Question EXE.2.HL.TZ0.12
| Date | Example questions Example questions | Marks available | [Maximum mark: 8] | Reference code | EXE.2.HL.TZ0.12 |
| Level | HL | Paper | 2 | Time zone | TZ0 |
| Command term | Calculate, Comment, Explain, State | Question number | 12 | Adapted from | N/A |
An isolated system consists of six particles. The total energy of the system is 6E, where E is a constant. The particles can randomly exchange energy between one another, in integer multiples of E.
State what is meant by an isolated system.
[1]
Neither mass nor energy is exchanged with the surroundings ✓
The energy diagram shows two possible configurations of the system. Each dot in the diagram represents one particle. In configuration A, one particle has energy 6E and the remaining particles have zero energy. In configuration B, three particles have energies 3E, 2E and E, and the remaining particles have zero energy.
State and explain the number of microstates of the system in configuration A.
[2]
6 microstates ✓
Any of the six particles can be the one of the highest energy ✓
Configuration B has 120 microstates. Calculate the entropy difference between configurations B and A. State the answer in terms of .
[2]
✓
✓
The system is initially in configuration A. Comment, with reference to the second law of thermodynamics and your answer in (c), on the likely evolution of the system.
[3]
The second law predicts that isolated systems spontaneously evolve towards high-entropy states ✓
From (c), the entropy of B is greater than that of A ✓
The final state will likely be similar to B / contain relatively many low-energy particles «of different energies» ✓