The Effect of Temperature on Diffusion Rate Through a Semi-Permeable Membrane

Thomas Hess, Caleb Jones, Corban Hemphill, Kaytlyn Goodwin


For this experiment we attempted to determine the relationship between the rate of diffusion of a solution through a semipermeable membrane and the temperature of the solution.  Our hypothesis about this relationship was that as the temperature of a given solution increases, the rate of diffusion through a semipermeable membrane will also increase, because the amount of thermal energy present in the solution is directly proportional to the rate of diffusion.  On a molecular level this thermal energy will present itself as the molecules present moving with greater velocity and more vibrational motion when more thermal energy is present than when there is less.  This greater velocity means that, in theory, the particles should come into contact with the membrane wall more often, and with greater force, making the molecules move through the membrane at a faster rate.  In our research we came across a study done by Inselsbacher and Näsholm which found that as temperature of soil decreases, the diffusion of plant available nitrogen through soil slows down (Inselsbacher and Näsholm, 2012).  We believe this study is not sufficient to determine the relationship between the rate of diffusions through our dialysis tube and temperature because soil is innately heterogeneous, while our dialysis tube is homogenous throughout.  To tackle the problem we measured the electrical conductivity of a solution over time as a packet of 1% g/mL aqueous NaCl solution was inserted into a beaker of pure deionized water.  The implication of this research would be to give us an idea of the optimal temperature to use the membrane the corporation wants us to test.

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