Thermodynamics Part 2 Flashcards
Enthalpy ‘H’ is defined as
H = E - PV
H = F - TS
H - E = PV
none of these
H - E = PV
One ton of refrigeration is defined as the heat rate corresponding to melting of one ton of ice in one
hour
day
minute
second
day
__________ functions are exemplified by heat and work.
Path
Point
State
none of these
Path
In an irreversible process
Tds = dE - dW = 0
dE - dW - Tds = 0
Tds - dE + dW< 0
Tds - dT + dW< 0
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 ?
3
2
1
0
1
The entropy change in a reversible isothermal process, when an ideal gas expands to four times its initial volume is
R loge 4
R log10 4
Cv log10 4
Cv loge 4
R loge 4
PVgamma = Constant (where, gamma = Cp/Cv) is valid for a/an __________ process.
isothermal
isentropic
isobaric
adiabatic
adiabatic
Claude gas liquefaction process employs cooling
at constant pressure.
by throttling.
by expansion in an engine.
none of these.
by expansion in an engine.
Which of the following will increase the volume of a real gas by four times ?
Doubling the absolute temperature as well as pressure of the gas.
Reducing pressure to one fourth at constant temperature.
Reducing temperature to one fourth at constant pressure.
Reducing the temperature to half and doubling the pressure.
Reducing pressure to one fourth at constant temperature.
Pick out the wrong statement.
A refriferation cycle violates the second law of thermadynamics.
Refrigeration cycle is normally represented by a temperature vs. entropy plot.
In a refrigerator, work required decreases as the temperature of the refrigerator and the temperature at which heat is rejected increases.
One ton of refrigeration is equivalent to the rate of heat absorption equal to 3.53 kW.
A refriferation cycle violates the second law of thermadynamics.
The equation, PV = nRT, is best obeyed by gases at
low pressure & high temperature.
high pressure & low temperature.
low pressure & low temperature.
none of these.
low pressure & high temperature.
Internal energy of an element at 1 atm and 25 C is __________ kcal/kg.mole.
0
273
25
none of these
0
Which of the following liquid metals has the highest thermal conductivity ?
Molten sodium
Molten lead
Mercury
Molten potassium
Molten sodium
Which of the following has the least thermal efficiency ?
Steam engine
Carnot engine
Diesel engine
Otto engine
Steam engine
Joule-Thomson Co-efficient at any point on the inversion curve is
infinity
+ ve
0
-ve
0
Pick out the wrong statement.
The values of (1) are zero for a real gas at its critical point.
Heat transferred is equal to the change in the enthalpy of the system, for a constant pressure, non-flow, mechanically reversible process.
Thermal efficiency of a Carnot engine depends upon the properties of the working fluid besides the source & sink temperatures.
During a reversible adiabatic process, the entropy of a substance remains constant.
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
C = P - F + 2
F = C - P - 2
P = F - C - 2
P + F - C = 2
The value of Cp & Cv respectively for monoatomic gases in Kcal/kg Mole . K are
5 & 3
3.987 & 1.987
1.987 & 0.66
0.66 & 1.987
5 & 3
(aT/aP)H is the mathematical expression for (a = partial differential)
specific heat at constant pressure (Cp).
specific heat at constant volume (Cv).
Joule-Thompson co-efficient.
none of these.
Joule-Thompson co-efficient.
In case of a close thermodynamic system, there is __________ across the boundaries.
no heat and mass transfer
no mass transfer but heat transfer
mass and energy transfer
none of these
no mass transfer but heat transfer
During a reversible isothermal expansion of an ideal gas, the entropy change is
+ve
0
-ve
infinity
+ve
As the temperature is lowered towards the absolute zero, the value of (a(delta-F))/aT, then approaches
unity
zero
that of the heat of reaction
infinity
zero
Which of the following is not affected by temperature changes ?
Fugacity
Activity co-efficient
Free energy
None of these
None of these
For an ideal gas, the activity co-efficient is
directly proportional to pressure.
inversely proportional to pressure.
unity at all pressures.
none of these.
unity at all pressures.
ideal activity unity
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
real
isotonic
none of these
ideal
Generation of heat by friction is an example of a/an __________ change.
isothermal
irreversible
adiabatic
reversible
irreversible
A domestic refrigerator has a/an __________ cooled condenser.
water
air
evaporative
gas
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
V2/V1
V1-V2
V1.V2
V1/V2
If we increase the pressure on a substance (which is at its triple point), then the triple point
increases
decreases
remains unchanged
may increase or decrease ; depends on the substance
remains unchanged
In an ideal refrigeration cycle, the change in internal energy of the fluid is
+ve
-ve
0
either of the above three ; depends on the nature of refrigerant.
0
Free energy
decreases in all spontaneous (or irreversible) processes.
change during a spontaneous process has a negative value.
remains unchanged in reversible processes carried at constant temperature and pressure.
all of these
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
Kirchoff’s
Lavoisier and Laplace
none of these
Hess’s
Fugacity is a measure of the
escaping tendencies of the same substance in different phases of a system.
relative volatility of a mixture of two miscible liquids.
behaviour of ideal gases.
none of these.
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.
Le-Chatelier’s principle.
Arhenius equation.
none of these.
Vant-Hoff equation.
For an irreversible process involving only pressure-volume work
(dF)T, p <0
(dF)T, p = 0
(dF)T, p > 0
(dA)T, v >0
(dF)T, p <0
Ideal refrigeration cycle is
same as Carnot cycle.
same as reverse Carnot cycle.
dependent on the refrigerant’s properties.
the least efficient of all refrigeration processes.
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
100, 000 kW
160, 000 kW
200, 000 kW
320, 000 kW
320, 000 kW
The enthalpy change when ammonia gas is dissolved in water is called the heat of
solution
formation
dilution
combustion
solution
The value of Joule-Thomson co-efficient, in case where cooling occurs after the throttling process is
0
infinity
+ve
-ve
+ve
The specific heat of saturated water vapour at 100 C is
infinity
-ve
0
+ve
-ve
For a multicomponent system, the term chemical potential is equivalent to the
molal concentration difference.
molar free energy.
partial molar free energy.
molar free energy change.
partial molar free energy.
The change in Gibbs freee energy for vaporisation of a pure substance is
positive
negative
zero
may be positive or negative
zero
Critical compressibility factor for all substances
are more or less constant (vary from 0.2 to 0.3).
vary as square of the absolute temperature.
vary as square of the absolute pressure.
none of these.
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 ?
0
1
2
3
2
For a given substance at a specified temperature, activity is __________ to fugacity.
directly proportional
inversely proportional
equal
none of these
directly proportional
In case of vapour compression refrigeration system, elevating the evaporator temperature (keeping the condenser temperature constant) results in
enhanced COP.
decreased COP.
no change in the value of COP.
increased or decreased COP ; depending upon the type of refrigerant.
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
6738.9
6753.5
7058.3
9000
6753.5
As the temperature is lowered towards the absolute zero, the value of the quantity approaches
zero
unity
infinity
none of these
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 increases.
solubility increases as temperature decreases.
solubility is independent of temperature.
solubility increases or decreases with temperature depending on the Gibbs free energy change of solution.
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
1
y = 1.44
1.66
0
The Carnot co-efficient of performance (COP) of a domestic air conditioner compared to a household refrigerator is
less
more
same
dependent on climatic conditions
less
The unit of fugacity is the same as that of the
pressure
temperature
volume
molar concentration
pressure
Filling of gas from a high pressure cylinder into small bottles is an example of a/an __________ process.
equilibrium
adiabatic
steady
unsteady
unsteady
A large iceberg melts at the base, but not at the top, because of the reason that
ice at the base contains impurities which lowers its melting point.
due to the high pressure at the base, its melting point reduces.
the iceberg remains in a warmer condition at the base.
all of these
due to the high pressure at the base, its melting point reduces.
At the critical point of a substance
the surface tension vanishes.
liquid and vapour have the same density.
there is no distinction between liquid and vapour phases.
all of these
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, delta- S1 and delta- SR are the entropy changes of the system for the irreversible and reversible processes respectively)
delta- S1 is always < delta- SR
delta- S1 is sometimes > delta- SR
delta- S1 is always > delta- SR
delta- S1 is always = delta- SR
delta- S1 is always > delta- SR
What is the value of Joule-Thomson co-efficient for an ideal gas ?
+ve
-ve
0
infinity
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)
logarithmic
arithmetic
geometric
harmonic
geometric
γ = specific heat ratio of an ideal gas is equal to
Cp/Cv
Cp/(CP-R)
1 + (R/CV)
all of these
all of these
Consider the process A & B shown in the figure given below (1) In this case, it is possilbe that
both the processes are adiabatic.
both the processes are isothermal.
process A is isothermal while B is adiabatic.
process A is adiabatic while B is isothermal.
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.
infinity
minus infinity
zero
none of these
minus infinity
As the entropy of the universe is increasing, day by day, the work producing capacity of a heat engine is
not changed
decreasing
increasing
data sufficient, can’t be predicted
decreasing
An irreversible process
is the analog of linear frictionless motion in machines.
is an idealised visualisation of behaviour of a system.
yields the maximum amount of work.
yields an amount of work less than that of a reversible 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.
isobaric
isothermal
adiabatic
none of these
isothermal
Free energy change of mixing two liquid substances is a function of the
concentration of the constituents only.
quantities of the constituents only.
temperature only.
all of these
all of these
Pick out the wrong statement.
System (of partially miscible liquid pairs), in which the mutual solubility increases with rise in temperature, are said to possess an upper consolute temperature.
Systems, in which the mutual solubility increases with decrease in temperature, are said to possess lower consolute temperature.
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.
none of these
none of these
The total change in the enthalpy of a system is independent of the
number of intermediate chemical reactions involved.
pressure and temperature.
state of combination and aggregation in the beginning and at the end of the reaction.
none of these.
number of intermediate chemical reactions involved.
Number of phases in a colloidal system are
1
2
3
4
2
Free energy changes for two reaction mechanism ‘X’ and ‘Y are respectively - 15 and - 5 units. It implies that X is
slower than Y
faster than Y
three times slower than Y
three times faster than Y
faster than Y
Vapour which is at a pressure smaller than the saturation pressure for the temperature involved is called a __________ vapour.
superheated
desuperheated
non-condensable
none of these
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
μ + R lnf
μ + T lnf
μ + R/T lnf
μ + RT ln f
The kinetic energy of gas molecule is zero at
0 C
273 C
100 C
-273 C
-273 C
Which of the following is not an intensive property ?
Volume
Density
Temperature
Pressure
Volume
The necessary and sufficient condition for equilibrium between two phases is
the concentration of each component should be same in the two phases.
the temperature of each phase should be same.
the pressure should be same in the two phases.
the chemical potential of each component should be same in the two phases.
the chemical potential of each component should be same in the two phases.
Specific volume of an ideal gas is
equal to its density.
the reciprocal of its density.
proportional to pressure.
none of these.
the reciprocal of its density.
Pick out the extensive property out of the following.
Surface tension
Free energy
Specific heat
Refractive index
Free energy
Entropy change of the reaction, H2O(liquid) H2O(gas), is termed as the enthalpy of
solution
vaporisation
formation
formation
vaporisation
Which law of the thermodynamics provids basis for measuring the thermodynamic property ?
First law
Zeroth law
Third law
Second law
Zeroth law
Gibbs free energy per mole for a pure substance is equal to the
latent heat of vaporisation
chemical potential
molal boiling point
heat capacity
chemical potential
Gibbs free energy at constant pressure and temperature under equilibrium conditions is
infinity
0
maximum
minimum
minimum
With increase in pressure (above atmospheric pressure), the Cp of a gas
increases
decreases
remains unchanged
first decreases and then increases
increases
A change in state involving a decrease in entropy can be spontaneous, only if
it is exothermic.
it is isenthalpic.
it takes place isothermally.
it takes place at constant volume.
it is exothermic.
Joule-Thomson co-efficient which is defined as, n = (aT/aP)H = (1/Cp)(aH/aT)P , changes sign at a temperature known as inversion temperature. The value of Joule-Thomson co-efficient at inversion temperature is
0
infinity
+ve
-ve
0
__________ calorimeter is normally used for measuring the dryness fraction of steam, when it is very low.
Bucket
Throttling
Separating
A combination of separating & throttling
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.
less than
more than
same as
not related to
same as
For a constant volume process
dE = CpdT
dE = CvdT
dQ = dE + pdV
dW = pdV
dE = CvdT
In case of the decomposition of hydroiodic acid (2HI <~> H2 + I2), addition of H2 (at equilibrium condition) will
increase the partial pressure of I2.
decrease the partial pressure of HI.
diminish the degree of dissociation of HI.
none of these.
diminish the degree of dissociation of HI.
In any spontaneous process, the __________ free energy decreases.
Helmholtz
Gibbs
both a & b
neither ‘a’ nor ‘b’
both a & b
The equation DU = Tds - PdV is applicable to infinitesimal changes occuring in
an open system of constant composition.
a closed system of constant composition.
an open system with changes in composition.
a closed system with changes in composition.
a closed system with changes in composition.
Heat is added at constant temperature in an ideal __________ cycle.
Stirling
Brayton
Rankine
none of these
Stirling
stirling - heat added at constant temp
Pick out the correct equation relating ‘F’ and ‘A’.
F = A + PV
F = E + A
F = A - TS
F = A + TS
F = A + PV
In a reversible process
Tds = dE + dW
dE - dW = Tds
dW - dE = Tds
Tds - dW + dE >0
Tds = dE + dW
Cv for an ideal gas
does not depend upon temperature.
is independent of pressure only.
is independent of volume only.
is independent of both pressure and volume.
is independent of both pressure and volume.
In a homogeneous solution, the activity co-efficient of a component depends upon the
pressure
composition
temperature
all of these
all of these
Pick out the wrong statement:
The expansion of a gas in vacuum is an irreversible process.
An isometric process is a constant pressure process.
Entropy change for a reversible adiabatic process is zero.
Free energy change for a spontaneous process is negative.
An isometric process is a constant pressure process.
With increase in compression ratio, the efficiency of the otto engine
increases
decreases
remains constant
increases linearly
increases
The chemical potential of any constituent of an ideal solution depends on the __________ of the solution.
temperature
pressure
composition
all of these
all of these
Fugacity and pressure are numerically equal, when the gas is
in standard state
at high pressure
at low temperature
in ideal state
in ideal state
ideal - equal fugacity and pressure
Refrigerants commonly used for domestic refrigerators are
ethyl chloride or methyle chloride
freon-12
propane
NH3 or CO2.
ethyl chloride or methyle chloride
Absolute zero temperature signifies the
minimum temperature attainable.
temperature of the heat reservoir to which a Carnot engine rejects all the heat that is taken in.
temperature of the heat reservoir to which a Carnot engine rejects no heat.
none of these.
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.).
entropy
internal energy
enthalpy
Gibbs free energy
Gibbs free energy
Heat of formation of an element in its standard state is
0
< 0
> 0
a function of pressure
0
The equation relating E, P, V and T which is true for all substanes under all conditions is given by (∂E/∂V)T = T (∂P/∂T)H - P .This equation is called the
Maxwell’s equation.
thermodynamic equation of state.
equation of state.
Redlich-Kwong equation of state.
thermodynamic equation of state.
For an exothremic reaction
only enthalpy change (delta-H) is negative.
only internal energy change (delta-E) is negative.
both delta-H and delta-E are negative.
enthalpy change is zero.
both delta-H and delta-E are negative.
Pick out the wrong statement.
An ideal liquid or solid solution is defined as one in which each component obeys Raoult’s law.
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.
Henry’s law is rigorously correct in the limit of infinite dilution.
none of these.
none of these.
The shape of T-S diagram for Carnot Cycle is a
rectangle
rhombus
trapezoid
circle
rectangle
For an isothermal process, the internal energy of a gas
increases
decreases
remains unchanged
data insufficient, can’t be predicted
remains unchanged
In the equation, PVn = constant, if the value of n = 1, then it represents a reversible __________ process.
isothermal
isobaric
polytropic
adiabatic
isothermal
For the gaseous phase chemical reaction, C2H4(g) + H2O(g) <~> C2H5OH(g), the equilibrium conversion does not depend on the
steam to ethylene ratio.
temperature.
pressure.
none of these.
none of these.
The first law of thermodynamics is a statement of conservation of
heat
momentum
energy
work
energy
“Dry ice” is
moisture free ice
solid helium
solid carbon dioxide
none of these
solid carbon dioxide
Which of the following non-flow reversible compression processes require maximum work ?
Adiabatic process
Isothermal process
Isobaric process
All require same work
Adiabatic process
Pick out the correct statement.
A real gas on expansion in vacuum gets heated up.
An ideal gas on expansion in vacuum gets cooled.
An ideal gas on expansion in vacuum gets heated up.
A real gas on expansion in vacuum cools down whereas ideal gas remains unaffected.
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.
Kopp’s rule.
law of corresponding state.
Arrehenius hypothesis.
Le-Chatelier principle.
Sound waves propagation in air exemplifies an __________ process.
adiabatic
isothermal
isometric
none of these
adiabatic
For equilibrium process (i.e. reversible) in an isolated system
ds = 0
ds < 0
ds > 0
ds = Constant
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
T and P
T, P and Z
T and Z
T and P
With increase in reduced temperature, the fugacity co-efficient of a gas at constant reduced pressure
increases
decreases
remains same
decreases linearly
increases
For an ideal gas, the enthalpy
increases with rise in pressure.
decreases with rise in pressure.
is independent of pressure.
is a path function.
is independent of pressure.
Efficiency of a heat engine working on Carnot cycle between two temperature levels depends upon the
two temperatures only.
pressure of working fluid.
mass of the working fluid.
mass and pressure both of the working fluid.
two temperatures only.
In Joule-Thomson porous plug experiment, the
enthalpy does not remain constant.
entire apparatus is exposed to surroundings.
temperature remains constant.
none of these.
enthalpy does not remain constant.
A Carnot cycle consists of the following steps :
Two isothermals and two isentropics.
Two isobarics and two isothermals.
Two isochorics and two isobarics.
Two isothermals and two isochorics.
Two isothermals and two isentropics.
For a cyclic process, a fixed ratio between heat and work
always exists
may exist
never exists
is difficult to predict
always exists
Which of the following is not a common refrigerant ?
Freon-12
Ethylene
Ammonia
Carbon dioxide
Ethylene
The most important application of distribution law is in
evaporation
liquid extraction
drying
distillation
liquid extraction
Pick out the correct statement.
Entropy and enthalpy are path functions.
In a closed system, the energy can be exchanged with the surrounding, while. matter can not be exchanged.
All the natural processes are reversible in nature.
Work is a state function.
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
6.2
0.168
data insufficient, can’t be found out
5.2
Gibbs free energy of mixing at constant pressure and temperature is always
0
∞
+ve
-ve
-ve
The compressibility factor for an ideal gas is 1. Its value for any other real gas is
1
< 1
> 1
either (b) or (c), depends on the nature of the gas
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
volume
mass
critical temperature
none of these
none of these
Which of the following is an extensive property of a system ?
Heat capacity
Molal heat capacity
Pressure
Concentration
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
2
3
0
1
Cp - Cv = R is valid for __________ gases.
ideal
all
very high pressure
very low temperature
ideal
At a given temperature, the volume of a gas dissolved in a solvent __________ with increase in pressure.
increases
decreases
remains unchanged
may increase or decrease; depends on the gas
remains unchanged
Which is an example of closed system ?
Air compressor
Lquid cooling system of an automobile
Boiler
None of these
Lquid cooling system of an automobile
Melting of wax is accompanied with __________ in entropy.
increase
decrease
no change
none of these
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
P1ACBP2P1
ACBB1A1A
ACBDA
ADBB1A1A
ACBDA
Work done in case of free expansion is
indeterminate
zero
negative
none of these
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
0
1
infinity
none of these
1
During adiabatic expansion of gas
pressure remains constant.
pressure is increased.
temperature remains constant.
none of these.
none of these.
Which of the following has the minimum value of COP for a given refrigeration effect?
Reverse Carnot cycle.
Ordinary vapour-compression cycle.
Vapour-compression process with a reversible expansion engine.
Air refrigeration cycle.
Air refrigeration cycle.
__________ decreases during adiabatic throttling of a perfect gas.
Entropy
Temperature
Enthalpy
Pressure
Pressure
adibatic throttling pressure decrease
Pick out the wrong statement.
Minimum number of degree of freedom of a system is zero.
Degree of freedom of a system containing a gaseous mixture of helium, carbon dioxide and hydrogen is 4.
For a two phase system in equilibrium made up of four non-reacting chemical species, the number of degrees of freedom is 4.
Enthalpy and internal energy change is zero during phase change processes like melting, vaporisation and sublimation.
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
decrease
remain unchanged
first fall and then rise.
increase
Change of heat content when one mole of compound is burnt in oxygen at constant pressure is called the
calorific value
heat of reaction
heat of combustion
heat of formation
heat of combustion
Clausius - Clayperon equation is applicable to __________ equilibrium processes.
solid-vapor
solid-liquid
liquid-vapor
all of these
all of these
In which of the following reaction equilibria, the value of equilibrium constant Kp will be more than is Kc ?
2HI <~> H2 + I2
N2O4 <~> 2NO2
2SO2 + O2 <~> 2SO3
none of these
N2O4 <~> 2NO2
After throttling, gas temperature
decreases
increases
remains same
may increase or decrease ; depends on the nature of the gas
decreases
The chemical potential for a pure substance is __________ its partial molal free energy.
more than
less than
equal to
not related to
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.
zero in both the phases.
more in vapour phase.
more in liquid phase.
same in both the phases.
COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about
0.5
3.5
4.5
8.5
3.5
3.5 COPref 1kW
The number of degrees of freedom for a mixture of ice and water (liquid) are
2
3
1
0
1
On opening the door of an operating refrigerator kept in a closed room, the temperature of the room will
increase
decrease
remain same
increase in summer and will decrease in winter
increase
Domestic refrigerator usually works on the __________ refrigeration cycle.
Carnot
air
absorption
vapour-ejection
absorption
Gibbs-Duhem equation
states that n1du1 + n2du2 + ….njduj = 0, for a system of definite composition at constant temperature and pressure.
applies only to binary systems.
finds no application in gas-liquid equilibria involved in distillation.
none of these
states that n1du1 + n2du2 + ….njduj = 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
1
4
2
3
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
pressure
volume
temperature
all of these.
temperature
“When a gas is expanded from high pressure region to low pressure region ; temper -ature change occurs”. This phenomenon is related to the
Gibbs-Duhem equation
Gibbs-Helmholtz equation
Third law of thermodynamics
Joule-Thomson effect
Joule-Thomson effect
The internal energy of an ideal gas does not change in a reversible __________ process.
isothermal
adiabatic
isobaric
isometric
isothermal
A/an __________ system is exemplified by a vessel containing a volatile liquid in contact with its vapor.
isolated
closed
open
none of these
open
In a P-V diagram (for an ideal gas), an isothermal curve will coincide withan adiabatic curve (through a point), when
Cp < Cv
Cp = Cv
Cp > Cv
C >= Cv
Cp = Cv
For an ideal gas, the chemical potential is given by
RT dlnP
R dlnP
R dlnf
none of these
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
doubled
halved
one fourth of its original value
same
In the ammonia synthesis reaction, N2 + 3H2 <~> 2NH3 + 22.4 kcal, the formation of NH3 will be favoured by
high temperature.
low pressure.
low temperature only.
both low temperature and high pressure.
both low temperature and high pressure.
Entropy change for an irreversible isolated system is
infinity
0
< 0
> 0
> 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
less than
greater than
different than
the same
The unit of equilibrium constant of a chemical reaction is the same as that of
molar concentration
temperature
internal energy
none of these
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
dQ = CvdT + PdV
dQ = CpdT + Vdp
Tds = dE - PdV
dE = Tds - PdV
The Joule-Thomson co-efficient is defined as (aT/aP)H. Its value at the inversion point is
infinity
1
0
-ve
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.
decreases
decreases exponentially
increases
remains constant
increases
