Question

Which of the following will not represent an adsorption process?

• A. Powdered charcoal in methylene blue solution
• B. Gases like $O_2,H_2,CO,C{l}_2,N{H}_{3}orS{O}_2$ is taken in a closed vessel containing charcoal.
• C. Aqueous solution of raw sugar passed over beds of animal charcoal.
• D. Anhydrous $CaC{l}_2$ in a desiccator

Answer 1

The correct option is D Anhydrous $CaC{l}_2$ in a desiccator

Adsorption is the accumulation of molecular species at the surface rather than in the bulk of a solid or liquid.

Solid surface has tendency to attract and retain other phase particles. Such particles remain at surface without moving deep into the bulk.

In (a), methylene blue will get adsorbed to the surface of charcoal.

In (b), $O_2,H_2,CO,C{l}_2,N{H}_{3}andS{O}_2$ will get adsorbed to the surface of charcoal.

In (c), the colouring substances in raw sugars gets adsorbed by the charcoal and result in a white sugar.

In absorption, substance is uniformly distributed throughout the bulk of the solid.
In (d), anhydrous $CaC{l}_2$ will absorb water vapours/molecule in the surrounding. Water will not stop at the surface, it will move inside the bulk.

Hence, it is not a adsorption process.