Dry ice” is
281,solid carbon dioxide
Which of the following non-flow reversible compression processes require maximum work ?
282,Adiabatic process
Pick out the correct statement.
283,A real gas on expansion in vacuum cools down whereas ideal gas remains unaffected.
“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
284,Le-Chatelier principle.
Sound waves propagation in air exemplifies an __________ process.
285,adiabatic
For equilibrium process (i.e. reversible) in an isolated system
286,ds = 0
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
287,T, P and Z
With increase in reduced temperature, the fugacity co-efficient of a gas at constant reduced pressure
288,increases
For an ideal gas, the enthalpy
289,is independent of pressure.
Efficiency of a heat engine working on Carnot cycle between two temperature levels depends upon the
290,two temperatures only.
In Joule-Thomson porous plug experiment, the
291,enthalpy does not remain constant.
A Carnot cycle consists of the following steps :
292,Two isothermals and two isentropics.
For a cyclic process, a fixed ratio between heat and work
293,always exists
Which of the following is not a common refrigerant ?
294,Ethylene
The most important application of distribution law is in
295,liquid extraction
Pick out the correct statement.
296,In a closed system, the energy can be exchanged with the surrounding, while. matter can not be exchanged.
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
297,5.2
Gibbs free energy of mixing at constant pressure and temperature is always
298,- ve
The compressibility factor for an ideal gas is 1. Its value for any other real gas is
299,either (b) or (c), depends on the nature of the gas
If two gases have same reduced temperature and reduced pressure, then they will have the same
300,none of these
Which of the following is an extensive property of a system ?
301,Heat capacity
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
302,1
Cp - Cv = R is valid for __________ gases.
303,ideal
At a given temperature, the volume of a gas dissolved in a solvent __________ with increase in pressure.
304,increases
Which is an example of closed system ?
305,Lquid cooling system of an automobile
Melting of wax is accompanied with __________ in entropy.
306,increase
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
307,ACBDA
Work done in case of free expansion is
308,zero
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
309,1
During adiabatic expansion of gas
310,none of these.
Which of the following has the minimum value of COP for a given refrigeration effect?
311,Air refrigeration cycle.
__________ decreases during adiabatic throttling of a perfect gas.
312,Pressure
Pick out the wrong statement.
313,Enthalpy and internal energy change is zero during phase change processes like melting, vaporisation and sublimation.
Tea kept in a thermos flask is vigorously shaken. If the tea is considered as a system, then its temperature will
314,increase
Change of heat content when one mole of compound is burnt in oxygen at constant pressure is called the
315,heat of combustion
Clausius - Clayperon equation is applicable to __________ equilibrium processes.
316,all of these
In which of the following reaction equilibria, the value of equilibrium constant Kp will be more than is Kc ?
317,N2O4 ⇌ 2NO2
After throttling, gas temperature
318,may increase or decrease ; depends on the nature of the gas
The chemical potential for a pure substance is __________ its partial molal free energy.
319,equal to
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
320,same in both the phases.
COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about
321,3.5
The number of degrees of freedom for a mixture of ice and water (liquid) are
322,1
On opening the door of an operating refrigerator kept in a closed room, the temperature of the room will
323,increase
Domestic refrigerator usually works on the __________ refrigeration cycle.
324,vapour-ejection
Gibbs-Duhem equation
325,states that n1dμ1 + n2dμ2 + ….njdμj = 0, for a system of definite composition at constant temperature and pressure.
Minimum number of phases that exists in a system is 1. Number of chemical species in a colloidal system is
326,2
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
327,temperature
“When a gas is expanded from high pressure region to low pressure region ; temper -ature change occurs”. This phenomenon is related to the
328,Joule-Thomson effect
The internal energy of an ideal gas does not change in a reversible __________ process.
329,isothermal
A/an __________ system is exemplified by a vessel containing a volatile liquid in contact with its vapor.
330,closed
In a P-V diagram (for an ideal gas), an isothermal curve will coincide withan adiabatic curve (through a point), when
331,Cp > Cv
For an ideal gas, the chemical potential is given by
332,RT dlnP
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
333,same
In the ammonia synthesis reaction, N2 + 3H2 ⇌ 2NH3 + 22.4 kcal, the formation of NH3 will be favoured by
334,both low temperature and high pressure.
Entropy change for an irreversible isolated system is
335,> 0
Heat requirement for decomposition of a compound into its elements is __________ that is evolved during the formation of that compound from its elements.
336,greater than
The unit of equilibrium constant of a chemical reaction is the same as that of
337,molar concentration
Which of the following equations is obtained on combining 1st and 2nd law of thermodynamics, for a system of constant mass?
338,dE = Tds - PdV
The Joule-Thomson co-efficient is defined as (∂T/∂P)H. Its value at the inversion point is
339,0
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.
340,increases
Entropy is a/an
341,state function
At triple point (for one component system), vapour pressure of solid as compared to that of liquid will be
342,same
4 kg moles of an ideal gas expands in vacuum spontaneously. The work done is
343,0
Which of the following is not correct for a reversible adiabatic process ?
344,none of these
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
345,T1/(T1-T2)
Throttling (Joule-Thomson effect) process is a constant __________ process.
346,enthalpy
Boiling of liquid is accompanied with increase in the
347,all of these
Change of state namely evaportation condensation, freezing and melting is an __________ process.
348,isothermal
Which of the following is not an equation of state?
349,Clausius Clayperon equation
A gas shows deviation from ideal behaviour at
350,low temperature and high pressure.
The difference between isothermal compressibility and adiabatic compressibility for an ideal gas is
351,0
The expression for entropy change given by, ΔS = - nR ln (P2/P1), holds good for
352,reversible isothermal volume change.
With increase in temperature, the internal energy of a substance
353,increases
It is desired to bring about a certain change in the state of a system by performing work on the system under adiabatic conditions.
354,The amount of work needed is path dependent.
For a constant pressure reversible process, the enthalpy change (ΔH) of the system is
355,Cp.dT
The work done in isothermal compression compared to that in adiabatic compression will be
356,more
For organic compounds, group contribution method can be used for the estimation of
357,critical properties.
Specific __________ does not change during phase change at constant temperature and pressure.
358,Gibbs energy
When liquid and vapour phases of one component system are in equilibrium (at a given temperature and pressure), the molar free energy is
359,same in both the phases.
Heat evolved/absorbed during conversion of a substance from one allotropic form to another is termed as the heat of
360,transition
What happens in a reversible adiabatic compression ?
361,Heating occurs
Sublimation temperature of dry ice (solid CO2) is __________ °C.
362,-78
If atmospheric temperature and dew point are nearly equal, then the relative humidity is
363,almost 100%
Entropy change in case of reversible adiabatic process is
364,zero
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
365,same
The efficiency of an Otto engine compared to that of a diesel engine, for the same compression ratio will be
366,more
Mollier chart is a __________ plot.
367,enthalpy vs entropy
Variation of equilibrium pressure with temperature for any two phases of a given substances is given by the __________ equation.
368,Clayperon
Pick out the undesirable property for a good refrigerant.
369,high viscosity
Isotherm on an enthalpy-concentration diagram, for an ideal solution will be a
370,straight line
The fusion of a crystalline solid at its melting point to form a liquid at the same temperature is accompanied by
371,increase in enthalpy corresponding to absorption of heat.
Melting of ice is an example of an __________ process.
372,isothermal
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.
373,448
Rotary lime kiln is an example of a/an __________ system.
374,open
Heat of reaction is
375,dependent on both pressure and temperature.
The expression, , is for the____of an ideal gas.
376,work done under isothermal condition
What happens in a reversible adiabatic expansion process ?
377,Cooling takes place.
Degree of freedom of a system consisting of a gaseous mixture of H2 and NH3 will be
378,3
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)
379,(∂P/∂V)S = y(∂P/∂V)T
Pick out the wrong statement.
380,The entropy of a substance does not remain constant during a reversible adiabatie change.
Fugacity co-efficient of a substance is the ratio of its fugacity to
381,pressure
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.
382,Bomb
As the time is passing, entropy of the universe
383,is increasing
Which of the following processes can not be made reversible even under ideal condition of operation?
384,Free expansion of a gas.
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.
385,Gibbs-Duhem
Which of the following identities can be most easily used to verify steam table data for superheated steam.
386,(∂T/∂P)S = (∂V/∂S)P
In the equation PVn = constant, if the value of n = y = Cp/Cv, then it represents a reversible __________ process.
387,adiabatic
The ammonia synthesis reaction represented by N2 + 3H2 ⇌ 2NH3 ; ΔH = - 22.4 kcal, is
388,exothermic
With increase in temperature, the atomic heat capacities of all solid elements
389,increases
The temperature at the eutectic point of the system is the __________ temperature that can be attained in the system.
390,lowest
The effect of changing the evaporator temperature on COP as compared to that of changing the condenser temperature (in vapour compression refrigeration system) is
391,more pronounced
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
392,partially condensed vapour with quality of 0.9.
An isentropic process is carried out at constant
393,all of these
All gases except __________ shows a cooling effect during throttling process at atmospheric temperature and pressure.
394,hydrogen
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:
395,Δ H ≠ 0 and ΔS = 0.
The necessary condition for phase equilibrium in a multiphase system of N components is that the
396,chemical potentials of a given component should be equal in all phases.
Compressibility factor-reduced pressure plot on reduced co-ordinates facilitates
397,use of only one graph for all gases.
Which of the following is not an intensive property ?
398,Internal energy
Pick out the wrong statement.
399,At constant pressure, solubility of a gas in a liquid increases with rise in temperature.
Gibbs phase rule finds application, when heat transfer occurs by
400,condensation
Absorption/evolution of heat during conversion of a substance from one allotropic form to another is termed as the heat of
401,transition
Ideal gas law is applicable at
402,high T, low P
Reduced pressure of a gas is the ratio of its
403,pressure to critical pressure.
For a reversible process involving only pressure-volume work
404,(dF)T, p = 0
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
405,300(35/7)
Entropy change for an irreversible process taking system and surrounding together is
406,> 0
In a homogeneous solution, the fugacity of a component depends upon the
407,all of these
For an incompressible fluid, the __________ is a function of both pressure as well as temperature.
408,all of these
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
409,0
One ton of refrigeration capacity is equivalent to the heat removal rate of
410,200 BTU/minute
What is the degree of freedom for a system comprising liquid water equilibrium with its vapour ?
411,1
Equilibrium constant of a reaction varies with the
412,temperature.
Third law of thermodynamics is concerned with the
413,value of absolute entropy.
Claude’s liquefaction process employs the cooling of gases by
414,expansion in an engine
Gibbs free energy (F) is defined as
415,F = H - TS
The expression for entropy change given by, ΔS = nR ln (V2/V1) + nCv ln (T2/T1) is valid for
416,simultaneous heating and expansion of an ideal gas.
The second law of thermodynamics states that
417,it is not possible to transfer heat from a lower temperature to a higher temperature.
Internal energy of an ideal gas
418,none of these.
A refrigerator works on the principle of __________ law of thermodynamics.
419,second
Pick out the wrong statement.
420,With increase in temperature, the equilibrium constant increases for an exothermic reaction.
Pick out the wrong statement.
421,Enthalpies of all elements in their standard states are assumed to be zero.
Which of the following is affected by the temperature ?
422,all of these
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
423,A . X2^2
The adiabatic throttling process of a perfect gas is one of constant enthalpy
424,in which there is a temperature drop.
For spontaneous changes in an isolated system (S = entropy)
425,ds > 0
A gas performs the maximum work, when it expands
426,isothermally
There is a change in __________ during the phase transition.
427,all a, b & c
Which of the following is Virial equation of state?
428,PV = A + B/V + C/V^2 + D/V^3 + …
Pressure-enthalpy chart is useful in refrigeration. The change in internal energy of an ideal fluid used in ideal refrigeration cycle is
429,zero
First law of thermodynamics deals with the
430,none of these.
Henry’s law is closely obeyed by a gas, when its __________ is extremely high.
431,pressure
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
432,the distribution law.
A solid is transformed into vapour without going to the liquid phase at
433,triple point
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
434,5
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
435,174 K
For a thermodynamic system containing ‘x’ chemical species, the maximum number of phases that can co-exist at equilibrium is
436,x + 2
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
437,temperature, pressure, liquid composition xi and vapour composition yi.
Standard temperature and pressure (S.T.P.) is
438,0°C and 750 mm Hg
Normal temperature and pressure (N.T.P.) corresponds to
439,0°C and 760 mm Hg.
The minimum number of phases that can exist in a system is
440,1
Enthalpy changes over a constant pressure path are always zero for __________ gas.
441,a perfect
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
442,called Lewis-Randall rule
__________ does not change during phase transformation processes like sublimation, melting & vaporisation.
443,Gibbs free energy
Which one is true for a throttling process ?
444,A gas may have more than one inversion temperatures.
Choose the condition that must be specified in order to liquify CO2 (triple point for CO2 is - 57°C and 5.2 atm).
445,Pressure and temperature must be kept below 5.2 atm. and - 57°C respectively.
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
446,10373
Lenz’s law results from the law of conservation of
447,energy
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.
448,polytropic
Throttling process is a/an __________ process.
449,irreversible and constant enthalpy
The main feature of Carnot refrigeration cycle is that, it
450,accomplishes the reverse effect of the heat engine.
Charles’ law for gases states that
451,V ∞ 1/T
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.
452,-55.2
Helmholtz free energy (A) is defined as
453,A = E - TS
As pressure approaches zero, the ratio of fugacity to pressure (f/P) for a gas approaches
454,unity
For any system, what is the minimum number of degrees of freedom?
455,0
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
456,1.9398
The variation of heat of reaction with temperature at constant pressure is given by the __________ law.
457,Kirchoffs
At absolute zero temperature, the __________ of the gas is zero.
458,none of these
Which of the following equations is used for the prediction of activity co-efficient from experiments ?
459,all of these
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.
460,Gibbs-Duhem-Margules
Entropy of a substance remains constant during a/an __________ change.
461,reversible adiabatic
Gases are cooled in Joule-Thomson expansion, when it is __________ inversion temperature.
462,below
PVy = constant, holds good for an isentropic process, which is
463,reversible and adiabatic.
Which of the following behaves most closely like an ideal gas ?
464,He
In the reaction, C + O2 → CO2 ; ΔH = - 94 kcal. What is the heat content (enthalpy)of O2?
465,zero
When a system is in equilibrium for all possible processes, the differential or finite change of entropy is
466,0
A system is said to be at equilibrium, if the entropy of the system has reached __________ value.
467,maximum
In the equation, PV^n = constant, if the value of n = ± ∞, then it represents a reversible __________ process.
468,isometric
Degree of freedom of the system ice-water-vapour will be
469,1
A system in which there is exchange of energy but not of mass, is called a/an __________ system.
470,closed
The point at which all the three (solid, liquid and gas) phases co-exist, is known as the __________ point.
471,triple
In an ideal gas mixture, fugacity of a species is equal to its
472,partial pressure
The third law of thermodynamics states that the
473,heat capacity of a crystalline solid is zero at absolute zero temperature.
Consider the reaction, C + O2 ⇌ CO2 ;ΔH = - 94 kcal. What will be the value of ΔH for the reaction CO2 C + O2 ?
474,+ 94 kcal
Which is not a state function ?
475,Work
For an ideal liquid solution, which of the following is unity ?
476,Activity co-efficient
In the decomposition of PCl5 represented by, PCl5 ⇌ PCl3 + Cl2, decrease in the pressure of the system will __________ the degree of dissociation of PCl5.
477,increase
To obtain integrated form of Clausius-Clayperon equation,(1), from the exact Clayperon equafion, it is assumed that the
478,all of these.
In case of an __________ process, the temperature of the system increases.
479,adiabatic compression
Cp of a gas at its critical temperature and pressure
480,becomes infinity.
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 )
481,λb/Tb
Which of the following is true for Virial equation of state ?
482,Virial co-efficients are function of temperature only.
Molar heat capacity of water in equilibrium with ice at constant pressure is __________ Kcal/kg mole . °K
483,∞
A gas can be liquified by pressure alone only, when its temperature is __________ its critical temperature.
484,less than or equal to
For an ideal gas, the internal energy depends upon its __________ only.
485,temperature
Compound having large heat of formation is
486,more stable.
Second law of thermodynamics is concerned with the
487,direction of energy transfer.
