Question

Discuss the effect of pressure and temperature on the adsorption of gases on solids.

Answer 1

As we increase the pressure of the system, the particles of gases will have a greater chance to interact with the surface of the solid. As we increase the temperature, the bonds through which the gas and solid are connected may get weaker.

Complete step by step solution:
Adsorption of gas on solid is the process in which molecules of gas get adsorbed on the surface of solid. Thus, it is a surface phenomenon. The gas molecule may form various kinds of bonds in order to get adsorbed.
Now, we will see the effects of physical parameters such as temperature and pressure on the adsorption of gases on solid surfaces.
Pressure:
As we increase the pressure of the system, the particles of gases will come closer and as a result they will have a greater chance to get adsorbed on the surface of the solid because of increased pressure. So, by increasing the pressure of the system, the adsorption of gas on a solid surface will increase. As we decrease the pressure of the system, the particles of the gases will have more volume and as a result they will comparatively get less bound to the solid surface. Thus, adsorption will decrease. So, we can conclude that on increasing pressure, the adsorption of gases on solid surfaces will increase and vice-versa.
Temperature:
We know that as we increase the temperature, the energy of the gas increases. At the same time, the gas which is bonded with solid surface will also break the bond with the surface of solid and we find that as a result the adsorption decreases as we increase the system temperature. As we decrease the temperature, this breakage of bonds decreases and we can say that adsorption will increase as we decrease the temperature and vice-versa.

Thus, we can conclude that on increasing pressure, the adsorption of gas on solid increases and on increasing temperature, the adsorption of gas decreases and vice-versa.

Note: Remember that absorption is a different phenomenon than adsorption. Absorption involves the whole material of the absorbate while adsorption is just a surface phenomenon. There is no real effect of changes in pressure and temperature on absorption.