Osmosis and Diffusion Lab Kit

The Osmosis and Diffusion Lab Kit gives students a hands-on investigation of passive transport, the movement of substances across a cell membrane without energy input. Working in groups, students compare diffusion and osmosis directly, observing how each process moves material across a semi-permeable barrier and identifying what the two have in common and where they differ.

In the diffusion portion, dialysis tubing stands in for a semi-permeable membrane, and a starch-iodine colorimetric test makes solute movement visible: as iodine crosses the membrane and contacts starch, a color change marks where the solute has traveled, letting students see diffusion rather than simply infer it. In the osmosis portion, students set up conditions that should drive water movement across the membrane, then collect data over time to determine whether osmosis occurred and in which direction. Together the two parts turn abstract textbook definitions into measurable, observable results.

The kit contains enough materials for 15 student groups and includes a teacher's manual along with student study guide copymasters, so an instructor can run the lab across multiple class sections without additional preparation. Supplied components include starch, sucrose, iodine and potassium iodide solution, dialysis tubing, and plastic cups. To complete the procedure, a lab will also need items not included in the kit: electronic balances reading to 0.01 g or better, distilled or deionized water, small funnels, and paper towels. The kit is non-regulated for shipping.