Dispersion System Flashcards
Dispersed Phase
Internal/Discontinuous Phase
Dispersion Medium
External/Continuous Phase
Classificiation of Dispersed Systems based on Particle Size
Molecular Dispersion
Colloidal Dispersion
Coarse Dispersion
Mixture of two or more components that form a homogenous molecular dispersion or one-phase system
Molecular Dispersion (True Solutions)
Represents a system having a particle size intermediate between that of a true solution & a coarse dispersion
Colloidal Dispersion
Diameter of particles being larger than 0.5 um
Coarse Dispersion
Molecular Dispersion
Size: <1nm
State: Monophasic
Visibility: Invisible in electron microscope
Filtration: Pass through ultrafilter and semipermeable membrane
Diffusion: Rapid
Examples of Molecular Dispersion
Glucose
Oxygen Molecules
Ordinary Ions
Colloidal Dispersion
Size: 1nm - 0.5um
State: Biphasic
Visibility: Visible in electron Microscope
Filtration: Pass through filter paper but not semipermeable membrane
Diffusion: Slow
Examples of Colloidal Dispersion
Colloidal Silver Solution
Paint
Shaving Cream
Natural & Synthetic Polymers
Milk, Cheese, Butter
Coarse Dispersion
Size: >0.5um
State: Biphasic
Visibility: Visible under microscope
Filtration: Do not pass through filter paper or semipermeable membrane
Diffusion: No diffusion
Examples of Coarse Dispersion
Most pharmaceutical emulsion and Suspension
Grains of Sand
Red Blood Cells
Types of Colloidal System
(a) Lyophilic Colloids
(b) Lyophobic Colloids
(c) Association Colloids
Lyophilic Colloids
Solvent loving colloids
Thermodynamically Stable
Dispersion Medium: Water
Examples of Lyophilic Colloids
Dispersion of starch, gum, protein in water
Lyophobic Colloids
Solvent-hating Colloids
Thermodynamically Stable
Dispersion Medium: Water - Hydrophobic colloids
Consist of inorganic particles
Examples of Lyophobic Colloids
Dispersion of Gold, Sulfur, Silver iodide in water
Composed of material that have little attraction for the dispersion medium, due primarily to the absence of a solvent sheath around the particles
Lyophobic Colloids
Association Colloids / Amphiphilic Colloids
Having two distinct regions of opposing solution affinities
Formed by association of dissolved molecules of a substance to create particles of colloidal dimensions
Association / Amphiphilic Colloids
Systems containing colloidal particles that interact to an appreciable extent with the dispersion medium
Lyophilic Colloids
The concentration of monomer at which micelles form
Critical Micelle Concentration
The number of monomers that aggregate to form a micelle
Aggregation Number
Dispersion Medium: Solid
Solid: Solid Solution
Liquid: Solid Emulsion
Gas: Solid Foam
Dispersion Medium: Liquid
Solid: Sol, Gel
Liquid: Emulsion
Gas: Foam
Dispersion Medium: Gas
Solid: Solid aerosols
Liquid: Liquid Aerosols
Colloid Type of Pearls, Opal
Solid solution
Colloid Type of Cheese, butter
Solid emulsion
Colloid Type of Pumcie, Marshmallow
Solid Foam
Colloid Type of Jelly, Paint
Sol, Gel
Colloid Type of Milk, Mayo
Emulsion
Colloid Type of Whipped cream, shaving cream
Foam
Colloid Type of Smoke, Dust
Solid aerosols
Colloid Type of Cloud, mist, fog
Liquid aerosols
Properties of Colloids
1. Optical
* Light Scattering
2. Kinetic
* Brownian Motion
* Diffusion
* Sedimentation
* Viscosity
3. Electrical
* Zeta Potential
* Nerns’t Potential
* Electrokinetic Potential
Optical properties
Faraday-Tyndall Effect
Random movement of colloidal particles, irregular & zigzag pattern
Brownian Motion
Factors affecting Brownian Motion
↑ Particle Size ↓ Velocity
↑ Viscosity ↓ Brownian Movement
Size of particles
MW
Affinity of particle
Spherocolloids - ↓ Viscosity
Linear particles - ↑ Viscosity
Spontaneous movement of particles from a region of higher concentration to one of lower concentration until equilibrium is achieved.
Diffusion
Ruled by Fick’s law
Resistance to flow a system under applied stress
Viscosity
Zeta Potential is also known as
Electrokinetic Potential
Difference in potential between the surface of the tightly-bound layers & the electroneutral region of the dispersion
Zeta Potential/Electrokinetic Potential
Nerns’t Potential
Electrokinetic Potential
Difference in potential between the actual surface of the particle & the electroneutral region of the dispersion
Nerns’t Potential/Electrothermodynamic Potential
Electrokinetic phenomena
Electrophoresis
Electro-osmosis
Sedimentation Potential
Streaming Potential
The presence and magnitude, or absence of this on colloidal particle is an important factor in determining stability of colloids
Electric Properties
The movement of a charged particles through a liquid under the influence of an applied potential difference
Electrophoresis/Cataphoresis
The movement of the dispersion medium under the influence of applied potential
Electro-osmosis
Creation of potential when particles undergo sedimentation
Opposite of electrophoresis
Sedimentation Potential
Creation of potential by a forcing a liquid to flow through a plug or bed of particles
Streaming potential
Pharmaceutical use of Colloidal Copper
Treatment of Cancer
Pharmaceutical use of Colloidal Mercury
Treatment of Syphilis
Pharmaceutical use of Colloidal Gold
Diagnostic Agent for paresis
Pharmaceutical use of Colloidal Electrolytes
Inc. solubility, stability, and taste of compounds in aq and oil pharmaceutical prep
Pharmaceutical use of Colloidal Sulfur
Absorbed completely compare to powdered sulfur