Diffusion and OsmosisOsmosis
Water and membranes
Osmosis is the diffusion of water across a partially permeable membrane — from a more dilute solution (higher water concentration) toward a more concentrated solution (lower water concentration).
Classroom example: A raisin in water swells as water enters. A raisin in very salty water may shrink.
Sort the examples
Water moving into a swollen raisin
Ink spreading in a glass of water
Potato strip in strong salt solution loses water
Smell of food cooking filling a kitchen
Osmosis
Diffusion (general)
Osmosis is a special case of diffusion — water + membrane.
Check your understanding
Why is a membrane important in the definition of osmosis, but not required for diffusion of perfume in air?