--%>
Assignment Help - homework help

What is adsorption and its examples.

In a liquid a solid substance a molecule present within the bulk of the substance is being attracted infirmly from all sides by the neighbouring molecules. Hence there is no bet force acting on the molecule or there are no unbalanced forces of the molecule. On the other hand, a molecule present at the surface is not attracted to other molecules form all sides because there are no neighbouring molecules above the surface. Hence, it possesses some unbalanced or residual forces. As a result of these unbalanced forces the molecules present at the liquid surfaces tend to satisfy their residual forces by attracting the molecules of other species when brought in contact with them and retaining them on the surface. This causes increase in concentration of the molecular species near the surfaces as compared to its bulk phases. This accumulation of molecular species at the surface rather than in bulk of a solid or liquid is referred to as adsorption. The molecular species or a substance which concentrates or accumulates at the surface is called adsorbate. The material on the surface of which adsorption is called adsorbent.

The adsorbate and adsorbent process of removal of an adsorbed substances from surfaces is called desorption. It is reverse of adsorption and can be brought about by reducing the pressure or by heating.

Some examples of adsorption

(i) When gases like O2, H2, CO, Cl2, NH3 or SO2, are taken in a closed vessel containing powdered charcoal. It is observed that the pressure of the enclosed vessel decreases. The gas molecules get adsorbed on the surface of charcoal.

(ii) Aqueous solution of raw sugar when passed over beds of animal charcoal becomes colourless because the colouring matter of sugar is adsorbed by the animal charcoal surface.

(iii) The air becomes dry in the presence of silica gel because water molecules get adsorbed on the surface of silica gel.

(iv) When animal charcoal is added to a solution of some organic dye (say methylene blue) and the contents are filtered after thorough shaking, it is observed that the filtrate is almost colourless. The molecules of the dye are adsorbed on the surface of animal charcoal.

The above examples clarify that the solid surfaces can hold the gas or liquid molecules because of adsorption.

   Related Questions in Chemistry

  • Q : Problem on solutions The 2N aqueous

    The 2N aqueous solution of H2S04 contains: (a) 49 gm of H2S04 per litre of solution (b) 4.9 gm of H2S04 per litre of solution (c) 98 gm of H2S04

    		•
  • Q : What is ortho effect? Orthosubstituted

    Orthosubstituted anilines are generally weaker bases than aniline irrespective of the electron releasing or electron withdrawing nature of the substituent. This is known as ortho effect and may probably be due to combined electronic and steric factors.The overall basic strength of ort

    		•
  • Q : Soluation of Ideal Gas Law problems

    Explain the method, how do you solve Ideal Gas Law problems?

    		•
  • Q : HCl is polar or non-polar Can you

    Can you please illustrate that HCl is polar or non-polar? Briefly illustrate it.

    		•
  • Q : Relative reactivity Which is more

    Which is more reactive towards nucleophilic substitution aryl halide or vinyl halides

    		•
  • Q : Explain gels and its various categories.

    Certain sols have the property of setting to a semi-solid, jelly-like form by enclosing the entire amount of liquid within itself when they are present at high concentrations. This process is called gelation and colloidal systems with jelly-like appearance are known as gels. Some common examples

    		•
  • Q : Why aryl halides are less reactive?

    Aryl halides are much less reactive towards nucleophilic substitution reactions than haloalkanes. The less reactivity of aryl halides can be described

    		•
  • Q : Reducible Representations The number of

    The number of times each irreducible representation occurs in a reducible representation can be calculated.Consider the C2v point group as described or Appendix C. you can see that (1) sum of

    		•
  • Q : Chem Silicon has three naturally

    Silicon has three naturally occurring isotopes. 28Si, mass = 27.976927; 29Si, mass = 28.976495; 30Si, mass = 29.973770 and 3.10% abundance. What is the abundance of 28Si?

    		•
  • Q : Procedure to judge that organic

    Describe briefly the procedure to judge that the given organic compound is pure or not?

    		•