Question

Explain absorption for physical absorption and chemical absorption?

Answer 1

Answer:

Absorption is a phenomenon involving the bulk properties of a solid, liquid or gas. It involves atoms or molecules crossing the surface and entering the volume of the material. As in adsorption, there can be physical and chemical absorption.

Physical absorption — A non-reactive process e.g. when oxygen present in air dissolves in water. The process depends on the liquid and the gas, and on physical properties like solubility, temperature and pressure.

Chemical absorption — A chemical reaction takes place when the atoms or molecules are absorbed. An example is when hydrogen sulphide is removed from biogas streams and converted into solid sulphur.

Answer 2

Answer:

In chemistry, absorption is a physical or chemical phenomenon or a process in which atoms, molecules or ions enter some bulk phase – liquid or solid material. This is a different process from adsorption, since molecules undergoing absorption are taken up by the volume, not by the surface (as in the case for adsorption). A more general term is sorption, which covers absorption, adsorption, and ion exchange. Absorption is a condition in which something takes in another substance.[1]

In many processes important in technology, the chemical absorption is used in place of the physical process, e.g., absorption of carbon dioxide by sodium hydroxide – such acid-base processes do not follow the Nernst partition law.

For some examples of this effect, see liquid-liquid extraction. It is possible to extract a solute from one liquid phase to another without a chemical reaction. Examples of such solutes are noble gases and osmium tetroxide.[1]

The process of absorption means that a substance captures and transforms energy. The absorbent distributes the material it captures throughout whole and adsorbent only distributes it through the surface.

The process of gas or liquid which penetrate into the body of adsorbent is commonly known as absorption.

IUPAC definition

Absorption: The process of one material (absorbate) being retained by another (absorbent); this may be the physical solution of a gas, liquid, or solid in a liquid, attachment of molecules of a gas, vapour, liquid, or dissolved substance to a solid surface by physical forces, etc. In spectrophotometry, absorption of light at characteristic wavelengths or bands of wavelengths is used to identify the chemical nature of molecules, atoms or ions and to measure the concentrations of these species.