Misconception 1: "Colligative properties depend on the type of solute"

Reality: Colligative properties depend ONLY on the NUMBER of dissolved particles. 0.1 m glucose and 0.1 m urea have identical colligative effects because both have i=1 and same molality.

Misconception 2: "Higher temperature means better gas solubility"

Reality: Temperature increase DECREASES gas solubility (K_H increases → less gas dissolves). This is opposite to most solid solutes. Only some salts (like $Na_{2}SO_{4}$) show decreased solubility above ~32°C.

Misconception 3: "Association always halves the molar mass"

Reality: Association gives a higher apparent molar mass (not lower). Dimerization gives i=0.5 → apparent M ≈ 2 × true M. Students confuse "fewer particles" with "smaller effect" and get the direction wrong.

Misconception 4: "Ideal solutions have $\Delta S$_mix = 0"

Reality: Ideal solutions have $\Delta H$_mix = 0 and $\Delta V$_mix = 0, but $\Delta S$_mix > 0 always (entropy increases on mixing). The Gibbs energy $\Delta G$_mix = −T$\Delta S$_mix < 0 for ideal mixing.

Misconception 5: "Osmotic pressure uses molality, like $\Delta Tb$ and $\Delta Tf$"

Reality: Osmotic pressure formula π = iCRT uses molarity C (mol/L), NOT molality. $\Delta Tb$ and $\Delta Tf$ use molality (mol/kg solvent). This unit distinction is a frequent NEET trap.

Misconception 6: "Maximum boiling azeotrope = positive deviation"

Reality: Reversed. Positive deviation → higher P → LOWER boiling point → MINIMUM boiling azeotrope. Negative deviation → lower P → HIGHER boiling point → MAXIMUM boiling azeotrope.

Misconception 7: "The van't Hoff factor i is always an integer"

Reality: i is non-integer for partial dissociation/association. NaCl with 80% dissociation: i = 1 + (2−1)(0.8) = 1.8. Only complete dissociation gives integer i values.

Misconception 8: "Freezing point depression and boiling point elevation use the same constant"

Reality: Kf ≠ Kb for any solvent. For water: Kf = 1.86, Kb = 0.52 (different by factor ~3.6). Always use the correct constant for the correct phenomenon.