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Colligative Properties
AP Chemistry · Unit 3 Intermolecular Forces
Learning Objectives
Calculate boiling point elevation (ΔTb = i·Kb·m)
Calculate freezing point depression (ΔTf = i·Kf·m)
Apply van't Hoff factor (i) for electrolytes
Predict osmotic pressure (π = iMRT)
Key Equations
ΔT
b
= i·K
b
·m
ΔT
f
= i·K
f
·m
π = iMRT
K
b
(H₂O) = 0.512 °C/m
K
f
(H₂O) = 1.86 °C/m
Tags
colligative
boiling point
freezing point
osmotic pressure
Molality (m)
1.0
van't Hoff factor (i)
1
i=1: non-electrolyte (glucose) · i=2: NaCl · i=3: CaCl₂
Boiling Point
100.51°C
ΔT
b
0.51°C
Freezing Point
-1.86°C
ΔT
f
1.86°C
π (atm)
24.5
Solute Type
Non-elec