Q.Answer in one sentence:
Write an equation for Freundlich adsorption isotherm.

An adsorption isotherm is the relationship, at constant temperature, between the amount of a substance adsorbed per unit mass of adsorbent and the equilibrium pressure (for a gas) or concentration (for a solution). The Freundlich adsorption isotherm is an empirical equation for this relationship: $\frac{x}{m} = k P^{1/n}$ (with $n>1$), where $x$ is the mass of gas adsorbed, $m$ is the mass of adsorbent, $P$ is the equilibrium pressure, and $k$, $n$ are constants depending on the adsorbate, adsorbent and temperature (for solutions, $P$ is replaced by concentration $C$). Taking logarithms gives $\log\frac{x}{m} = \log k + \frac{1}{n}\log P$, a straight line whose slope is $\frac{1}{n}$ (always between 0 and 1) and whose y-intercept is $\log k$. When $\frac{1}{n} \to 0$, adsor …