Question

Rate of physisorption increases with:
A) Decrease in temperature
B) Increase in temperature
C) Decrease in pressure
D) Decrease in surface area

Answer 1

Hint:‌The‌ ‌process‌ ‌of‌ ‌physiorption‌ ‌is‌ ‌an‌ ‌exthermic‌ ‌process.‌ ‌It‌ ‌is‌ ‌referred‌ ‌as‌ ‌physical‌ ‌adsoption.‌ ‌It‌ ‌depends‌ ‌on‌ ‌the‌ ‌area‌ ‌of‌ ‌the‌ ‌surface‌ ‌of‌ ‌the‌ ‌adsorbent‌ ‌present‌ ‌in‌ ‌the‌ ‌adsorption.‌ ‌The‌ ‌gas‌ ‌have‌ ‌the‌ ‌tendency‌ ‌in‌ ‌this‌ ‌adsorption‌ ‌to‌ ‌get‌ ‌accumulated‌ ‌on‌ ‌the‌ ‌solid‌ ‌surface.‌ ‌

Complete step by step answer:
The physisorption is a physical adsorption process which also depends on the surface area of the adsorbent. The rate of the process increases with the increase in the area of the adsorbent. The physisorption is more when the metal has been finely divided into particles or in the fine porous materials. As I said it is an exothermic process that means heat will be evolved during the process. We will use Le Chatelier principle for the determination of the effect of change in temperature or change in pressure on chemical equilibrium. The principle states that if some change has occurred in the system then the system has the tendency to change itself accordingly so the effect of the change that has been made or occurred should be negligible. So if the temperature gets increased then by the principle the system will be moving in the direction where the temperature will be decreasing. So the reaction will be moving backwards so the temperature will decrease. So from here we understood that the physisorption will increase with the decrease in the temperature.
so the correct answer is option ‘a’.

Note:The Le Chatelier principle is helpful in determining the equilibrium of the reactions. The reaction is in forward direction when the reactant concentration is increased. When the pressure is constant then the addition of inert gases will increase the volume so the product formation will be increased.