Question

Why are powdered substances more effective adsorbents than their crystalline forms?

Answer 1

Hint: The surface of the solid can attract and retain the molecules of the phase when substances come into contact. If These molecules remain only at the surface of the solid is adsorbent, the particles on adsorbent are adsorbate and the phenomenon is adsorption.

Complete step by step solution:
The accumulation of molecular species at the surface is termed as adsorption, which is a surface phenomenon. Especially solids like finely powdered states, which have large surface area exhibits adsorption.
For example, charcoal, colloids, clay, metals in the finely divided state are good adsorbents.
Examples of adsorption:
-Gases like ${{O}_{2}},C{{l}_{2}},{{H}_{2}},CO,N{{H}_{3}}$ are taken in a closed vessel containing charcoal powder. The gas molecule concentration increases at the surface of the charcoal when the pressure of the gas in the closed vessel decreases.
-The molecules of water adsorbed on the silica gel surface when the air becomes dry in presence of silica gel.
-if an aqueous solution of raw sugar, passed over animal charcoal, coloring substances adsorbed by charcoal.
Adsorption by the surface particles of the absorbent is not in the same environment in the solid. There are forces between inside the balanced particles. While on the surface the particles possess unbalanced residual attractive forces that are responsible for the adsorbate particles on its surface. The extent of adsorption increases with the increase in the surface area per unit mass of the adsorbent at a given temperature and pressure.
Finely powdered substances are more surface area than crystalline solids forms.

Hence, substances more effective adsorbents than their crystalline forms.

Note: If the molecules are uniformly distributed throughout the solid, this process is absorption, which process is completely different from adsorption process. For example, when a chalk stick is dipped in ink, the color of the surface will be blue. While inside the chalk sticks, it is white. This is an example of adsorption. Water vapors are absorbed by calcium chloride. This is a process of absorption.