What is adsorption?

Adsorption is when something sticks to another thing, just like when a sticker sticks to your notebook.

Imagine you have a sponge and some juice. When you press the sponge into the juice, it soaks up the liquid, that’s absorption. But adsorption is different: it's more like when a piece of tape sticks to your wall, not because it takes the wall inside it, but because it clings to the surface.

Think of a playground. You're a kid who loves to run around, and you see a swing that’s already occupied by another kid. You can’t just jump into the swing, you have to wait your turn. But if there's an empty spot on the swings, you attach yourself to it. That’s like adsorption, something (like you) sticks to a surface (the swing), not because it takes it over, but because it connects with it.

So when a gas or liquid sticks to the surface of a solid, that's adsorption, just like how your sticker attaches to your notebook.