Adsorption Hierarchy (particle size order): "True is tiny (less than one), Colloid's middle (one to thousand), Suspensions settle (more than one-thousand)"

• True solution: < 1 nm
• Colloid: 1–1000 nm
• Suspension: > 1000 nm

Freundlich 1/n Rule: "Zero to one, the isotherm's done — beyond that range, use another name." 1/n must lie between 0 and 1 for the Freundlich isotherm to be valid.

Lyophilic Examples (SGPG): "Starch and Gelatin, Proteins and Gum — all love water, they're never numb." Starch, Gelatin, Proteins, Gum arabic = lyophilic (water-loving, stable, reversible)

Lyophobic Examples (GAF): "Gold, Arsenic sulfide, Fe(OH){3} — all hate water, unstable, see?" Gold sol, $As_{2}S_{3}$ sol, Fe(OH){3} sol = lyophobic (water-hating, unstable, irreversible)

Industrial Catalysts: "Haber-Fe, Contact-V, Ostwald-Pt"

• Haber ($N_{2}$ + $H_{2}$ → $NH_{3}$): Fe catalyst
• Contact ($SO_{2}$ → $SO_{3}$): $V_{2}O_{5}$ catalyst
• Ostwald ($NH_{3}$ → NO): Pt catalyst