I need to use the following data and equation to get the K value and plot the Langmuir isotherm, θ vs P, for a system where nitrogen adsorbes/desorbes molecularly from a surface.
Data:
ΔHads= 30 KJ/mol, T = 300 K, τ0 = 1x10-12 s, cross sectional area of N2 = 16.2 A2 .
I must use the following equation to solve for K:
K = [[NA*σ0*τ0] / [2π(MRT)]^1/2] exp(Q/RT)
Q = activation Energy (which means it is = ΔHads= 30 KJ/mol)
After solving for K (where I have difficulty because I get a HUGE number) I must use the following equation (2) where we input the desired number of pressures in Pascals from (0.1 to 1.0) which will give me the different coverage for such pressure.
θ= (P*K1) / 1 + (P*K)
After getting the K values, we insert the desired P (pressure) from 0.1 to 1.0 to get the Langmuir isotherm graph (theta vs P).
Can someone help me with this? I don't get the right answer whenever I do the question. Maybe one of my equations is wrong? Please let me know.
Sachin Liyanage, You did not specify the unit of constant K in given formula. Heats of physisorption are of the order of several kJ/mol and there may be mistake here. The heat of adsorption is not the activation energy of adsorption.
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