Process and Solution Thermodynamics (Archived) Flashcards
(This deck is archived.) Concepts and calculation techniques necessary for thermodynamic analyses of processes and mixtures; physical chemistry concepts are also included.
Sublimation temperature of dry ice (solid CO2) is
___°C.
-78
The equation relating E, P, V, and T which is true for all substances under all conditions is given by (𝜕E/𝜕V)T = T(𝜕P/𝜕T)H - P. This equation is called the ____.
a. Maxwell Equation
b. Thermodynamic Equation of State
c. Equation of State
d. Redlich-Kwong Equation of State
Thermodynamic Equation of State
Henry’s law is closely obeyed by a gas, when its ____ is extremely high.
a. Pressure
b. Solubility
c. Temperature
d. None of these
d. None of these
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 and B
d. Neither A nor B
Both A and B
The ammonia synthesis reaction represented by N2 + 3 H2 ↔ 2 NH3; ∆H = −22.4 kcal is
a. Endothermic
b. Exothermic
c. Isothermal
d. Adiabatic
Exothermic
Free energy changes for two reaction mechanism ‘X’ and ‘Y’ are respectively -15 and -5 units. It implies that X is
Faster than Y
Which of the following has the minimum value of COP for a given refrigeration effect?
a. Reverse Carnot Cycle
b. Ordinary Vapour-Compression Cycle
c. Vapor-compression process with a reversible
expansion engine
d. Air refrigeration cycle
Air refrigeration cycle
No work is done by the system, when a reaction occurs at constant
a. Volume
b. Temperature
c. Pressure
d. None of these
Volume
In the reaction, H2 + I2 ↔ 2HI, addition of an inert gas will
Not affect the equilibrium conditions
The work done in isothermal compression compared to that in adiabatic compression will be
More
What happens in a reversible adiabatic expansion process?
Cooling takes place
Which of the following is affected by the temperature?
a. Fugacity
b. Activity coefficient
c. Free energy
d. All of the above
All of the above
Which is an example of closed system?
a. Air compressor
b. Liquid cooling system of an automobile
c. Boiler
d. None of these
Liquid cooling system of an automobile
Entropy of an ideal gas depends upon its
a. Pressure
b. Temperature
c. Both A and B
d. Neither A nor B
Both A and B
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).
a. µ° + RT ln f
b. µ° + R ln f
c. µ° + T ln f
d. µ° + (R/T) ln f
µ° + RT ln f
Partial molal quantities are important in the study of
a. Ideal gases
b. Ideal solutions
c. Non-ideal mixtures
d. A pure component
Non-ideal mixtures
For organic compounds, group condition method can be used for the estimation of
a. Critical properties
b. Specific gravity
c. Specific volume
d. Thermal conductivity
Critical properties
The efficiency of a Carnot heat engine operating between absolute temperatures T1 and T2 (where, T1>T2) is given by (T1-T2)/T1. The coefficient of performance (COP) of a Carnot heat pump operating between T1 and T2 is given by
a. T1/(T1-T2)
b. T2/(T1-T2)
c. T1/T2
d. T2/T1
T1/(T1-T2)
Internal energy of an element at 1 atm and 25°C is ____ kcal/kg-mole.
0
At the critical point of a substance
a. The surface tension vanishes
b. Liquid and vapour have the same density
c. There is no distinction between liquid and vapour phases
d. All of the above
All of the above
In a P-V diagram (for an ideal gas), an isothermal curve will coincide with an adiabatic curve (through a point), when
a. Cp < Cv
b. Cp = Cv
c. Cp > Cv
d. Cp ≥ Cv
Cp = Cv
The shape of T-S diagram for Carnot Cycle is a
a. Rectangle
b. Rhombus
c. Trapezoid
d. Circle
Rectangle
With increase in compression ratio, the efficiency of
the otto engine
a. Increases
b. Decreases
c. Remains constant
d. Increases linearly
Increases
η = 1 - 1/r^(k-1)
What is the degree of freedom for a system comprising liquid water equilibrium with its vapour?
1
df = N (component) - π (phase) - r (reaction) + 2
____ functions are exemplified by heat and work.
a. Path
b. Point
c. State
d. None of these
Path
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 the P1 and P2 (where, P1 and P2 are initial and final pressures respectively.
a. Logarithmic
b. Arithmetic
c. Geometric
d. Harmonic
geometric
Helmholtz free energy (A) is defined as
a. A = H − TS
b. A = E − TS
c. A = H + TS
d. None of these
A = E - TS
E is usually U (internal energy)
Gibbs free energy (F) is defined as
a. F = E − TS
b. F = H − TS
c. F = H + TS
d. F = E + TS
F = H - TS
F is usually G (Gibbs energy)
A system is said to be at equilibrium if the entropy of the system has reached ____ value.
Maximum
In the reaction, C + O2 → CO2; ∆H = −94 kcal. What is the heat content (enthalpy) of O2?
Zero
The Maxwell relation derived from the differential expression for the Helmholtz free energy (dA) is
a. (∂T/∂V)S = - (∂P/∂S)V
b. (∂S/∂P)T = - (∂V/∂T)P
c. (∂V/∂S)P = (∂T/∂P)S
d. (∂S/∂V)T = (∂P/∂T)V
(∂S/∂V)T = (∂P/∂T)V
Which of the following processes can not be made reversible even under ideal condition of operation?
a. Free expansion of a gas
b. Compression of air in a compressor
c. Expansion of steam in a turbine
d. All of the above
Free expansion of a gas
Heat is added at constant pressure in an ideal ____ cycle.
a. Stirling
b. Brayton
c. Rankine
d. Both B and C
Both B and C
Heat is added at constant temperature in an ideal ____ cycle.
a. Stirling
b. Brayton
c. Rankine
d. Both B and C
Stirling
The standard state of a gas (at a given temperature) is the state in which fugacity is equal to
a. Unity
b. Activity
c. Both A and B
d. Neither A nor B
Both A and B
For a constant volume process ____ by the system is used only to increase the internal energy.
a. Heat absorbed
b. Work done
c. Both A and B
d. Neither A nor B
Heat absorbed
Which of the following is not a common refrigerant?
a. Freon-12
b. Ethylene
c. Ammonia
d. Carbon Dioxide
Ethylene
Which of the following is not a reversible process?
a. Expansion of an ideal gas against constant pressure
b. Atmospheric pressure vaporization of water at 100°C
c. Solution of NaCl in water at 50°C
d. None of these
Solution of NaCl in water at 50°C
For spontaneous changes in an isolated system (S = entropy)
a. Ds = 0
b. Ds < 0
c. Ds > 0
d. Ds = constant
dS > 0
A gas performs the maximum work, when it expands
a. Non-uniformly
b. Adiabatically
c. Isobarically
d. Isothermally
Isobarically
Degree of freedom of a system consisting of a gaseous mixture of H2 and NH3 will be
3
df = N - π - r + 2
A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system
a. Its internal energy (U) decreases and its entropy (S) increases
b. U and S both decreases
c. U decreases but S is constant
d. U is constant but S decreases
U and S both decreases
The expression for entropy change given by, ∆S = −nR ln P2/P1, holds good for
a. Expansion of a real gas
b. Reversible isothermal volume change
c. Heating of an ideal gas
d. Cooling of a real gas
Reversible isothermal volume change
For any system, what is the minimum number of degrees of freedom?
0
Which of the following is not a unit of the equilibrium constant Kp? (where, ∆x = number of moles of products - number of moles of reactants)
a. (atm)^∆x, when ∆x is negative
b. (atm)^∆x, when ∆x is positive
c. Dimensionless, when ∆x = 0
d. (atm)^∆(x²), when ∆x > 0
(atm)^∆(x²), when ∆x > 0
Equilibrium constant of a reaction varies with the
a. Initial concentration of the reactant
b. Pressure
c. Temperature
d. None of these
Temperature
Which of the following will increase the volume of a real gas by four times?
a. Doubling the absolute temperature as well as pressure of the gas
b. Reducing pressure to one fourth at constant temperature
c. Reducing temperature to one fourth at constant pressure
d. Reducing the temperature to half and doubling the pressure
Reducing pressure to one fourth at constant temperature
The eccentric factor of a material, ‘ω’ is defined as ω = − log10(Pr^sat)Tr^-1 − 1 = 0.7, where Pr^sat = reduced vapor pressure, Tr = reduced temperature. The value of accentric factor is always
< 1
The number of degrees of freedom for a mixture of ice and water (liquid) are
1
df = N - π - r + 2
“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 amount.” This is
the distribution law
What is the number of degrees of freedom for liquid water in equilibrium with a mixture of nitrogen and water vapor?
2
df = N - π - r + 2
The first law of thermodynamics is a restatement of the law of conservation of
Energy
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 and C
Both B and C
The second law of thermodynamics states that
a. The energy change of a system undergoing any reversible process is zero.
b. It is not possible to transfer heat from a lower temperature to a higher temperature.
c. The total energy of a system and surrounding remains the same.
d. None of the above.
None of the above.
If we increase the pressure on a substance (which is at its triple point), then the triple point
Remains unchanged
Maximum work that could be secured by expanding the gas over a given pressure range is the ____ work.
Isothermal
The fusion of a crystalline solid at its melting point to form a liquid at the same temperature is accompanied by
a. Decrease in enthalpy corresponding to evolution of heat
b. Decrease of entropy
c. Increase in enthalpy corresponding to absorption of heat
d. No change in enthalpy
Increase in enthalpy corresponding to absorption of heat
The minimum number of phases that can exist in a
system is
1
Extensive properties of a thermodynamic system can
depend upon the ____ of the system.
mass
Van Laar equation deals with the activity coefficients in
binary solutions
1m3 of an ideal gas at 500K 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/mol-K, the final temperature will be
274 K
When pressure is applied on the system, ice ↔ water, then
a. Equilibrium can not be established
b. More ice will be formed
c. More water will be formed
d. Evaporation of water will take place
More water will be formed
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
If the atmospheric temperature and dew point are nearly equal, then the relative humidity is
Almost 100%
First law of thermodynamics deals with the
Direction of energy transfer
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
COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about
3.5
The number of degree of freedom for an azeotropic mixture of ethanol and water in vapour-liquid equilibrium, is
1
Gibbs free energy of a pure fluid approaches ____ as the pressure tends to zero at constant temperature.
minus infinity
Out of the following refrigeration cycles, which one has the minimum COP (Coefficient of Performance)?
a. Air cycle
b. Carnot cycle
c. Ordinary vapour compression cycle
d. Vapour compression with a reversible expansion engine
Air cycle
At absolute zero temperature, all substances have the same
a. Heat capacity
b. Crystalline structure
c. Entropy
d. None of these
Heat capacity
The expression, ∆G = nRT ln P2/P1, gives the free energy change
a. With pressure changes at constant temperature
b. Under reversible isothermal volume change
c. During heating of an ideal gas
d. During cooling of an ideal gas
With pressure changes at constant temperature
The thermodynamic law, PV^γ = 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
Free expansion of an ideal gas
Entropy change of the reaction, H2O (liquid) → H2O (gas), is termed as the enthalpy of
vaporisation
Specific ____ does not change during a phase change (e.g., sublimation, melting, vaporization etc.).
Gibbs free energy
For an ideal gas, the activity coefficient is
unity at all pressure
For an isothermal process, the internal energy of a gas
remains unchanged
If two gases have same reduced temperature and reduced pressure, then they will have the same
a. Volume
b. Mass
c. Critical temperature
d. None of these
None of these
accentric factor could be different
Gibbs phase rules finds application when heat
transfer occurs by
condensation
There is a change in ____ during the phase transition.
a. Volume
b. Pressure
c. Temperature
d. All of the above
Volume
At a given temperature, the volume of a gas dissolved in a solvent ____ with increase in pressure.
remain unchanged
Chemical engineering thermodynamics is concerned with the ____ in/of chemical processes.
energy transformation from one form to the
another
A gas can be liquified by pressure alone only when its temperature is ____ its critical temperature.
less than or equal to
In case of a close thermodynamic system, there is ____ across the boundaries.
no mass transfer but heat transfer
Clausius – Clayperon equation is applicable to ____ equilibrium processes.
a. Solid-vapor
b. Solid-liquid
c. Liquid-vapor
d. All of the above
All of the above
However, SLE is not applicable due to small volume changes.
In any spontaneous process, the ____ free energy decreases.
Both Helmholtz and Gibbs
Gases are cooled in Joule-Thomson expansion, when it is ____ inversion temperature.
below
Fundamental principle of refrigeration is based on the ____ law of thermodynamics.
Second
Measurement of thermodynamic property of temperature is facilitated by ____ law of thermodynamics.
Zeroth
A refrigerator works on the principle of ____ law of
thermodynamics.
Second
Near their critical temperature, all gases occupy volumes ____ that of the ideal gas
less than
An isolated system can exchange ____ with its
surroundings.
neither matter nor energy
The coefficient 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.
a. Kinematic viscosity
b. Work
c. Temperature
d. None of these
None of these
Domestic refrigerators usually work on the ____
refrigeration cycle.
absorption
At absolute zero temperature, the ____ of the gas is zero.
volume
The melting point of paraffin wax (which contracts on solidification) ____ with pressure rise.
increases
The expression for entropy change given by ∆S = nR ln(V2/V1) + nCv ln(T2/T1) is valid for
Simultaneous heating and expansion of an
ideal gas
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, γ = Cp/Cv).
a. (𝜕P/𝜕V)S = (𝜕P/𝜕V)T
b. (𝜕P/𝜕V)S = [ (𝜕P/𝜕V)T ]^γ
c. (𝜕P/𝜕V)S = γ (𝜕P/𝜕V)T
d. (𝜕P/𝜕V)S = (1/γ) (𝜕P/𝜕V)T
(𝜕P/𝜕V)S = γ (𝜕P/𝜕V)T
Trouton’s ratio is given by (where λb = molal heat of vaporization of a substance at its normal boiling point, kcal/kmol Tb = normal boiling point, °K.)
a. λb/Tb
b. Tb/λb
c. √(λb/Tb)
d. √(Tb/λb)
λb/Tb
Isentropic process means a constant ____ process.
Entropy
