Freezing point depression
Dissolving a solute in a solvent lowers its freezing point. This is why salt is spread on icy roads and antifreeze is added to car radiators.
ΔTf = i · Kf · m
The new freezing point = Normal FP − ΔTf
Real-world applications
- Road salt: NaCl (i≈2) lowers water's freezing point to about −9°C at 1.5 mol/kg
- Antifreeze: Ethylene glycol (i=1) can depress freezing point to −40°C
- Seawater: Freezes at about −1.9°C due to dissolved salts