Problem 11-99

The higher the number of particles in solution:

• the higher the boiling point
• the lower the freezing point (and the vapor pressure, not in SN2)

Ionic compounds (electrolyte) dissociate in several ions in solution:
Na₃PO₄ → 3 Na⁺ + PO₄³⁻ = 4 particles (i = 4)

Therefore, for each solution: c_compound x i = c_particles or molality of the particles in solution

compound	c	i	cparticles
Na3PO4	0.010 m	4	0.040 m
CaBr2	0.020 m	3	0.060 m
KCl	0.020 m	2	0.040 m
HF*	0.020 m	1	0.020 m

*HF 0.020 m particles since HF is a weak acid = not dissocialed.

Therefore:
  highest number of particles: CaBr₂
  Lowest number of particles: HF

a) Same number of particles as 0.040 m = C₆H₁₂O₆: Na₃PO₄ and KCl
b) highest vapor pressure = least particles: HF (not for SN2)
c) largest ΔT_f = Most particles: Na₃PO₄