Surface Chemistry

In Langmuir’s mode of adsorption of a gas on a solid surface

  1. the adsorption at a single site on the surface may involve multiple molecules at the same time.
  2. the mass of gas striking a given area of surface is independent of the pressure of the gas.
  3. the mass of gas striking a given area of surface is proportional to the pressure of the gas.
  4. the rate of dissociation of adsorbed molecules from the surface does not depend on the surface covered.

Answer

Assuming the formation of a monolayer of the adsorbate on the surface of the adsorbent, it was derived by Langmuir that the mass of the gas adsorbed per gram of the adsorbent is related to the equilibrium pressure according to the equation:

 x/m = ap/(1+bp)

 where x is the mass of the gas adsorbed on m gram of the adsorbent, P is the pressure and a, b are constants.

The correct option is C.