Which one of the following statements is correct for adsorption of solutes on solids in solutions?
Which one of the following statements is correct for adsorption of solutes on solids in solutions?
The extent of adsorption increases with an increase in temperature
The extent of adsorption decreases with an increase of surface area of the adsorbate
The extent of adsorption decreases with an increase in temperature
The extent of adsorption does not depend on the amount of the solute in solution
Solution
(a) The extent of adsorption increases with an increase in temperature is an incorrect statement because an increase in temperature reduces the interaction between the absorbate molecules and adsorbent molecules.
(b) The extent of adsorption decreases with an increase of surface area of the adsorbate is also an incorrect statement as adsorption $\propto$ surface area of adsorbate.
(c) The extent of adsorption decreases with an increased in temperature.
$
\because \text { Adsorption } \propto \frac{1}{\text { temperature }}
$
Thus, is the correct statement.
(d) The extent of adsorption does not depend on amount of solute in solution.
This is also an incorrect statement because :
$
\frac{x}{m} \propto \operatorname{conc} .(C)^{1 / n}
$
where, $\frac{x}{m}=$ amount of adsorbent $(x)$, adsorbed on given mass $(m)$ of adsorbate and $n=$ an integer. Thus, plot of $\log \frac{x}{m} v s \log C$ gives a straight line upward slope.
Hence, option (c) is the correct answer