A colloid is a mixture with particles between 1-1000 nanometers that remain evenly dispersed throughout the solution rather than settling. Colloids exhibit several unique optical and kinetic properties including the Tyndall effect where light is scattered by colloidal particles, Brownian motion where particles move randomly due to impacts from dispersion medium molecules, and diffusion where particles move from areas of higher to lower concentration over time.

1. A colloid is one of the three primary types of mixtures,
with the other two being a solution and suspension. A
colloid is a solution that has particles ranging between
1 and 1000 nanometers in diameter, yet are still able
to remain evenly distributed throughout the solution.
These are also known as colloidal dispersions because
the substances remain dispersed and do not settle to
the bottom of the container
INTRODUCTION-

2. TYPES of colloids-

3. OPTICAL PROPERTIES
OF COLLIDES
The optical properties
of a material define how
it interacts with light

4. Tyndall effect-
Tyndall in 1869, observed that if a strong beam of light is passed
through a colloidal solution then the path of light is illuminated. This
phenomenon is called Tyndall Effect. This phenomenon is due to
scattering of light by colloidal particles.

5. KINETIC PROPERTIES
OF COLLIDE
1. Brownian movement
2. Diffusion
3. Sedimentation
4. Osmotic pressure
5. Viscosity

6. Brownian Movement-
It is also termed as Brownian motion and is named after its
discoverer Robert Brown (a Botanist.) Brownian motion is
the zig-zag movement of colloidal particles in continuous
random manner. Brownian motion arises because of the
impact of the molecules of the dispersion medium on the
particles of dispersed phase. The forces are unequal in
different directions. Hence it causes the particles to move
in a zig-zag way.

7. Diffusion-
Due to Brownian Motion particles move from regionof
higher concentration to region of lower
concentration.According to the Fick's first law:
Dm/dt = -DA dc/dx
D = Diffusing constant
dm = mass of substance diffusing in time dt across anarea
A under influence of concentration gradient dc/dx
The minus sign denotes that diffusion takes place in thedirection of
decreasing concentration.The measured diffusion coeffecient can
be used todetermine the radius of particles or molecular weight.

8. Sedimentation-
At small particle size (less than 0.5 um) Brownian motion is
significant & tend to prevent sedimentation due to gravity &
promote mixing instead. So, we use an ultracentrifuge which
provide stronger force so promote sedimentation in a
measurablemanner.