Labs / Biology
Membrane Diffusion
A tank is split down the middle by a semipermeable membrane. Tiny water molecules slip through the pores, but the larger solute cannot — so water drifts toward the saltier side until both concentrations match. Move the sliders, or drag inside a chamber to sprinkle in more solute, and watch the levels shift.
CL —CR —flow —
What to try
- Make the left side much saltier than the right. Which way does the water go, and why does the level rise where the salt is?
- Can you find solute settings where the two levels stay perfectly even? What do the concentrations read then?
- What happens if one side starts as nearly pure water? How high can osmosis push the other side?
- Turn permeability down low. Does the tank still reach the same final levels — just slower, or somewhere different?
- Once it settles, sprinkle solute into the lower chamber. Can you reverse the direction of flow?