Covers the classification of colloidal dispersed systems by the state of the dispersed phase and medium, with examples such as aerosols, lyosols and solid sols, and by lyophilic versus lyophobic behaviour. It then moves through Brownian motion, diffusion, sedimentation and optical effects such as the Tyndall effect, followed by macromolecular solutions, factors governing stability and coagulation, and colligative properties with their formulas. It closes with osmosis, the Hardy-Schulze law, the gold number and electro-osmosis.
Topic 7 of 42 in the MU Sofia syllabus for Chemistry (Dental Medicine, Year 1). The free AceMed note covers it in 11 sections, about 1,424 words (10 min of reading), with 22 flashcards.
In this note
Classification of Colloidal Disperse Systems:
Kinetic and optical properties of colloids.
Macromolecular Solutions
Stability and Coagulation of Colloidal Solutions:
Biological significance
Vapor pressure, boiling point elevation and freezing point depression
Diffusion, osmosis and law of osmotic pressure, Biological significance.
High-Yield Additions in Colloids & Colligative Properties
Hardy–Schulze Law
Gold Number
Electro-Osmosis
Classification of Colloidal Disperse Systems:
Based on the physical state of the dispersed medium:
Aerosols: Dispersed phase is a gas, dispersed medium can be liquid
Lyosols: Dispersed phase is a liquid, dispersed medium is another liquid
Solid sols: Dispersed phase is a solid, dispersed medium is a liquid
Examples:
Aerosols: Fog, mist, smoke, dust, hairspray.
Lyosols: Milk, blood, mayonnaise, emulsions (oil in water), sol of starch in water.
Solid sols: Paint, ink, mud, toothpaste, sols of metal nanoparticles in water.
Based on the interaction between the dispersed medium and the disperse phase:
Lyophilic: Dispersed particles have strong affinity for the dispersed medium, leading to good stability.
Lyophobic: Dispersed particles have weak affinity for the dispersed medium, leading to poor stability.
draw :
Examples:
Lyophilic: proteins
Lyophobic: oil in water emulsions
Additional notes:
The interaction between the dispersed phase and the dispersed medium is influenced by factors like surface charge, polarity, and the presence of stabilizing agents.
Lyophilic colloids are generally more stable than lyophobic colloids, but their stability can be affected by factors like temperature, electrolyte concentration, and pH.
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