Colligative Properties

Card 1
Q: What are colligative properties?
A: Properties that depend only on the number of solute particles in solution, not their identity.

Card 2
Q: What are the four colligative properties?
A:

1. Vapor pressure lowering

2. Boiling point elevation

3. Freezing point depression

4. Osmotic pressure

Card 3
Q: What is vapor pressure lowering?
A: The vapor pressure of a solution is lower than that of the pure solvent due to fewer solvent molecules at the surface.

Card 4
Q: What is Raoult's Law?
A: Psolution=Xsolvent⋅Psolvent∘Psolution​=Xsolvent​⋅Psolvent∘​, where XX is the mole fraction and P∘P∘ is vapor pressure of pure solvent.

Card 5
Q: What is boiling point elevation?
A: The boiling point of a solution is higher than that of the pure solvent.

Card 6
Q: Formula for boiling point elevation?
A: ΔTb=i⋅Kb⋅mΔTb​=i⋅Kb​⋅m

• ΔTbΔTb​ = increase in boiling point

• ii = van’t Hoff factor

• KbKb​ = ebullioscopic constant

• mm = molality

Card 7
Q: What is freezing point depression?
A: The freezing point of a solution is lower than that of the pure solvent.

Card 8
Q: Formula for freezing point depression?
A: ΔTf=i⋅Kf⋅mΔTf​=i⋅Kf​⋅m

• ΔTfΔTf​ = decrease in freezing point

• ii = van’t Hoff factor

• KfKf​ = cryoscopic constant

• mm = molality

Card 9
Q: What is osmotic pressure?
A: The pressure needed to stop the flow of solvent through a semipermeable membrane into a more concentrated solution.

Card 10
Q: Formula for osmotic pressure?
A: Π=i⋅M⋅R⋅TΠ=i⋅M⋅R⋅T

• ΠΠ = osmotic pressure

• ii = van’t Hoff factor

• MM = molarity

• RR = gas constant

• TT = temperature in Kelvin

Card 11
Q: What is the van’t Hoff factor (i)?
A: The number of particles the solute breaks into in solution (e.g., NaCl → 2, CaCl₂ → 3).

Card 1
Q: What happens to osmotic pressure when more solute is added to a solution?
A: Osmotic pressure increases, because more solute increases concentration → Π=iMRTΠ=iMRT

Card 2
Q: What happens to the boiling point when more solute is added to a solution?
A: Boiling point increases (not decreases) due to boiling point elevation → ΔTb=iKbmΔTb​=iKb​m

Card 3
Q: What happens to the vapor pressure when more solute is added to a volatile solvent?
A: Vapor pressure decreases, since solute particles block evaporation → Raoult’s Law

Card 4
Q: True or False: Adding solute lowers the boiling point of a solution.
A: False. It raises the boiling point.

Card 5
Q: True or False: Adding solute lowers the vapor pressure of a solution.
A: True. Vapor pressure goes down as solute is added.

Card 6
Q: True or False: Adding solute increases osmotic pressure.
A: True. Higher solute concentration = higher osmotic pressure.