C

Colloid

Quick Reference
Also Known AsColloidal dispersion, colloidal system, colloidal suspension, colloidal solution

What is Colloid?

A colloid (colloidal dispersion) is a mixture in which particles of one substance (1–1000 nm in size) are dispersed throughout another but not dissolved. Colloids differ from true solutions (smaller particles) and suspensions (larger particles that settle). Examples include milk (fat in water), fog (water droplets in air), and smoke (solid particles in air). Colloids scatter light (Tyndall effect).

Properties & Characteristics

A colloid (colloidal dispersion) is a heterogeneous mixture in which one substance (dispersed phase, 1–1000 nm particle size) is evenly distributed through another (dispersion medium). Colloids exhibit the Tyndall effect (light scattering), Brownian motion, and do not settle under gravity. Types include: sol (solid in liquid), aerosol (solid/liquid in gas), foam (gas in liquid), emulsion (liquid in liquid), and gel (liquid in solid).

Uses & Applications

Colloids are used in food science (milk, mayonnaise, ice cream), pharmaceuticals (drug delivery nanoparticles), cosmetics (creams, lotions), paints, inks, and industrial processes (wastewater coagulation). Gold colloids are used in lateral flow immunoassays and as catalysts.

Safety Information

Airborne colloidal particles (aerosols, nano-aerosols) are respiratory hazards; engineered nanoparticles may penetrate lung tissue. Colloidal solutions of toxic heavy metals (silver, gold, titanium nanoparticles) require nanomaterial safety protocols and environmental assessment.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Colloid
Synonyms Colloidal dispersion, colloidal system, colloidal suspension, colloidal solution

Frequently Asked Questions

A colloid (colloidal dispersion) is a mixture in which particles of one substance (1–1000 nm in size) are dispersed throughout another but not dissolved. Colloids differ from true solutions (smaller particles) and suspensions (larger particles that settle). Examples include milk (fat in water), fog (water droplets in air), and smoke (solid particles in air). Colloids scatter light (Tyndall effect).

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