The rate of diffusion of a salt solution through a membrane is investigated under different conditions of concentration.

Description
KEBS4A provides the tools for data collection that will enable investigation of rates of diffusion through a membrane under different conditions.

Principle
Diffusion is a process that allows ions or molecules to move from where they are more concentrated to where they are less concentrated. This process accounts for the movement of many small molecules across a cell membrane. Diffusion is the process by which cells acquire food and exchange waste products.
One way to measure the rate of diffusion of ions is to monitor their concentration in solution over a period of time. Since ions are electrically charged, water solutions containing ions will conduct electricity. A Conductivity Probe is capable of monitoring ions in solution. This probe however, will not measure the amount of electrically neutral molecules dissolved in water.

Tasks
• Use a computer and Conductivity Probe to measure the ionic concentration of various solutions
• Study the effect of concentration gradients on the rate of diffusion

Ideas for Extended Investigations
1. Design an experiment to determine the effect of temperature or other variables on the diffusion of salt. Perform the experiment you designed.
2. Investigate rates of diffusion for different types of solutions. Relate diffusion rates to shape and size of molecules present.

Last edited 22nd Aug 2018