Water Potential & the Direction of Osmosis

Two solutions share a membrane. Set each side's solute potential Ψ_s and pressure potential Ψ_p; the sim computes Ψ = Ψ_s + Ψ_p and shows which way water flows. Water always moves toward lower (more negative) Ψ.

Try: make both sides equal, then add pressure (Ψ_p) to the side with more solute. A wall pushing back (turgor) can RAISE Ψ until the two sides match — that is how a plant cell reaches equilibrium without the solute concentrations being equal.