📖 Theory & Concepts ▼

Lyophilic vs Lyophobic Sols

Lyophilic ("Solvent-loving")

Strong affinity for dispersion medium. Reversible, self-stabilizing.

Examples: Starch, Gelatin, Gum, Rubber

Lyophobic ("Solvent-hating")

No affinity for medium. Irreversible, needs stabilizers.

Examples: Metals (Au, Ag), Sulphides, Metal hydroxides

Key Properties

  • Tyndall Effect: Scattering of light by colloidal particles (1-1000 nm)
  • Brownian Motion: Zigzag movement due to molecular collisions
  • Coagulation: Precipitation by electrolytes (Hardy-Schulze rule)
Preparation Methods:

• Dispersion: Breaking large particles (peptization, mechanical, ultrasonic)

• Condensation: Building from molecules (chemical reactions, Bredig's arc)

💧

Lyophilic Sols

"Solvent-loving" • Reversible
Pure Water
Add starch or gelatin
Properties:
  • • Self-stabilizing (no stabilizer needed)
  • • High viscosity
  • • Reversible (reforms after evaporation)
  • • Weak Tyndall effect
⚗️

Lyophobic Sols

"Solvent-fearing" • Irreversible
Pure Water
Add FeCl₃ or As₂O₃
Properties:
  • • Requires stabilizing agent
  • • Low viscosity
  • • Irreversible (cannot reform)
  • • Strong Tyndall effect

🔬 Perform Tests

Lab Notebook
Observations will appear here...