Regardless of whether a liquid-liquid binary solution behaves ideally or exhibits profound non-ideal — Solutions and Colligative Properties Chemistry Question
Question
Regardless of whether a liquid-liquid binary solution behaves ideally or exhibits profound non-ideal characteristics (positive or negative deviation), which of the following thermodynamic parameters remain universally true for the spontaneous mixing process at a constant temperature and pressure?
💡 Solution & Explanation
Mixing of two distinct pure components is inherently a spontaneous process, so the Gibbs free energy of mixing must be negative ($\Delta G_{mix} < 0$). Similarly, the disorder/randomness always increases upon mixing two different substances, so entropy must increase ($\Delta S_{mix} > 0$). $\Delta H_{mix}$ and $\Delta V_{mix}$ are strictly zero only for ideal solutions.