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 25 of 30
- A. Enthalpy
- B. Internal energy
- C. Gibbs free energy
- D. Entropy
Explanation: At equilibrium during a phase change, the molar Gibbs free energies of the two phases are equal, so the specific Gibbs free energy does…
Correct answer: Gibbs free energy- A. Decreases
- B. Increases
- C. Remains unchanged
- D. Increases linearly
Explanation: For chemically similar liquids, increasing molecular weight usually strengthens intermolecular attractions and reduces the tendency of…
Correct answer: Decreases- A. Both A. & B.
- B. Temperature
- C. Pressure
- D. Neither A. nor B.
Explanation: The heat of reaction generally varies with temperature through the heat-capacity change and can also vary with pressure for non-ideal…
Correct answer: Both A. & B.- A. Higher than
- B. Lower than
- C. Equal to
- D. Either A. or B.; depends on the liquids
Explanation: Immiscible liquids boil when the sum of their vapour pressures reaches atmospheric pressure.
Correct answer: Lower than- A. 3
- B. < 3
- C. > 3
- D. < 1
Explanation: A monatomic ideal gas has only three translational degrees of freedom, giving Cv = 3 cal per g-mol·K approximately.
Correct answer: > 3- A. Dilute
- B. Ideal
- C. Saturated
- D. Isotonic
Explanation: Solutions with equal osmotic pressure at the same temperature are isotonic.
Correct answer: Isotonic- A. Activity co-efficient
- B. Fugacity co-efficient
- C. Use of equation of state
- D. None of these
Explanation: Gas-phase nonideality is represented using an equation of state or a fugacity coefficient.
Correct answer: Activity co-efficient- A. Less
- B. Same
- C. More
- D. Either A. or B.; depends on the nature of the substance
Explanation: At the melting point, solid and liquid coexist in equilibrium, so their fugacities and vapour pressures are equal.
Correct answer: Same- A. Sizes of the component molecules are approximately equal
- B. All A., B. & C.
- C. Component molecules are non-polar and no chemical combination or molecular association
- D. between unlike molecules takes place in the formation of the solution
- E. Attractive forces between like and unlike molecules are approximately equal
Explanation: Raoult's law describes an ideal solution, in which like and unlike molecular attractions are nearly equal and the components have similar…
Correct answer: All A., B. & C.- A. All A., B. & C.
- B. Molal latent heat of vaporisation is constant within the limited temperature range
- C. Volume in the liquid state is negligible compared with that in the vapor state
- D. Vapor follows the ideal gas law
Explanation: The integrated Clausius-Clapeyron form assumes ideal-gas vapour behaviour, negligible liquid molar volume and nearly constant latent heat…
Correct answer: All A., B. & C.- A. Integral
- B. Both A. & B.
- C. Differential
- D. Neither A. nor B.
Explanation: Integral heat of solution refers to the total heat effect at a specified composition, while differential heat refers to the effect of…
Correct answer: Both A. & B.- A. PV = RT + B/V + y/V2 + ....
- B. (P + a/V2)(V-b) = RT
- C. loge (p/p0) = (λ/R) (1/T0 - 1/T)
- D. p = [RT/(V - b)] - (a/TV2)
Explanation: The integrated Clausius-Clapeyron equation relates vapour pressures at two temperatures through latent heat, giving ln(p/p0) = (λ/R)(1/T0…
Correct answer: loge (p/p0) = (λ/R) (1/T0 - 1/T)- A. CS2 > H2O > C2H5OH
- B. CS2 > C2H5OH > H2O
- C. H2O > CS2 > C2H5OH
- D. H2O > C2H5OH > CS2
Explanation: A larger heat of vaporisation generally indicates stronger intermolecular attraction because more energy is needed to separate the…
Correct answer: H2O > C2H5OH > CS2- A. Gaseous
- B. Unsaturated
- C. Saturated
- D. Sub-cooled
Explanation: Above the critical temperature, a substance cannot exist as a liquid-vapour saturation mixture, regardless of pressure.
Correct answer: Gaseous- A. Decreasing its temperature
- B. Increasing the volume of the vessel containing the solution
- C. None of these
- D. Diluting the solution
Explanation: Osmotic pressure follows π = iCRT, so it increases with temperature or concentration.
Correct answer: None of these- A. 2
- B. 1
- C. unpredictable
- D. 3
Explanation: At a binary eutectic point, two solid phases coexist with the liquid phase in equilibrium. Hence, three phases are present.
Correct answer: 3- A. Decreases
- B. Increases
- C. Remains unchanged
- D. Approach zero at 0°C
Explanation: The heat capacity of a solid generally falls as temperature decreases because fewer lattice vibrational modes are excited.
Correct answer: Decreases- A. Condense
- B. Both A. & B.
- C. Form wet steam
- D. Neither A. nor B.
Explanation: A saturated vapor is already at the vapor-liquid equilibrium condition, so compression at the same temperature raises its pressure above…
Correct answer: Both A. & B.499. With rise in temperature, the solubility of ammonia in water at a fixed pressure__________________?
- A. Increases
- B. Decreases
- C. Remains unchanged
- D. Increases exponentially
Explanation: Ammonia dissolves in water with the release of heat, so increasing temperature shifts the equilibrium toward ammonia leaving the liquid.
Correct answer: Decreases- A. Molal heat capacities of gases
- B. Heat capacities of gases
- C. Activation energy
- D. Heat capacities of solids
Explanation: Kopp's rule estimates the heat capacity of a solid compound by adding the approximate atomic heat capacities of its constituent elements.
Correct answer: Heat capacities of solids