Question

Given below are three identical glasses (A, B, and C) containing mixtures having same appearance.

How can we identify which one is solution, suspension, and colloid?

Answer 1

Identifying the suspension:
Suspension is a heterogeneous mixture in which the particles are unstable and settle down if left undisturbed for some time.

The particles of glass C settle when they are left undisturbed. Thus glass C contains the suspension.
The particles in glass A and B do not settle when left undisturbed, so they must be a solution and a colloid.

Identifying the colloid and the solution:

Colloids: The size of particles of a colloid is too small to be individually seen by naked eyes but are big enough to scatter a beam of light passing through it and make its path visible.

Solution: The particles of a solution are smaller than 1 nm in diameter. So, they cannot be seen by naked eyes. Because of very small particle size, they do not scatter a beam of light passing through. So, the path of light is not visible in a solution.

Let's pass the beam of light using torchlight through the glasses A and B.

The particles present in the glass A scatters the beam of light passing through it and makes its path visible. Thus glass A contains the colloids.
The path of light is not visible in the glass B when the light is passed through it. Also, the particles are not visble to the naked eye. Thus, glass B contains the solution. [5 Mark]