36.2.3 |
Langmuir Adsorption Isotherm
(contd..)
|
| |
Example 36.2: the volume of CH4 (corrected to STP) adsorbed per gram of charcoal at 240 K various pressures of CH4 is: |
| |
| P/(Torr) |
38 |
55 |
78 |
104 |
133 |
173 |
218 |
| V/(cm3.g-1) |
14.14 |
17.52 |
21.38 |
24.72 |
28.00 |
31.35 |
34.50 |
|
| |
Verify that the data obey Langmuir adsorption isotherm. Also determine Langmuir constant KL and the volume corresponding to complete surface coverage. Calculate the fraction of charcoal surface which is covered by
CH4 molecules at P = 150 torr.
Plot of p/V vs p as shown below is linear which shows that the data verify the Langmuir monolayer adsorption isotherm. |
| |
 |
Slope of the curve = 0.02 cm-3.g |
intercept = 2.05 torr cm-3 g =  |
| |
Fig 36.3 Langmuir adsorption isotherm for CH4 adsorbed on charcoal. |
| |
Fraction of the surface covered ( )
at P = 150 torr,
= 
= 0.593  59.3% of the surface is covered by CH4 molecules.
|
