## Adsorption from Solution Phase Chemistry Notes

→ The solids can also adsorb solutes from solutions also. When the coloured solution is shaken with charcoal then coloured dye is adsorbed by the charcoal and the solution becomes colourless. The following observations have been made in the case of adsorption from solution phase:

• The extent of adsorption decreases on increasing temperature because the kinetic energy of solute increases.
• The extent of adsorption increases on increasing surface area of adsorbent.
• The extent of adsorption depends on the concentration of solution. → The extent of adsorption can be represented by the following equation :
$$\frac{x}{m}$$ = kc1/2
Taking logarithm of above equation on both side
log $$\frac{x}{m}$$ = log k + $$\frac{1}{n}$$ log c
where, c = Concentration of solute at equilibrium
x = Amount of adsorbed solute
m = Mass of solid adsorbent
n = Constant
k = Constant On plotting the curve between log$$\frac{x}{m}$$ and log c, it is found to be similar to one shown in fig. 5.6
In this curve, slope gives the value of $$\frac{1}{n}$$ while intercept
will give the value of log k.
Value of constant k depends upon the nature of solid, size of particle, temperature, nature of solute and solvent.