The correct statement(s) pertaining to the adsorption of a gas on a solid surface is(are):a)Adsorption is always exothermic b)Physisorption may transform into chemisorption at high temperaturec)Physisorption increases with increasing temperature but chemisorption decreases with increasing temperature.d)Chemisorption is more exothermic than physisorption, however, it is very slow due to high energy of activation.Correct answer is option 'A,B,D'. Can you explain this answer?

Question

Answer

A option wrong case of H2 is endothermic

Answer

Adsorption of a Gas on a Solid Surface

Adsorption is always exothermic

Adsorption is the process of accumulation of molecules or atoms of a substance on the surface of another substance. When a gas is adsorbed on a solid surface, it involves the attractive forces between the gas molecules and the solid surface. These attractive forces result in the release of energy in the form of heat, making the process exothermic. Therefore, option A is correct.

Physisorption may transform into chemisorption at high temperature

Physisorption, also known as physical adsorption, occurs due to weak van der Waals forces between the gas molecules and the solid surface. These forces are temporary and reversible. On the other hand, chemisorption involves the formation of chemical bonds between the gas molecules and the solid surface. At high temperatures, the energy available for the system increases, leading to the breaking of weak van der Waals forces and the formation of stronger chemical bonds. Therefore, physisorption may transform into chemisorption at high temperatures. This means that option B is correct.

Physisorption increases with increasing temperature but chemisorption decreases with increasing temperature

Physisorption is favored by low temperatures because at low temperatures, the molecules have lower kinetic energy, allowing them to come closer to the solid surface and be adsorbed. As the temperature increases, the kinetic energy of the gas molecules also increases, making them move faster and reducing their chances of being adsorbed. Therefore, physisorption decreases with increasing temperature.

On the other hand, chemisorption involves the formation of chemical bonds, which require a certain amount of activation energy to occur. Increasing the temperature provides more energy for the reaction, making it easier for the chemical bonds to form. Therefore, chemisorption increases with increasing temperature. Therefore, option C is not correct.

Chemisorption is more exothermic than physisorption, however, it is very slow due to high energy of activation

Chemisorption involves the formation of chemical bonds, which are stronger than the weak van der Waals forces involved in physisorption. Therefore, chemisorption is more exothermic than physisorption.

However, chemisorption is a slower process compared to physisorption due to the high energy of activation required for the formation of chemical bonds. The energy of activation is the minimum energy required for a chemical reaction to occur. It acts as a barrier to the reaction, making chemisorption a slower process. Therefore, option D is correct.

To summarize, the correct statements pertaining to the adsorption of a gas on a solid surface are:
a) Adsorption is always exothermic.
b) Physisorption may transform into chemisorption at high temperature.
d) Chemisorption is more exothermic than physisorption, however, it is very slow due to high energy of activation.

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