Question

(a) In reference to Freundlich adsorption isotherm, write the expression for adsorption of gases on solids in the form of an equation.
(b) Write an important characteristic of lyophilic solutions
(c) Based on the type of particles of the dispersed phase, give one example each of associated colloid and multimolecular colloid

Answer 1

The Freundlich equation or Freundlich adsorption isotherm, an adsorption isotherm, is an empirical relation between the concentration of a solute on the surface of an adsorbent to the concentration of the solute in the liquid with which it is in contact.

Complete step by step solution:
a) The Freundlich adsorption isotherm can be mathematically expressed as:
(for pressure)
$\dfrac{x}{m} =K{{p}^{\dfrac{1}{n}}}$
Taking log both sides, it would become: $\log \dfrac{x}{m} =\log K+\dfrac{1}{n} \log p$,
And (for concentration)
Where, x= mass of adsorbate
m= mass of adsorbent
p= Equilibrium pressure of adsorbate
c= Equilibrium concentration of adsorbate in solution,
Also, k and n are constant for a given adsorbate and adsorbent at a particular temperature.
At high pressure, $\dfrac{1}{n} =0$,
Hence, the extent of adsorption becomes independent of pressure.
b) Lyophilic sols are solvent attracting an important characteristic of these sols is that if the dispersion medium is separated the dispersion phase by any method, the sol can be reconstituted by simply remaining the two again. That is why these sols are also known as reversible sols.
c) Example of associated colloid: Soap solution
Example of multimolecular colloid: gold sol

Note: Colloids play an important role in the transfer of nutrients and pollutants in the environment over short and long distances. For example, colloids can transport nutrients such as phosphate through channels in the soil to deeper horizons, as well as over much longer distances in surface waters.