In Langmuir's model of adsorption of a gas on a solid surface
- (A)the rate of dissociation of adsorbed molecules from the surface does not depend on the surface covered
- (B)the adsorption at a single site on the surface may involve multiple molecules at the same time
- (C)the mass of gas striking a given area of surface is proportional to the pressure of the gas✓ Correct
- (D)the mass of gas striking a given area of surface is independent of the pressure of the gas
Answer: (C)
Solution
Langmuir's treatment pictures a surface of equivalent single-molecule sites and balances the rates of adsorption and desorption. The rate at which gas molecules strike a given area, drawn from the kinetic theory of gases, is proportional to the number arriving per unit time, and that number is itself proportional to the gas pressure. The assumption built into the model is thus that the mass of gas striking a given area of surface is proportional to the pressure of the gas.
JEE Main · 2006 · 30 Apr 2006 · Offline · Single correct option