Second law of thermodynamics Knowledge-Based Download PDF

Questions

1. 1.

   According to the second law of thermodynamics, which of the following statements correctly describes an idealized reversible process?

   • A) The entropy of the system and the entropy of the surroundings must both remain zero throughout the process.
   • B) The entropy of the system must decrease whenever spontaneous work is performed by the surroundings.
   • C) The entropy change of the system is equal in magnitude and opposite in sign to the entropy change of the surroundings.
   • D) The entropy of the universe must increase because all thermodynamic processes generate net disorder.
2. 2.

   According to the Kelvin-Planck statement of the second law of thermodynamics, which of the following is physically impossible for a system operating in a thermodynamic cycle?

   • A) Absorbing heat from a single thermal reservoir and converting it entirely into work
   • B) Converting mechanical work entirely into thermal energy through dissipative friction
   • C) Absorbing heat from a hotter reservoir, performing work, and discharging waste heat to a colder reservoir
   • D) Transferring thermal energy from a colder reservoir to a hotter reservoir using external work
3. 3.

   According to the second law of thermodynamics, which of the following conditions characterizes an isolated system that has reached thermodynamic equilibrium?

   • A) Its internal energy reaches zero as all internal molecular motion ceases.
   • B) Its entropy continually fluctuates around the absolute minimum possible value.
   • C) Its enthalpy decreases spontaneously to compensate for internal heat dissipation.
   • D) Its entropy reaches a maximum value, and no further net change in entropy can occur.
4. 4.

   According to the second law of thermodynamics, why does thermal energy flow spontaneously from a hotter object to a colder object rather than in the reverse direction?

   • A) The entropy gained by the colder object is greater in magnitude than the entropy lost by the hotter object, resulting in a net increase in total entropy.
   • B) The total thermal energy of the two interacting objects increases only when heat moves toward the object with the lower temperature.
   • C) Energy conservation inherently prohibits any heat from leaving a cooler substance under any thermodynamic conditions.
   • D) The colder object undergoes a negative entropy change that stabilizes the internal bond energies of both objects.
5. 5.

   According to the second law of thermodynamics, which statement correctly describes the entropy change that must accompany any spontaneous process?

   • A) The total entropy of the universe must increase, such that $\Delta S_{\text{univ}} = \Delta S_{\text{sys}} + \Delta S_{\text{surr}} > 0$.
   • B) The entropy of the system itself must always increase, requiring $\Delta S_{\text{sys}} > 0$ for the change to occur.
   • C) The entropy change of the surroundings must exactly balance that of the system, resulting in $\Delta S_{\text{univ}} = 0$.
   • D) The total energy of the universe must decrease to allow a net increase in molecular disorder.