Comprehension Passage
Adsorption is a critical surface phenomenon where molecules of a substance, referred to as the adsorbate, accumulate on the surface of another substance called the adsorbent, rather than being distributed throughout the bulk. This process is pivotal in various industrial applications due to its specificity and efficiency in separating substances based on their physical and chemical properties. Physisorption involves weak van der Waals forces and is generally reversible, making it suitable for applications where temporary surface interactions are required. In contrast, chemisorption involves strong chemical bonds, typically covalent or ionic, leading to irreversible changes. This type is essential for processes requiring stable and permanent adsorption, such as catalysis in chemical reactors.
Considering the thermodynamics of adsorption, which statement accurately reflects the entropic changes associated with physisorption?
1
Entropy increases due to the disorder introduced by adsorbate at the surface.
2
Entropy decreases as the adsorbate molecules become more ordered on the adsorbent surface.
3
Entropy remains unchanged as the kinetic energy of the adsorbate compensates for its positional order.
4
Entropy initially decreases, then increases as the adsorbate layers build up.