How Salt Concentration Affects Rate of Diffusion Across a
Cell Membrane
By Dylan Purcell
2/17/15
Biology 1
Period 5

Introduction and Hypothesis The overall purpose for this experiment was to graph and observe how the salt concentration affects the rate of diffusion in a cell by using a larger representation as an accurate model. This will show how a cell would react when put into water with a lower salt concentration than what is inside the cell.
The expected results were very accurate to the found data, as it showed the rate of diffusion was very significant in the different solutions. The information shown on the one­percent salt solution had a rate of diffusion of 0.67151. The data found on the five­percent salt solution showed a rate of diffusion of 2.5594. The rate of diffusion in the ten­percent salt solution was 3.8355. The rate of diffusion increases with a larger amount of salt in the solution. The information that was found supported the idea that if a cell is put into a solution that was put into a solution with a higher salt concentration than what the cell contains, then the water will diffuse across the cell membrane, because the water concentration will be different, which is why water will diffuse across the membrane.
If the cell is placed in a solution that has a different water concentration outside than inside the cell, then the water will diffuse across the cell membrane, because otherwise the water concentration will be irregular.

Results Rate of Diffusion in Varying Salt Concentrations
Salt Concentration in Water

Rate of Diffusion

1%

0.67151

5%

2.5594

10%

3.8335

This data table shows the rate of diffusion for each salt concentration. The rate of diffusion is highest with ten­percent salt concentration, and is lowest with one­percent salt concentration. This supports my hypothesis by showing how the rate of diffusion is directly affected by the salt concentration.
The graph shows a large spike of speed in the rate of diffusion with the individual salt solutions. This is also shown in the data table. With the one­percent salt

concentration the rate of diffusion is very low and with the ten­percent solution the rate of diffusion is high. This further supports my hypothesis.

Analysis The basis of this experiment was to show the rate of diffusion in a cell when it contains a certain salt concentration. If a