Question

Could you separate a colloid by filtering? Explain.

Answer 1

Hint: Colloid is a mixture consisting of dispersed phase and dispersed medium. The dispersed phase dissolves in the dispersed medium. Filtration is the process of separating one compound from another by using a filter paper. The size of colloidal particles is so small that they can pass through the normal filter paper.

Complete answer:
Solution is a homogeneous mixture of solute and solvent. The solute and solvent will be present as one phase in the solution.
When the dispersed phase is suspended in dispersed medium, it is referred to as colloid or colloidal solution. It is different from the true solution. As in the true solution there will be no continuous scattering of particles.
The size of colloidal particles ranges from $ 1nm $ to $ 1000nm $ , whereas the normal filter paper has a pore size of very greater than this range. Even a finest grade filter paper has a pore size of $ 2000nm $ . Thus, when the filter paper was used for the filtration of colloidal solution, the particles may go through the dispersed medium leading to the no use.
Thus, one cannot separate a colloid by filtering due to the small size of atoms and pore size of normal filter paper.

Note:
By the technique of ultra-filtration, the colloidal solution can be filtered. In ultra-filtration, the pores of the filter paper can be reduced by taking the filter paper and dissolving in gelatin and then hardening it by soaking in formaldehyde. By doing the above procedure, based on the size of colloidal particles, colloidal solutions can be separated.