Study Set Content:
The concentration of monomer at which
micelles form is termed the
critical micelle concentration (CMC).
The number of monomers that aggregates to form a micelle is
known as the
aggregation number of the micelle.
Sodium lauryl sulfate
Anionic
Benzalkonium chloride
Cationic
Tweens and Spans
Nonionic
Dimethyl Idodecylammoniopropane sulfonate
Ampholytic
PROPERTIES OF COLLOIDS
A. Optical
B. Kinetic
1. Thermal
2. Gravitational
3. Applied External
When a strong beam of light is passed through a colloidal
solution a visible cone (ultramicroscope), resulting from the
scattering of light by the colloidal particles is formed.
Faraday-Tyndall Effect
In case of lyophilic solution, the colloidal particles are highly
solvated, which results into lower difference in refractive
index of two phases. In lyophilic solution, Tyndall effect is
not pronounced
, the difference is quite large
and it shows Tyndall effect.
lyophobic solution
• This property depends on the Faraday-Tyndall effect and is
widely used for determining the molecular weight of colloids.
Light scattering
It can be used to obtain information on the shape and size of
these particles.
Light scattering
Scattering can be described in terms of the
turbidity, t,
the
fractional decrease in intensity due to scattering as the incident
light passes through 1 cm of solution.
turbidity, t,
The turbidity is proportional to the
M.W. of the lyophilic colloid.
Describes the random movement of colloidal particles.
Brownian Motion
The erratic motion, which may be observed with particles
as large as about 5 μm, resulted from the bombardment of
the particles by the molecules of the dispersion medium.
Brownian Motion
The velocity of the particles increases with decreasing particle
size
Increasing the viscosity of the medium, which may be
accomplished by the addition of glycerin or a similar agent,
decreases and finally stops the Brownian movement.
Is a direct results of Brownian movement.
Diffusion
