Process and Solution Thermodynamics Flashcards
Concepts and calculation techniques necessary for thermodynamic analyses of processes and mixtures; physical chemistry concepts are also included.
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 low 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
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 ?
Carnot refrigeration cycle.
In a working refrigerator, the value of COP is always
> 1
A refrigerator may be termed as a
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.
increases
Which of the following is not an intensive property ?
Heat capacity
Out of the following refrigration cycles, which one has the minimum COP (Co-efficient of performance)?
Air cycle
Measurement of thermodynamic property of temperature is facilitated by ____ law of thermodynamics.
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
-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.
327
Isobaric process means a constant process.
pressure
No work is done by the system, when a reaction occurs at constant
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
Clayperon-Claussius equation
The freezing point of a liquid decreases when the pressure is increased, if the liquid ____ while freezing.
contracts
At the absolute zero temperature, the entropy of every perfectly crystalline substance becomes zero. This follows from the
third law of thermodynamics
During Joule-Thomson expansion of gases
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
< 1
Degress of freedom at triple point will be
0
Law of corresponding states says that
, two different gases behave similarly, if their reduced properties (i.e. P, V and T) are same.
Linde gas liquefaction process employs cooling
by throttling
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
Boyle’s law for gases states that
(1) , when temperature & mass of the gas remain constant.
1st law of thermodynamics is nothing but the law of conservation of
energy
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).
all of these
Out of the following refrigeration cycles, which one has maximum COP ?
Carnot cycle
Pick out the correct statement:
Under reversible conditions, the adiabatic work is less than isothermal work.
In any spontaneous process,
both F and A decreases
Which of the following is a thermodynamic property of a system ?
Entropy
Equilibrium constant decreases as the temperature
increases, for an exothermic reaction.
The expression, (1) , gives the free energy change
with pressure changes at constant temperature.
All gases during throttling process at atmospheric temperature and pressure show a cooling effect except
H2
Compressibility factor for almost all the gases are approximately same at the same
reduced pressure and reduced temperature.
Pick out the wrong statement.
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.
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
all of these
In jet refrigerators, the refrigerating fluid is practically always
water
Water on heating from 1 to 4°C
contracts
Pick out the correct statement.
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
more water will be formed.
Partial molar free energy of an element A in solution is same as its
chemical potential
Free energy change at equilibrium is
zero
The temperature at which both liquid and gas phases are identical, is called the ____ point.
critical
What is the value of ln y (where y = activity co-efficient) for ideal gases ?
Zero
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
Which is not a refrigerant ?
C2H4Cl2
The partial pressure of each constituent present in an alloy is ____ the total vapor pressure exerted by the alloy.
less than
The four properties of a system viz. P, V, T, S are related by ____ equation.
Maxwell’s
If the pressure on 100 c.c. of air is halved, then its volume (at the same temperature) would be ____ c.c.
200
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.
The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are
one
Any substance above its critical temperature exists as
gas
Which of the following decreases with increase in pressure ?
Melting point of ice
Isentropic process means a constant ____ process.
entropy .
(1) is the mathematical expression
co-efficient of thermal expansion.
In case of steady flow compression polytropic process (PVn = constant), the work done on air is the lowest, when
n = 1
A liquid under pressure greater than its vapour pressure for the temperature involved is called a ____ liquid.
subcooled
For a real gas, the chemical potential is given by
RT dlnf
At absolute zero temperature, all substances have the same
heat capacity
Lowering of condenser temperature (keeping the evaporator temperature constant) in case of vapour compression refrigeration system results in
increased COP.
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.
Grams of butane (C4H10) formed by the liquefaction of 448 litres of the gas (measured at (STP) would be
1160
The thermodynamic law, PVy = constant, is not applicable in case of
free expansion of an ideal gas.
Mollier diagram is a plot of
entropy vs. enthalpy
is the mathematical expression for
none of these
The activity of an ideal gas is numerically ____ its pressure.
equal to
Specific heat of a gas for a reversible adiabatic process is
zero
When a gas in a vessel expands, its internal energy decreases. The process involved is
reversible
A system is said to be isopiestic, if there is no ____ change.
pressure
In a turbine, the fluid expands almost
adiabatically
The unity of Planck’s constant ‘h’ in the equation, E = hv is
J.S
Specific/molar Gibbs free energy for a pure substance does not change during
a. sublimation
b. vaporisation
c. melting
either (a), (b) or (c)
Refrigeration capacity of a household refrigerator may be round about ____ tons.
0.15
(1) is the mathematical expression for
none of these
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
In polytropic process (PVn = constant), if n = 1; it means a/an ____ process.
isothermal
The melting point of paraffin wax (which contracts on solidification) ____ with pressure rise.
increases
Co-efficient of Performance (COP) of a refrigerator is the ratio of the
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
0
dW and dq are not the exact differential, because q and W are
path functions
Activity co-efficient is a measure of the
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
constant
Which of the following units is not present in both the vapor compression refrigeration system and absorption refrigeration system ?
Compressor
For an isothermal reversible compression of an ideal gas
ΔE = ΔH = 0
Melting of ice exemplifies a/an
endothermic reaction.
A refrigeration cycle is the same as a ____ cycle,
reversed heat engine
At ____ point, all the three phases (i.e.solid, liquid and gas) co-exist.
triple
Kopp’s rule is used to calculate the heat capacity of
solids
____ explains the equilibrium constant for any chemical reaction.
Law of mass action
Which of the following is not a reversible process ?
Solution of NaCl in water at 50°C.
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 characterise an individual, whereas macro-state is used to designate a group of micro-states with common characteristics.
none of the above.
Which of the following exemplifies an adiabatic process ?
Sudden bursting of a cycle tube.
Entropy, which is a measure of the disorder of a system is
zero at absolute zero temperature for a perfect crystalline substance.
Critical temperature is defined as the temperature above which a gas will
never liquify however high the pressure may be.
The standard Gibbs free energy change of a reaction depends on the equilibrium
temperature
Gibbs-Duhem equation relates composition in liquid phase and the ____ at constant temperature & pressure.
a. fugacity
b. partial pressure
c. activity co-efficient
(a), (b), and (c)
In an ideal solution, the activity of a component equals its
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.
28.3
Clayperon equation deals with the
rate of change of vapour pressure with temperature.
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.
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.
What is the ratio of adiabatic compressibility to isothermal compressibility ?
< 1
The absolute entropy for all crystalline substances at absolute zero temperature is
zero
Pick out the wrong statement.
Heat and work are both state function.
Compressibility factor of a gas is
unity, if it follows PV = nRT.
Which of the following is not an extensive property ?
Refractive index
Forward reaction will be favoured for the exothermic reaction, represented by CO + H2O ⇌ CO2 + H2, by
low temperature and high pressure.
Enthalpy of a gas depends upon its
temperature
When dilute aqueous solutions of two salts are mixed, the process is associated with
increase in temperature.
Pick out the correct statement.
Maximum work is done under reversible conditions.
Chemical engineering thermodynamics is concerned with the ____ in/of chemical processes.
energy transformation from one form to the another
An isolated system can exchange ____ with its surroundings.
neither matter nor energy
Requisites of a reversible process is that the
friction in the system should be absent.
Fugacity is most helpful in
representing actual behaviour of real gases.
The energy of activation of exothermic reaction is
not possible to predict.
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.
In the reaction; N2 + O2 (1) 2NO, increasing the pressure will result in
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
349
Pick out the wrong statement.
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
energy spent in doing work.
Joule-Thomson effect i.e., a throttling process is a constant ____ process.
enthalpy
In the equation, PV^n = Constant, if the value of n = 0, then it represents a reversible ____ process.
isobaric
Work done in an adiabatic process between two states depends on the
end states only
The number of degree of freedom for an azeotropic mixture of ethanol and water in vapour-liquid equilibrium, is
1
The internal energy of an ideal gas is a function of its ____ only.
temperature
At constant temperature and pressure, for one mole of a pure substance, the ratio of the free energy to the chemical potential is
one
The change in ____ is equal to the reversible work for compression in steady state flow process under isothermal condition.
Gibbs free energy
Work done is a
path function
Extensive properties of a thermodynamic system depend upon the ____ of the system.
mass
Near their critical temperatures, all gases occupy volumes ____ that of the ideal gas.
less than
The free energy change for a chemical reaction is given by (where, K = equilibrium constant)
-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.
increases
In the reaction, H2 +I2 ⇌ 2HI, addition of an inert gas will
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 ?
2
The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called the ____ temperature.
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
remain unaltered
All gases above its inversion temperature, in a throttling process will show
a heating effect.
First law of thermodynamics is mathematically stated as
dQ = dE + dW
Pick out the wrong statement.
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 )
T
Equation which relates pressure, volume and temperature of a gas is called the
equation of state
Claussius-Clayperon equation gives accurate result, when the
a. vapour pressure is relatively low and the temperature does not vary over wide limits.
b. vapour obeys the ideal gas law and the latent heat of vaporisation is constant.
c. volume in the liquid state is negligible compared with that in the vapour state.
all of these
The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called ____ temperature.
Boyle
For a single component two phase mixture, the number of independent variable properties are
one
____ law of thermodynamics ascertains the direction of a particular spontaneous process.
Second
At normal boiling point, molar entropy of vaporisation is ____ Joule/K°.mole.
92
For an ideal solution, the value of activity co-efficient is
1
The expression, nCv(T2 - T1), is for the ____ of an ideal gas.
work done under adiabatic condition
Which of the following is a widely used refrigerant in vapour compression refrigeration system (using large centrifugal compressor)?
Freon
Internal energy is equal to the heat absorbed in case of a/an ____ process.
constant volume
The first law of thermodynamics is a restatement of the law of conservation of
mass
Joule-Thomson co-efficient for a perfect gas is
positive
In an adiabatic process, the
heat transfer is zero.
A nozzle is a device, which
increases kinetic energy and decreases pressure.
Duringthe phase transition, ____ changes.
volume
The work done in an adiabatic change in a particular gas depends upon changes in the ____ only.
temperature
In an isothermal process on an ideal gas, the pressure increases by 0.5 percent. The volume decreases by about ____ percent.
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)
(atm)Δx2, when Δx > 0
Pick out the correct statement.
all of these
Partial molal quantities are important in the study of
non-ideal mixtures
Number of degrees of freedom for a three phase system in equilibrium comprising of three non-reacting chemical species is
2
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.
Enthalpy ‘H’ is defined as
H - E = PV
One ton of refrigeration is defined as the heat rate corresponding to melting of one ton of ice in one
day
____ functions are exemplified by heat and work.
Path
In an irreversible process
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 ?
1
The entropy change in a reversible isothermal process, when an ideal gas expands to four times its initial volume is
R loge 4
PVγ = Constant (where, γ = Cp/Cv) is valid for a/an ____ process.
adiabatic
Claude gas liquefaction process employs cooling
by expansion in an engine.
Which of the following will increase the volume of a real gas by four times ?
Reducing pressure to one fourth at constant temperature.
Pick out the wrong statement.
A refriferation cycle violates the second law of thermadynamics.
The equation, PV = nRT, is best obeyed by gases at
low pressure & high temperature.
Internal energy of an element at 1 atm and 25° C is ____ kcal/kg.mole.
0
Which of the following liquid metals has the highest thermal conductivity ?
Molten sodium
Which of the following has the least thermal efficiency ?
Steam engine
Joule-Thomson Co-efficient at any point on the inversion curve is
0
Pick out the wrong statement.
Thermal efficiency of a Carnot engine depends upon the properties of the working fluid besides the source & sink temperatures.
Number of components (C), phase (P) and degrees of freedom (F) are related by Gibbs phase rule as
P + F - C = 2
The value of Cp & Cv respectively for monoatomic gases in Kcal/kg Mole . °K are
5 & 3
(1) is the mathematical expression for
Joule-Thompson co-efficient.
In case of a close thermodynamic system, there is ____ across the boundaries.
no mass transfer but heat transfer
During a reversible isothermal expansion of an ideal gas, the entropy change is
NAME?
As the temperature is lowered towards the absolute zero, the value of (1), then approaches
zero
Which of the following is not affected by temperature changes ?
None of these
For an ideal gas, the activity co-efficient is
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.
ideal
Generation of heat by friction is an example of a/an ____ change.
irreversible
A domestic refrigerator has a/an ____ cooled condenser.
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 )
V1/V2
If we increase the pressure on a substance (which is at its triple point), then the triple point
remains unchanged
In an ideal refrigeration cycle, the change in internal energy of the fluid is
0
Free energy
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.
Hess’s
Fugacity is a measure of the
escaping tendencies of the same substance in different phases of a system.
The quantitative effect of temperature on chemical equilibrium is given by the
Vant-Hoff equation.
For an irreversible process involving only pressure-volume work
(dF)T, p <0
Ideal refrigeration cycle is
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
320, 000 kW
The enthalpy change when ammonia gas is dissolved in water is called the heat of
solution
The value of Joule-Thomson co-efficient, in case where cooling occurs after the throttling process is
NAME?
The specific heat of saturated water vapour at 100°C is
-ve
For a multicomponent system, the term chemical potential is equivalent to the
partial molar free energy.
The change in Gibbs freee energy for vaporisation of a pure substance is
zero
Critical compressibility factor for all substances
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 ?
2
For a given substance at a specified temperature, activity is ____ to fugacity.
directly proportional
In case of vapour compression refrigeration system, elevating the evaporator temperature (keeping the condenser temperature constant) results in
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
6753.5
As the temperature is lowered towards the absolute zero, the value of the quantity approaches
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
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
0
The Carnot co-efficient of performance (COP) of a domestic air conditioner compared to a household refrigerator is
less
The unit of fugacity is the same as that of the
pressure
Filling of gas from a high pressure cylinder into small bottles is an example of a/an ____ process.
unsteady
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.
At the critical point of a substance
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)
Δ S1 is always > Δ SR
What is the value of Joule-Thomson co-efficient for an ideal gas ?
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)
geometric
y = specific heat ratio of an ideal gas is equal to
all of these
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.
Gibbs free energy of a pure fluid approaches ____ as the pressure tends to zero at constant temperature.
minus infinity
As the entropy of the universe is increasing, day by day, the work producing capacity of a heat engine is
decreasing
An irreversible process
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.
isothermal
Free energy change of mixing two liquid substances is a function of the
all of these
Pick out the wrong statement.
none of these
The total change in the enthalpy of a system is independent of the
number of intermediate chemical reactions involved.
Number of phases in a colloidal system are
2
Free energy changes for two reaction mechanism ‘X’ and ‘Y are respectively - 15 and - 5 units. It implies that X is
faster than Y
Vapour which is at a pressure smaller than the saturation pressure for the temperature involved is called a ____ vapour.
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.)
μ° + RT ln f
The kinetic energy of gas molecule is zero at
-273°C
Which of the following is not an intensive property ?
Volume
The necessary and sufficient condition for equilibrium between two phases is
the chemical potential of each component should be same in the two phases.
Specific volume of an ideal gas is
the reciprocal of its density.
Pick out the extensive property out of the following.
Free energy
Entropy change of the reaction, H2O(liquid) H2O(gas), is termed as the enthalpy of
vaporisation
Which law of the thermodynamics provids basis for measuring the thermodynamic property ?
Zeroth law
Gibbs free energy per mole for a pure substance is equal to the
chemical potential
Gibbs free energy at constant pressure and temperature under equilibrium conditions is
minimum
With increase in pressure (above atmospheric pressure), the Cp of a gas
increases
A change in state involving a decrease in entropy can be spontaneous, only if
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
0
____ calorimeter is normally used for measuring the dryness fraction of steam, when it is very low.
A combination of separating & throttling
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
For a constant volume process
dE = CvdT
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.
In any spontaneous process, the ____ free energy decreases.
both a & b
The equation DU = Tds - PdV is applicable to infinitesimal changes occuring in
a closed system with changes in composition.
Heat is added at constant temperature in an ideal ____ cycle.
Stirling
Pick out the correct equation relating ‘F’ and ‘A’.
F = A + PV
In a reversible process
Tds = dE + dW
Cv for an ideal gas
is independent of both pressure and volume.
In a homogeneous solution, the activity co-efficient of a component depends upon the
all of these
Pick out the wrong statement:
An isometric process is a constant pressure process.
With increase in compression ratio, the efficiency of the otto engine
increases
The chemical potential of any constituent of an ideal solution depends on the ____ of the solution.
a. temperature
b. pressure
c. composition
all of these
Fugacity and pressure are numerically equal, when the gas is
in ideal state
Refrigerants commonly used for domestic refrigerators are
ethyl chloride or methyle chloride
Absolute zero temperature signifies the
temperature of the heat reservoir to which a Carnot engine rejects no heat.
Specific ____ does not change during a phase change (e.g. sublimation, melting, vaporisation etc.).
Gibbs free energy
Heat of formation of an element in its standard state is
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
thermodynamic equation of state.
For an exothremic reaction
both ΔH and ΔE are negative.
Pick out the wrong statement.
none of these.
The shape of T-S diagram for Carnot Cycle is a
rectangle
For an isothermal process, the internal energy of a gas
remains unchanged
In the equation, PVn = constant, if the value of n = 1, then it represents a reversible ____ process.
isothermal
For the gaseous phase chemical reaction, C2H4(g) + H2O(g) ⇌ C2H5OH(g), the equilibrium conversion does not depend on the
none of these.
The first law of thermodynamics is a statement of conservation of
energy
Dry ice is
solid carbon dioxide
Which of the following non-flow reversible compression processes require maximum work ?
Adiabatic process
Pick out the correct statement.
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
Le-Chatelier principle.
Sound waves propagation in air exemplifies an ____ process.
adiabatic
For equilibrium process (i.e. reversible) in an isolated system
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
T and P
With increase in reduced temperature, the fugacity co-efficient of a gas at constant reduced pressure
increases
For an ideal gas, the enthalpy
is independent of pressure.
Efficiency of a heat engine working on Carnot cycle between two temperature levels depends upon the
two temperatures only.
In Joule-Thomson porous plug experiment, the
enthalpy does not remain constant.
A Carnot cycle consists of the following steps :
Two isothermals and two isentropics.
For a cyclic process, a fixed ratio between heat and work
always exists
Which of the following is not a common refrigerant ?
Ethylene
The most important application of distribution law is in
liquid extraction
Pick out the correct statement.
All the natural processes are reversible in nature.
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
Gibbs free energy of mixing at constant pressure and temperature is always
- ve
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
If two gases have same reduced temperature and reduced pressure, then they will have the same
none of these
Which of the following is an extensive property of a system ?
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
1
Cp - Cv = R is valid for ____ gases.
ideal
At a given temperature, the volume of a gas dissolved in a solvent ____ with increase in pressure.
remains unchanged
Which is an example of closed system ?
Lquid cooling system of an automobile
Melting of wax is accompanied with ____ in entropy.
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
ACBDA
Work done in case of free expansion is
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
1
During adiabatic expansion of gas
none of these.
Which of the following has the minimum value of COP for a given refrigeration effect?
Air refrigeration cycle.
____ decreases during adiabatic throttling of a perfect gas.
Pressure
Pick out the wrong statement.
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
increase
Change of heat content when one mole of compound is burnt in oxygen at constant pressure is called the
heat of combustion
Clausius - Clayperon equation is applicable to ____ equilibrium processes.
all of these
solid-vapor, solid-liquid?, liquid-vapor
In which of the following reaction equilibria, the value of equilibrium constant Kp will be more than is Kc ?
N2O4 ⇌ 2NO2
After throttling, gas temperature
decreases
The chemical potential for a pure substance is ____ its partial molal free energy.
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
same in both the phases.
COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about
3.5
The number of degrees of freedom for a mixture of ice and water (liquid) are
1
On opening the door of an operating refrigerator kept in a closed room, the temperature of the room will
increase
Domestic refrigerator usually works on the ____ refrigeration cycle.
absorption
Gibbs-Duhem equation
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
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
temperature
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
The internal energy of an ideal gas does not change in a reversible ____ process.
isothermal
A/an ____ system is exemplified by a vessel containing a volatile liquid in contact with its vapor.
open
In a P-V diagram (for an ideal gas), an isothermal curve will coincide withan adiabatic curve (through a point), when
Cp = Cv
For an ideal gas, the chemical potential is given by
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
same
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.
Entropy change for an irreversible isolated system is
> 0
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
The unit of equilibrium constant of a chemical reaction is the same as that of
none of these
Which of the following equations is obtained on combining 1st and 2nd law of thermodynamics, for a system of constant mass?
dE = Tds - PdV
The Joule-Thomson co-efficient is defined as (∂T/∂P)H. Its value at the inversion point is
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.
increases
Entropy is a/an
none of these
At triple point (for one component system), vapour pressure of solid as compared to that of liquid will be
same
4 kg moles of an ideal gas expands in vacuum spontaneously. The work done is
0
Which of the following is not correct for a reversible adiabatic process ?
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
T1/(T1-T2)
Throttling (Joule-Thomson effect) process is a constant ____ process.
enthalpy
Boiling of liquid is accompanied with increase in the
vapor pressure.
Change of state namely evaportation condensation, freezing and melting is an ____ process.
isothermal
Which of the following is not an equation of state?
Clausius Clayperon equation
A gas shows deviation from ideal behaviour at
low temperature and high pressure.
The difference between isothermal compressibility and adiabatic compressibility for an ideal gas is
NAME?
The expression for entropy change given by, ΔS = - nR ln (P2/P1), holds good for
reversible isothermal volume change.
With increase in temperature, the internal energy of a substance
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.
The amount of work needed is path dependent.
For a constant pressure reversible process, the enthalpy change (ΔH) of the system is
integ Cv.dT
The work done in isothermal compression compared to that in adiabatic compression will be
more
For organic compounds, group contribution method can be used for the estimation of
critical properties.
Specific ____ does not change during phase change at constant temperature and pressure.
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
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
transition
What happens in a reversible adiabatic compression ?
Heating occurs
Sublimation temperature of dry ice (solid CO2) is ____ °C.
-78
If atmospheric temperature and dew point are nearly equal, then the relative humidity is
almost 100%
Entropy change in case of reversible adiabatic process is
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
same
The efficiency of an Otto engine compared to that of a diesel engine, for the same compression ratio will be
more
Mollier chart is a ____ plot.
enthalpy vs entropy
Variation of equilibrium pressure with temperature for any two phases of a given substances is given by the ____ equation.
Clayperon
Pick out the undesirable property for a good refrigerant.
high viscosity
Isotherm on an enthalpy-concentration diagram, for an ideal solution will be a
straight line
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.
Melting of ice is an example of an ____ process.
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.
448
Rotary lime kiln is an example of a/an ____ system.
open
Heat of reaction is
dependent on both pressure and temperature.
The expression, , is for the____of an ideal gas.
work done under isothermal condition
What happens in a reversible adiabatic expansion process ?
Cooling takes place.
Degree of freedom of a system consisting of a gaseous mixture of H2 and NH3 will be
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)
(∂P/∂V)S = y(∂P/∂V)T
Pick out the wrong statement.
The entropy of the universe tends to a maximum.
Fugacity co-efficient of a substance is the ratio of its fugacity to
activity co-efficient
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
As the time is passing, entropy of the universe
is increasing
Which of the following processes can not be made reversible even under ideal condition of operation?
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.
Gibbs-Duhem
Which of the following identities can be most easily used to verify steam table data for superheated steam.
(∂V/∂T)P = -(∂S/∂P)T
In the equation PVn = constant, if the value of n = y = Cp/Cv, then it represents a reversible ____ process.
isentropic
The ammonia synthesis reaction represented by N2 + 3H2 ⇌ 2NH3 ; ΔH = - 22.4 kcal, is
exothermic
With increase in temperature, the atomic heat capacities of all solid elements
increases
The temperature at the eutectic point of the system is the ____ temperature that can be attained in the system.
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
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
superheated vapour.
An isentropic process is carried out at constant
volume
All gases except ____ shows a cooling effect during throttling process at atmospheric temperature and pressure.
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:
Δ H ≠ 0 and ΔS = 0.
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.
Compressibility factor-reduced pressure plot on reduced co-ordinates facilitates
use of only one graph for all gases.
Which of the following is not an intensive property ?
Internal energy
Pick out the wrong statement.
At constant pressure, solubility of a gas in a liquid diminishes with rise in temperature.
Gibbs phase rule finds application, when heat transfer occurs by
condensation
Absorption/evolution of heat during conversion of a substance from one allotropic form to another is termed as the heat of
transition
Ideal gas law is applicable at
high T, low P
Reduced pressure of a gas is the ratio of its
pressure to critical pressure.
For a reversible process involving only pressure-volume work
(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
300(32/7)
Entropy change for an irreversible process taking system and surrounding together is
> 0
In a homogeneous solution, the fugacity of a component depends upon the
all of these
For an incompressible fluid, the ____ is a function of both pressure as well as temperature.
enthalpy
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
One ton of refrigeration capacity is equivalent to the heat removal rate of
200 BTU/minute
What is the degree of freedom for a system comprising liquid water equilibrium with its vapour ?
1
Equilibrium constant of a reaction varies with the
temperature.
Third law of thermodynamics is concerned with the
value of absolute entropy.
Claude’s liquefaction process employs the cooling of gases by
expansion in an engine
Gibbs free energy (F) is defined as
F = H - TS
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.
The second law of thermodynamics states that
none of the above.
Internal energy of an ideal gas
none of these.
A refrigerator works on the principle of ____ law of thermodynamics.
second
Pick out the wrong statement.
With increase in temperature, the equilibrium constant increases for an exothermic reaction.
Pick out the wrong statement.
Claussius-clayperon equation is not applicable to melting process.
Which of the following is affected by the temperature ?
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
A . X2^2
The adiabatic throttling process of a perfect gas is one of constant enthalpy
which can be performed in a pipe with a constriction.
For spontaneous changes in an isolated system (S = entropy)
ds > 0
A gas performs the maximum work, when it expands
isobarically
There is a change in ____ during the phase transition.
volume
Which of the following is Virial equation of state?
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
zero
First law of thermodynamics deals with the
direction of energy transfer.
Henry’s law is closely obeyed by a gas, when its ____ is extremely high.
none of these
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.
A solid is transformed into vapour without going to the liquid phase at
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
3
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
For a thermodynamic system containing ‘x’ chemical species, the maximum number of phases that can co-exist at equilibrium is
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
temperature, pressure and liquid composition xi only.
Standard temperature and pressure (S.T.P.) is
0°C and 750 mm Hg
Normal temperature and pressure (N.T.P.) corresponds to
20°C and 760 mm Hg.
The minimum number of phases that can exist in a system is
1
Enthalpy changes over a constant pressure path are always zero for ____ gas.
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
called Lewis-Randall rule
____ does not change during phase transformation processes like sublimation, melting & vaporisation.
Gibbs free energy
Which one is true for a throttling process ?
The inversion temperature is different for different gases.
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.
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
Lenz’s law results from the law of conservation of
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.
polytropic
Throttling process is a/an ____ process.
irreversible and constant enthalpy
The main feature of Carnot refrigeration cycle is that, it
accomplishes the reverse effect of the heat engine.
Charles’ law for gases states that
V/2 = Constant
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
Helmholtz free energy (A) is defined as
A = E - TS
As pressure approaches zero, the ratio of fugacity to pressure (f/P) for a gas approaches
unity
For any system, what is the minimum number of degrees of freedom?
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
1.572
The variation of heat of reaction with temperature at constant pressure is given by the ____ law.
Kirchoffs
At absolute zero temperature, the ____ of the gas is zero.
volume
Which of the following equations is used for the prediction of activity co-efficient from experiments ?
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.
Gibbs-Duhem-Margules
Entropy of a substance remains constant during a/an ____ change.
reversible adiabatic
Gases are cooled in Joule-Thomson expansion, when it is ____ inversion temperature.
below
PVy = constant, holds good for an isentropic process, which is
reversible and adiabatic.
Which of the following behaves most closely like an ideal gas ?
He
In the reaction, C + O2 → CO2 ; ΔH = - 94 kcal. What is the heat content (enthalpy)of O2?
zero
When a system is in equilibrium for all possible processes, the differential or finite change of entropy is
< 0
A system is said to be at equilibrium, if the entropy of the system has reached ____ value.
maximum
In the equation, PV^n = constant, if the value of n = ± ∞, then it represents a reversible ____ process.
isometric
Degree of freedom of the system ice-water-vapour will be
0
A system in which there is exchange of energy but not of mass, is called a/an ____ system.
closed
The point at which all the three (solid, liquid and gas) phases co-exist, is known as the ____ point.
triple
In an ideal gas mixture, fugacity of a species is equal to its
partial pressure
The third law of thermodynamics states that the
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 ?
ERROR!
Which is not a state function ?
Work
For an ideal liquid solution, which of the following is unity ?
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.
increase
To obtain integrated form of Clausius-Clayperon equation,(1), from the exact Clayperon equafion, it is assumed that the
all of these.
In case of an ____ process, the temperature of the system increases.
adiabatic compression
Cp of a gas at its critical temperature and pressure
equals 1 kcal/kmol °K.
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
Which of the following is true for Virial equation of state ?
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
∞
A gas can be liquified by pressure alone only, when its temperature is ____ its critical temperature.
less than or equal to
For an ideal gas, the internal energy depends upon its ____ only.
temperature
Compound having large heat of formation is
more stable.
Second law of thermodynamics is concerned with the
direction of energy transfer.
