Which of the following expressions describes Freundlich adsorption isotherm?

Options

A. `log"(x)/(m)=log k +(1)/(n)log P`
B. `log"(x)/(m)=log k -(1)/(n)log P`
C. `log"(x)/(m)=log k + n log P`
D. `log"(x)/(m)=log k - n log P`

Answer

D

Explanation

The empirical relationship called Freundlich adsorption isotherm is usually given as
`(x)/(m)=kP^(1//n)`
Taking logarithm of both sides we get
log `(x)/(m)=logk+(1)/(n)logP`
The validity of Freundlich isotherm can be verified by plotting log `x//m` on y-axis (ordinate) and log `P` on x-axis (abscissa). If it comes to be a straight line, the Freundlich isotherm is valid.

The slope of the straight line gives tha value of `1//n` while the intercept on the y-axis gives the value of log `k` .
The factor `(1)/(n)` can have value between `0` and `1` but log equation holds good over a limited range of pressure with probable range of factor `(1)/(n)` form `0.1` to `0.5`. Thus, Freundlich adsorption isotherm example the behaviour of adsorption curve in an approximate manner.