Determining Diffusion: How Concentration Affects the Rate of Diffusion Across a Cell Membrane

Lawrence Schaeffer, Tristen lee, Jeremy Kaplan


This experiment was performed in order to see if there is a correlation between aqueous salt concentration gradient on either side of a semipermeable membrane and the rate diffusion of that salt. We hypothesized that a higher concentration on one side of the membrane, compared to the other side, would increase the rate of the diffusion of the salt out of the membrane. Although some research has already been conducted in terms diffusion across a gradient, much of that research lacks the inclusion of the diffusion across a semipermeable membrane. Experiments on semipermeable membranes and diffusion go back to the 1950s, such as Eugene Renken’s with pig intestines, but experiments since then have been few and far between. For our experiment, we performed six separate trials of 3 differently concentrated solutions in dialysis tubing. The rate at which the aqueous salt solutions diffused out of the cells was recorded with a conductivity probe. Artificial membranes such as dialysis tubing can be used in many lifesaving medical procedures and any added research in the field, such as ours, is beneficial to many people.  

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