Solution, Suspension and Colloid.
After sometime.
Let us understand this with the help of an activity.
Take some water in 3 separate beakers.
Sugar.
Lemonade.
Add sugar in the 1st beaker.
Lemon?
Add chalk powder in the 2nd beaker.
Add milk in the 3rd beaker.
Stir all the mixtures.
Direct a beam of light through each beaker.
The particles of sugar have completely disappeared in the mixture.
Such a mixture is called a homogeneous mixture.
Homogeneous means consistent or uniform throughout.
The particles of sugar are very small.
They cannot scatter any light.
Hence, we are unable to see the path of light inside the Homogeneous mixture.
Such a mixture is called a solution.
The size of particles in a solution is usually less than 1 nm.
We can observe some chalk particles freely moving in the 2nd mixture.
Such a mixture is called a heterogeneous mixture.
Heterogeneous means non-uniform.
Light is directed through the 2nd beaker.
Here, the path of light is visible inside the heterogeneous mixture.
The particles of chalk are insoluble in water and are big enough to scatter the light passing through them.
Such a mixture is called a suspension.
This effect of scattering of light is called Tyndall effect.
Size of particles in a suspension is usually larger than 1000 nm.
However, these particles eventually settle down.
After some time, the Tyndall effect may not be observed in suspensions.
Let us have a look at the 3rd mixture.
Path of light is visible through the mixture.
Mixture appears to be Homogeneous, but when observed under a highly powered microscope, it is actually a heterogeneous mixture.
Such a mixture is called a colloid.
Size of particles is between 1 nm and 1000 nm.
In a colloid, the particles never settle down.
Hence, the Tyndall effect is always observed in colloids.