Question

Which of the following statements does not show the correct difference between adsorption and absorption? a.) In the adsorption , the substance is concentrated only at the surface while in absorption it is uniformly distributed in the bulk
b.) Adsorption is instantaneous while absorption is a slow process
c.) A substance can be adsorbed as well as absorbed simultaneously and the process is called sorption.
d.) Only gases are adsorbed while solids and liquids are absorbed

Answer 1

Hint: We know that adsorption and absorption are related with surface chemistry. These two are surface and bulk phenomena. In this question we will check option by option by basic concepts of absorption and adsorption.

Step by step solution:
Absorption is a phenomena in which assimilation of the molecular system throughout the bulk of the solid or liquid medium takes place. So, it is a bulk phenomenon. It is an endothermic process and temperature change has no effect. This process occurs at a uniform rate and concentration is constant throughout the medium.
Adsorption is a surface phenomenon in which accumulation of molecular species at the surface of liquid or solid takes place. It is an exothermic process and this process is influenced by low temperature. Rate of this process is not uniform, it increases steadily and reaches equilibrium. Concentration is not constant, it is different at the bottom of adsorbent from that in the bulk.
Sorption is a physical and chemical process by which one substance becomes attached to another. And sorption describes the actions of absorption and adsorption.

From the above explanation of adsorption and absorption we can conclude that:

“A” is the correct option, because adsorption is a surface phenomenon and absorption is a bulk phenomenon.

“B” is the correct option, because the absorption rate is uniform whereas in the adsorption rate increases steadily and reaches equilibrium.

“C” is the correct option, because in sorption both processes take place simultaneously.

“D” is the incorrect option, because there are different interfaces of adsorption and absorption like: gas-solid, liquid-solid, liquid-liquid, solid-solid and gas-solid.

Note: There is an opposite process of sorption which is called desorption. We have to remember all these specifications of these processes. So, don’t get confused between these simple mechanisms .