The standard thermodynamic derivation of the freezing point depression equation rests on several fun — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

The $\Delta T_f$ equation is strictly valid only for dilute, ideal solutions (B). It specifically assumes that the solid phase precipitating out is purely the solvent, leaving all solute in the remaining liquid (C). The derivation also assumes that the enthalpy of fusion ($\Delta H_f$) does not change noticeably over the small temperature drop $\Delta T_f$ (D). Highly concentrated solutions deviate from ideality, making A completely false.