The document discusses the classification of dispersed systems in physical pharmacy, identifying three types: molecular, colloidal, and coarse dispersions, distinguished by the size of the dispersed phase. It outlines their properties, including homogeneity, visibility, light scattering, settling behavior, permeability, and diffusion rates. Examples of each type are provided, such as urea for molecular dispersions and grains of sand for coarse dispersions.

1. Dispersion / Dispersed System
Physical Pharmacy 4th Semester
&
Types of Dispersed System
Molecular Dispersion
Colloidal Dispersion
Coarse Dispersion
ROHIT KUMAR TRIVEDI
UNIT-I
Lecture-1

2. Video Lecture Link
Click or Paste above given link to your internet browser
https://youtu.be/m8ic3QAT2As

3. There are three kind of Dispersed Systems:
1. Molecular 2. Colloidal 3. Coarse
Dispersion / Dispersed Systems
Dispersion (dispersed system) is a mixtures of two
substances, one of which (dispersed phase) is distributed
in form of subdivided particles/droplets/globules
throughout another substance (continuous phase,
dispersion medium).
▪ The only difference among them is the “size” of dispersed phase not its composition.
▪ Dispersions contain one internal phase that is dispersed in a dispersion medium.

4. Property Molecular Dispersions Colloidal Dispersions Coarse Dispersions
Homogeneity Homogeneous Heterogeneous Heterogeneous
Particle size Less than 1nm 1nm to 500nm (0.5μm) Greater than 500nm (0.5μm)
Visibility
Invisible under Electron
microscope
Visible under Electron microscope
May be detected under ultra-
microscope
Visible under microscope
Light Scattering No light scattering Show
Show
Appearance Clear Turbid Opaque
Settling Do not settle by gravity Particles settle by gravity Particles settle by gravity
Permeability
Pass through ultrafilter
paper & semipermeable
membrane
Pass through filter paper
Not through semipermeable
membrane
Do not pass through filter paper and
semipermeable membrane
Diffusion Rapid Slow No diffusion
Example Urea, sucrose and ions Silver sols, polymers, milk Grains of sand, red blood cells
Dispersion System: Classification

5. Rohit Kumar Trivedi
Assistant Professor, Pharmacy