Question

Show graphically how the amount of a gas adsorbed on a solid in physical adsorption varies with temperature.

How does adsorption of a gas on a solid surface vary with temperature? Illustrate with the help of appropriate graph.

Answer 1

The graph shows an adsorption isobar, i.e., a plot of `x/m`​ (mass of gas adsorbed per unit mass of adsorbent) against temperature (t) at constant pressure.

In physical adsorption, the extent of adsorption decreases continuously with an increase in temperature. This is because the process is exothermic, and higher temperature discourages adsorption by supplying energy for desorption.

Hence, the curve slopes downward, as shown in the graph.