hce_nthu
111年
化學與物理
第 1 題
1. One mole of an ideal gas undergoes an isothermal reversible expansion at 300 K. During this process, the system absorbs 450 J of heat from the surroundings. When this gas is compressed to the initial state in one step isothermally, twice as much work is done on the system as was performed on the surroundings during the expansion. Which of the following statements about these processes are correct?
I. $\Delta S_{\text{sys}}$ for the one-step isothermal compression is $1.5\text{ J/K}$.
II. $\Delta S_{\text{surr}}$ for the one-step isothermal compression is $3.0\text{ J/K}$.
III. $\Delta S_{\text{univ}}$ for the reversible isothermal expansion is zero.
IV. $\Delta S_{\text{univ}}$ for the overall process (expansion and compression) is zero.
V. $\Delta S_{\text{surr}}$ for the overall process (expansion and compression) is $-1.5\text{ J/K}$.
I. $\Delta S_{\text{sys}}$ for the one-step isothermal compression is $1.5\text{ J/K}$.
II. $\Delta S_{\text{surr}}$ for the one-step isothermal compression is $3.0\text{ J/K}$.
III. $\Delta S_{\text{univ}}$ for the reversible isothermal expansion is zero.
IV. $\Delta S_{\text{univ}}$ for the overall process (expansion and compression) is zero.
V. $\Delta S_{\text{surr}}$ for the overall process (expansion and compression) is $-1.5\text{ J/K}$.
- A I, II
- B II, III
- C II, III, IV
- D II, III, V
- E I, IV, V
思路引導 VIP
如果在一個等溫循環過程中，系統最終回到了完全相同的初始狀態，那麼「系統本身」的熵變化量（State Function）理論上應該是多少？接著請思考，如果其中一個步驟是「不可逆」的（例如單一步驟快速壓縮），這對「環境」所造成的熱交換與熵改變，會跟原先的可逆路徑相同嗎？
🤖
AI 詳解
AI 專屬家教
恭喜你準確地掌握了熱力學中**熵（Entropy）與可逆性（Reversibility）**的核心關聯！這道題目能判斷正確，代表你對於系統與環境在不同路徑下的能量交換有著非常細緻的理解。
核心觀念解析
在 300 K 的等溫可逆膨脹中，根據定義，可逆過程的宇宙總熵變化量 $\Delta S_{\text{univ}}$ 必然為零（敘述 III 正確）。此時系統吸收 450 J 的熱量，系統熵增 $\Delta S_{\text{sys}} = \frac{450}{300} = 1.5 \text{ J/K}$，而環境則相應地減少了 $1.5 \text{ J/K}$。
▼ 還有更多解析內容