Question

(a) In reference of 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 type of particles of dispersed phase, give one example each of associated colloid and multimolecular colloid.

Answer 1

(a) The freundich adscription isotherm is mathematically expressed as

$\frac{x}{m}=K{p}^{1/n}$

It is also written as

$log\frac{x}{m}=logK+\frac{1}{n}logp$

or,

$\frac{x}{m}=K{c}^{1/n}$

It is also written as

$log\frac{x}{m}=logK+\frac{1}{n}logc$

where,

x = mass of adsorbate

m = mass of adsorbent

p = Equlibrium pressure of adsorbate

c = Equilibrium concentration of adsorbate in solution

K and n are constant for a given adsorbate and adsorbent at a particular temperature.

At high pressure, 1/n = 0, hence, extent of adsorption becomes independent of pressure

(b) Lyophilic sols are that 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