QS Study

Difference between Lyophobic Colloid and Lyophilic Colloid

Lyophilic colloids are liquid loving colloids (Lyo means solvent and philic means loving). Example: Sols of organic substances like gelatin, gum, starch, and proteins. Lyophobic colloids are liquid hating colloids (Lyo means solvent and phobic means hating). Example: Sols of inorganic substances like Arsenic (As2S3), Iron (Fe(OH)3) and Platinum.

Lyophobic colloid: It forms a strong interaction between the dispersed phase and dispersion medium.

  • The only low concentration of the colloid is stable (usually 0.1-1%).
  • Dialysis is to be done by rigid control of electrolytes; complete removal of electrolytes breaks the colloid.
  • Relatively unstable.
  • Very sensitive to electrolyte concentration and coagulation is very easy.
  • After phase separation by coagulation, re-dispersion of the coagulum is difficult and needs special treatment.
  • The coagulation consists of discrete aggregated panicles.
  • Exhibits marked light scattering and strong Tyndall effect.
  • Most of the colloids are visible under high power microscope or ultramicroscope.
  • Surface tension very close or similar to that of the dispersion medium.
  • Viscosity is only slightly higher than that of the medium.
  • Exhibits no solution properties, such as the colligative properties. The colloid is a two-phase mixture.
  • Refractive index of the colloid does not follow any definite pattern.

Lyophilic colloid: It forms little or no interaction between dispersed phase and dispersion medium.

  • Relatively higher concentration can be attained without loss of stability.
  • Relatively stable to dialysis and often dialysis is not necessary.
  • Relatively stable.
  • Much less sensitive to electrolyte concentration; separation may occur at high electrolyte concentration.
  • Re-dispersion of the separated phase is quite easy.
  • Coagulation is often followed by ‘gel’ formation.
  • Light scatting is low and little or no Tyndall effect.
  • Most of the colloids are invisible even under ultramicroscope.
  • Surface tension is usually lower than that of the dispersion medium.
  • Viscosity is markedly increased.
  • Exhibits properties of the solution, such as colligative properties; only the molecules are of colloidal dimension.
  • Refractive index in most cases follows definite pattern like that of true solutions.