At the same concentration, why does calcium chloride melt ice better than glucose?
Colligative effects depend on the number of dissolved particles, captured by the van't Hoff factor i.
Colligative effects depend on the number of dissolved particles, captured by the van't Hoff factor i. Glucose stays as single molecules (i = 1). CaCl₂ dissociates into three ions — one Ca²⁺ and two Cl⁻ (i ≈ 3) — so the same amount produces about three times as many particles and roughly three times the freezing-point depression. More particles, more melting power.
Key point
Effect ∝ i × concentration; CaCl₂ (i ≈ 3) beats glucose (i = 1) particle-for-particle.
Common mistake
comparing masses instead of particle counts.
Memory tip
count the ions: the more particles a solute releases, the bigger the colligative effect.
Tap to watch or see it right here — the app stays open (it only opens a quick search if nothing embeddable is found).