ChE Thermodynamics Flashcards
Maximum work that could be secured by expanding the gas over a given pressure range is the __________ work.
A. Isothermal
B. Adiabatic
C. Isentropic
D. None of these
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
A. Binary Solutions
B. Ternary Solutions
C. Azeotropic Mixtures
D. None of these
A. 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
_______ pressure and _______ temperature.
low, low
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 (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 ?
A. Vapor compression cycle using expansion valve.
B. Air refrigeration cycle.
C. Vapor compression cycle using expansion engine.
D. Carnot refrigeration cycle.
D. Carnot refrigeration cycle.
In a working refrigerator, the value of COP is always
greater than 1
__________ increases with increase in pressure.
A. Melting point of a wax
B. Boiling point of a liquid
C. Both a and b
D. None of these
C. Both a and b
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 ?
A. Chemical potential
B. Surface tension
C. Heat capacity
D. None of these
C. Heat capacity
Out of the following refrigration cycles, which one has the minimum COP (Co-efficient of performance)?
A. Air cycle
B. Carnot Cycle
C. Ordinary vapour compression cycle
D. Vapour compression with a reversible expansion engine
A. Air cycle
Measurement of thermodynamic property of temperature is facilitated by __________ law of thermodynamics.
zeroth
Entropy of an ideal gas depends upon its
A. Pressure
B. Temperature
C. Both a and b
D. None of these
C. Both a and b
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
Clausius-Clapeyron 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, ________ remains constant
Enthalpy
“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
Joule-Thomson experiment is
A. isobaric
B. Adiabatic
C. Isenthalpic
D. Both b and c
D. Both b and c
1st law of thermodynamics is nothing but the law of conservation of
Energy
Out of the following refrigeration cycles, which one has maximum COP ?
A. Air cycle
B. Carnot Cycle
C. Ordinary vapour compression cycle
D. Vapour compression with a reversible expansion engine
B. Carnot Cycle
Which of the following is a thermodynamic property of a system ?
A. Concentration
B. Mass
C. Temperature
D. Entropy
D. Entropy
Equilibrium constant decreases as the temperature _____
increases, for an exothermic reaction
All gases during throttling process at atmospheric temperature and pressure show a cooling effect except
Hydrogen gas
Compressibility factor for almost all the gases are approximately same at the same
reduced pressure and reduced temperature.
In jet refrigerators, the refrigerating fluid is practically always
water
Water on heating from 1 to 4°C
contracts
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
Heat pump
a. accomplishes only space heating in winter.
b. accomplishes only space cooling in summer.
c. accomplishes both (a) and (b).
d. works on Carnot cycle.
c. accomplishes both (a) and (b).
The temperature at which both liquid and gas phases are identical, is called the __________ point.
Critical Point
A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system, U _________ and S __________
decreases, decreases
The partial pressure of each constituent present in an alloy is __________ the total vapor pressure exerted by the alloy.
less than
Heat is added at constant pressure in an ideal __________ cycle.
A. Stirling
B. Brayton
C. Rankine
D. both (b) and (c)
D. both (b) and (c)
Entropy change of mixing two liquid substances depends upon the
A. molar concentration
B. quantity (i.e. number of moles)
C. both (a) and (b)
D. neither (a) nor (b)
C. both (a) and (b)
The four properties of a system viz. P, V, T, S are related by __________ equation.
Maxwell’s Equation
If the pressure on 100 c.c. of air is halved, then its volume (at the same temperature) would be __________ c.c.
200
The principle applied in liquefaction of gases is
A. adiabatic expansion.
B. Joule-Thomson effect.
C. both (a) and (b).
D. neither (a) nor (b).
C. both (a) and (b).
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 ?
A. Melting point of ice
B. Melting point of wax
C. Boiling point of liquids
D. none of these
A. Melting point of ice
Isentropic process means a constant __________ process.
Entropy
In case of steady flow compression polytropic process (PV^n = 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 _____ COP
increased
he thermodynamic law, PV^n = constant, is not applicable in case of
A. ideal compression of air.
B. free expansion of an ideal gas.
C. adiabatic expansion of steam in a turbine.
D. adiabatic compression of a perfect gas.
B. free expansion of an ideal gas.
Mollier diagram is a plot of
Entropy vs Enthalpy
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
D. either (a), (b) or (c)
D. either (a), (b) or (c)
Refrigeration capacity of a household refrigerator may be round about __________ tons.
0.15
Chemical potential is a/an
A. extensive property.
B. intensive property.
C. force which drives the chemical system to equilibrium.
D. both (b) and (c)
D. both (b) and (c)
In polytropic process (PV^n = 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
A. work required to refrigeration obtained.
B. refrigeration obtained to the work required.
C. lower to higher temperature.
D. higher to lower temperature.
B. refrigeration obtained to the work required.
dW and dq are not the exact differential, because q and W are
path functions
Activity co-efficient is a measure of the
A. departure from ideal solution behaviour.
B. departure of gas phase from idea] gas law.
C. vapour pressure of liquid.
D. none of these.
A. 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
Melting of ice exemplifies a/an ________ reaction
endothermic
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 exemplifies an adiabatic process?
A. Melting of ice.
B. Condensation of alcohol vapor.
C. Sudden bursting of a cycle tube.
D. Evaporation of water.
C. Sudden bursting of a cycle tube.
Entropy, which is a measure of the disorder of a system is
A. independent of pressure.
B. independent of temperature.
C. zero at absolute zero temperature for a perfect crystalline substance.
D. all (a), (b) & (c)
C. zero at absolute zero temperature for a perfect crystalline substance.
Critical temperature is defined as the temperature above which a gas will
A. not liquify (barring exceptions).
B. immediately liquify.
C. never liquify however high the pressure may be.
D. none of these.
C. 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
D. (a), (b), and (c)
D. (a), (b), and (c)
In an ideal solution, the activity of a component equals its
mole fraction
Clayperon equation deals with the
A. rate of change of vapour pressure with temperature.
B. effect of an inert gas on vapour pressure.
C. calculation of ΔF for spontaneous phase change.
D. temperature dependence of heat of phase transition.
A. rate of change of vapour pressure with temperature.
What is the ratio of adiabatic compressibility to isothermal compressibility ?
less than 1
The absolute entropy for all crystalline substances at absolute zero temperature is
zero
Which of the following is not an extensive property ?
A. Free energy
B. Entropy
C. Refractive index
D. None of these
C. Refractive index
Enthalpy of a gas depends upon its
temperature
Pick out the correct statement.
A. Like internal energy and enthalpy, the absolute value of standard entropy for elementary substances is zero.
B. Melting of ice involves increase in enthalpy and a decrease in randomness.
C. The internal energy of an ideal gas depends only on its pressure.
D. Maximum work is done under reversible conditions
D. Maximum work is done under reversible conditions
Chemical engineering thermodynamics is concerned with the __________ in/of chemical processes.
A. reaction mechanism
B. calculation of rates
C. energy transformation from one form to the another
D. none of these
C. 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
A. system and surroundings pressure be equal.
B. friction in the system should be absent.
C. system and surroundings temperature be equal.
D. none of these.
B. friction in the system should be absent.
Fugacity is most helpful in
A. representing actual behaviour of real gases.
B. representing actual behaviour of ideal gases.
C. the study of chemical equilibria involving gases at atmospheric pressure.
D. none of these
A. representing actual behaviour of real gases.
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
A. rate of heat transmission
B. initial state only
C. end states only
D. none of these
C. 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 ______ function
path
Entropy of the system decreases, when
A. snow melts into water.
B. a gas expands spontaneously from high pressure to low pressure.
C. water is converted into ice.
D. both (b) & (c).
D. both (b) & (c).
Extensive properties of a thermodynamic system depend upon the __________ of the system
mass
If an ideal solution is formed by mixing two pure liquids in any proportion, then the __________ of mixing is zero.
A. enthalpy
B. volume
C. both ‘a’ & ‘b’
D. neither ‘a’ nor ‘b’
C. both ‘a’ & ‘b’
Near their critical temperatures, all gases occupy volumes __________ that of the ideal gas.
less than
The fugacity co-efficient of a gas at constant pressure ____with the increase of reduced temperature.
increases
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
Equation which relates pressure, volume and temperature of a gas is called the
equation of state
For a single component two phase mixture, the number of independent variable properties are
1
__________ 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.
A. work done under adiabatic condition
B. co-efficient of thermal expansion
C. compressibility
D. none of these
A. work done under adiabatic condition
The number of degrees of freedom at the triple point of water is
0
Which of the following is a widely used refrigerant in vapour compression refrigeration system (using large centrifugal compressor)?
A. Freon
B. Liquid sulphur dioxide
C. Methyl chloride
D. Ammonia
A. 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
energy
Joule-Thomson co-efficient for a perfect gas is
0
In an adiabatic process, the ________ is zero
heat transfer (Q)
A nozzle is a device, which _______ kinetic energy, _________ pressure
increases, decreases
During the 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
Partial molal quantities are important in the study of
A. ideal gases
B. ideal solutions
C. non-ideal mixtures
D. a pure component
C. non-ideal mixtures
Number of degrees of freedom for a three phase system in equilibrium comprising of three non-reacting chemical species is
2
__________ functions are exemplified by heat and work.
Path
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
