Why is adsorption always exothermic?
(N/A) Adsorption is always exothermic. This can be explained in two ways:
$(i)$ Adsorption leads to a decrease in the residual forces on the surface of the adsorbent. This causes a decrease in the surface energy of the adsorbent,which is released as heat. Therefore,adsorption is always exothermic.
$(ii)$ From the thermodynamic perspective,for a process to be spontaneous,the Gibbs free energy change,$\Delta G$,must be negative. The relationship is given by $\Delta G = \Delta H - T\Delta S$. When a gas is adsorbed on a solid surface,its movement is restricted,leading to a decrease in entropy,i.e.,$\Delta S$ is negative. Since $\Delta G$ must be negative and $\Delta S$ is negative,$\Delta H$ must be negative to satisfy the equation. Hence,adsorption is always exothermic.
$(i)$ Adsorption leads to a decrease in the residual forces on the surface of the adsorbent. This causes a decrease in the surface energy of the adsorbent,which is released as heat. Therefore,adsorption is always exothermic.
$(ii)$ From the thermodynamic perspective,for a process to be spontaneous,the Gibbs free energy change,$\Delta G$,must be negative. The relationship is given by $\Delta G = \Delta H - T\Delta S$. When a gas is adsorbed on a solid surface,its movement is restricted,leading to a decrease in entropy,i.e.,$\Delta S$ is negative. Since $\Delta G$ must be negative and $\Delta S$ is negative,$\Delta H$ must be negative to satisfy the equation. Hence,adsorption is always exothermic.
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Similar Questions
Given below are the critical temperatures of some of the gases:
Gas Critical temperature $(K)$ $He$ $5.2$ $CH_{4}$ $190$ $CO_{2}$ $304.2$ $NH_{3}$ $405.5$
The gas showing least adsorption on a definite amount of charcoal is:
| Gas | Critical temperature $(K)$ |
| $He$ | $5.2$ |
| $CH_{4}$ | $190$ |
| $CO_{2}$ | $304.2$ |
| $NH_{3}$ | $405.5$ |
The gas showing least adsorption on a definite amount of charcoal is:
Which of the following statements is incorrect?
Easy
View SolutionAssertion $(A)$: The property of adsorption is shown to a greater extent by solids than liquids.
Reason $(R)$: Solids like charcoal and silica can act as good adsorbents.
Reason $(R)$: Solids like charcoal and silica can act as good adsorbents.
Which of the following is $NOT$ a characteristic of chemisorption?
Given below are two statements. One is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A :$ Activated charcoal adsorbs $SO_{2}$ more efficiently than $CH_{4}$.
Reason $R$ : Gases with lower critical temperatures are readily adsorbed by activated charcoal.
In the light of the above statements,choose the correct answer from the options given below.
Assertion $A :$ Activated charcoal adsorbs $SO_{2}$ more efficiently than $CH_{4}$.
Reason $R$ : Gases with lower critical temperatures are readily adsorbed by activated charcoal.
In the light of the above statements,choose the correct answer from the options given below.
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