Free Chemical Engineering Thermodynamics MCQs with Answers
598 Chemical Engineering Thermodynamics MCQs from Chemical Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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598 questions · page 7 of 30
- A. Pressure
- B. Temperature
- C. Volume
- D. All A , B. and C
Explanation: During a phase change, latent heat changes the molecular arrangement and usually produces a change in specific volume, while temperature…
Correct answer: Volume- A. Solid-vapor
- B. Solid-liquid
- C. Liquid-vapor
- D. All A, B. and C
Explanation: The Clausius-Clapeyron relation describes the slope of any phase-equilibrium curve, including solid-vapor, solid-liquid, and liquid-vapor…
Correct answer: All A, B. and C- A. Maxwell's
- B. Gibbs-Helmholtz
- C. Gibbs-Duhem
- D. None of these
Explanation: Maxwell relations connect changes in P, V, T, and S by equating mixed second derivatives of thermodynamic potentials.
Correct answer: Maxwell's- A. √T
- B. T
- C. T2
- D. 1/√T
Explanation: The average translational kinetic energy of ideal-gas molecules is proportional to absolute temperature, as given by the molecular…
Correct answer: T- A. 4 J
- B. ∞
- C. 0
- D. 8 J
Explanation: During free expansion into a vacuum, there is no opposing external pressure, so boundary work W = bf PfdV is zero.
Correct answer: 0- A. Either A, B. or C.
- B. Vaporisation
- C. Melting
- D. Sublimation
Explanation: At equilibrium, the molar Gibbs free energy, or chemical potential, is identical in the phases of a pure substance.
Correct answer: Either A, B. or C.- A. Reverse Carnot cycle
- B. Air refrigeration cycle
- C. Vapour-compression process with a reversible expansion engine
- D. Ordinary vapour-compression cycle
Explanation: The reverse Carnot cycle gives the maximum COP between specified temperature limits, while regenerative or reversible expansion improves…
Correct answer: Air refrigeration cycle- A. Fugacity
- B. Activity
- C. Chemical potential
- D. Activity co-efficient
Explanation: Chemical potential is defined as the partial molar Gibbs free energy, bcA = (bG/bnA) at fixed temperature, pressure, and other…
Correct answer: Chemical potential- A. Low pressure and high temperature
- B. Low pressure and low temperature
- C. High temperature and high pressure
- D. Low temperature and high pressure
Explanation: Non-ideal behaviour becomes most noticeable when molecules are close together and intermolecular forces matter, as at high pressure and…
Correct answer: Low temperature and high pressure- 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
Explanation: For Helmholtz free energy, dA = -S dT - P dV; equality of the mixed second derivatives gives (∂S/∂V)T = (∂P/∂T)V.
Correct answer: (∂S/∂V)T = (∂P/∂T)V- A. Zero
- B. Negative
- C. Infinity
- D. None of these
Explanation: For a reversible adiabatic process, δQ = 0, so the path heat capacity defined by C = δQ/dT is zero.
Correct answer: Zero- A. Greater than
- B. Less than
- C. The same
- D. Different than
Explanation: Decomposition and formation are reverse processes, so their heats have equal magnitude and opposite signs.
Correct answer: The same- A. RT d ln P
- B. R d ln P
- C. R d ln f
- D. None of these
Explanation: At constant temperature, the chemical-potential change is dμ = RT d ln f; for an ideal gas, fugacity f equals pressure P.
Correct answer: RT d ln P- A. Free expansion of an ideal gas
- B. Ideal compression of air
- C. Adiabatic expansion of steam in a turbine
- D. Adiabatic compression of a perfect gas
Explanation: The relation PVᵞ = constant describes a reversible adiabatic process for an ideal gas.
Correct answer: Free expansion of an ideal gas- A. Increase
- B. Remain unaltered
- C. Decrease
- D. Increase or decrease; depends on the particular reaction
Explanation: Kirchhoff's relation is d(ΔH)/dT = ΔCp. If the total heat capacities of products and reactants are identical, ΔCp is zero and the heat of…
Correct answer: Remain unaltered- A. Property of the system
- B. Point function
- C. Path function
- D. State description of a system
Explanation: Work depends on the process path followed between two states, so it is a path function rather than a property or point function.
Correct answer: Path function- A. ∫ Cp.dT
- B. Cp.dT
- C. Cv.dT
- D. ∫ Cv.dT
Explanation: At constant pressure, the enthalpy change is obtained by integrating the heat-capacity relation, ΔH = ∫Cp dT.
Correct answer: ∫ Cp.dT- A. Equilibrium cannot be established
- B. More ice will be formed
- C. More water will be formed
- D. Evaporation of water will take place
Explanation: Ice occupies more volume than the same mass of water, so increasing pressure favors the lower-volume phase, water.
Correct answer: More water will be formed- A. T2/R1
- B. T2/(T1-T2)
- C. T1/T2
- D. T1/(T1-T2)
Explanation: A Carnot heat pump delivers heat Q1 to the high-temperature reservoir, and its work input is Q1 − Q2.
Correct answer: T1/(T1-T2)- A. Temperature
- B. Specific heat
- C. Volume
- D. Pressure
Explanation: For an adiabatic change of an ideal gas, Q = 0 and the work is related to the internal-energy change, W = nCv(T1−T2) for work done by the…
Correct answer: Temperature