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Entropy Knowledge-Based Practice

Chemistry · Thermochemistry & Thermodynamics · Chemistry · Entropy & Free Energy

5 Chemistry practice questions on Entropy. Questions that assess core concepts and understanding.

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Questions

  1. 1.

    For an irreversible process occurring in an isolated system, which of the following statements regarding the entropy of the system is always correct?

    • A) It remains constant because energy is conserved within the system.
    • B) It decreases because spontaneous changes minimize thermal energy.
    • C) It increases until the system achieves thermodynamic equilibrium.
    • D) It is equal to the enthalpy change divided by absolute temperature.
  2. 2.

    At constant temperature TT and constant pressure, which mathematical relationship correctly expresses the entropy change of the surroundings (ΔSsurr\Delta S_{\text{surr}}) in terms of the enthalpy change of the system (ΔHsys\Delta H_{\text{sys}})?

    • A) ΔSsurr=−ΔHsysT\Delta S_{\text{surr}} = -\frac{\Delta H_{\text{sys}}}{T}
    • B) ΔSsurr=ΔHsysT\Delta S_{\text{surr}} = \frac{\Delta H_{\text{sys}}}{T}
    • C) ΔSsurr=−TΔHsys\Delta S_{\text{surr}} = -T\Delta H_{\text{sys}}
    • D) ΔSsurr=−TΔHsys\Delta S_{\text{surr}} = -\frac{T}{\Delta H_{\text{sys}}}
  3. 3.

    In Boltzmann's statistical definition of entropy, S=kBln⁡WS = k_{\text{B}} \ln W, what does the quantity WW represent?

    • A) The reversible work done by the system during an expansion
    • B) The number of accessible microstates corresponding to the macrostate
    • C) The probability of heat exchange between the system and its surroundings
    • D) The total internal energy distributed among molecular motions
  4. 4.

    Which of the following gaseous substances has the highest standard molar entropy (S∘S^\circ) at 298 K and 1 bar?

    • A) CH4(g)CH_4(g)
    • B) C3H8(g)C_3H_8(g)
    • C) N2(g)N_2(g)
    • D) He(g)He(g)
  5. 5.

    Which of the following processes results in an increase in the entropy of the system?

    • A) Sublimation of solid carbon dioxide to form carbon dioxide gas
    • B) Condensation of water vapor into liquid water
    • C) Reaction of nitrogen gas and hydrogen gas to produce ammonia gas
    • D) Freezing of liquid ethanol into solid ethanol

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