entropy concept

Question

Which process has ΔS > 0 at constant temperature?

RankGuru · Accepted Answer

1. **Entropy ($S$)**: A measure of the randomness or disorder of a system.
2. **Dissolution Process**: When solid $NaCl$ dissolves, the highly ordered crystal lattice breaks down, and ions ($Na^+, Cl^-$) disperse into the solvent. This significantly **increases randomness**.
3. **Analysis of others**:
   - **Condensation**: Gas $	o$ Liquid (Order increases, $\Delta S < 0$).
   - **Freezing**: Liquid $	o$ Solid (Order increases, $\Delta S < 0$).
   - **Solid formation**: Ions $	o$ Solid (Order increases, $\Delta S < 0$).
4. **Conclusion**: Only the **dissolution of NaCl** results in a positive entropy change ($\Delta S > 0$).

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entropy concept

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