Lecture Notes on Colloids

Definition of Colloids

• Colloids are dispersed substances, not dissolved.
• Comprise small groupings or large molecules (e.g., hemoglobin) that scatter light.

Examples of Colloids

• Fog: Liquid dispersed in air (solvent), formed by tiny water droplets.
• Smoke: Particulates from combustion (e.g., carbon) dispersed in air.
• Whipped Cream: Foam type colloid; gas dispersed into liquid.
• Soap: Sodium stearate, produced via sodium/potassium hydroxide action on fat.

Structure of Soap

• Composed of 18 carbon atoms and a carboxylate functional group.
• Carboxylate group is polar; the carbon chain is nonpolar.
• Soap molecules form micelles in water, hiding nonpolar parts (hydrophobic).

Micelle Formation

• Soap molecules in water form micelles with polar heads outward, nonpolar tails inward.
• The structure scatters light, creating colloidal dispersion.

Micelle Functionality

• Soaps remove grease by micelles encapsulating oil droplets, forming oil in water dispersion.

Applications of Micelles

• Potential use in drug delivery by encapsulating non-polar drugs in micelles.

Conclusion

• Colloids are versatile with diverse applications in everyday and scientific fields.
• Provides a unique mechanism for cleaning and potential medical applications.

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