Effect of Concentration on Osmosis

1. By: Michael Roberts Josh Kolbenschlag Brady James Taylor Rice Effect of Concentration on Osmosis

2. Step 1: Gather Materials: • 5 200 mL cups labeled 0%, 1%, 2%, 3%, 11% • Triple Beam Balance • Iodized NaCl or table salt • 5 cylindrical shaped potatoes of all same size and mass Procedure

3. Step 2: Make Concentrated Solutions • Fill a graduated cylinder with approximately 50mL of deionized water • Add the correct mass of iodized NaCl (table salt) based on percentages 0, 1, 2, 3, 11, to the water in the graduated cylinder and stir thoroughly. • Add deionized water till the graduated cylinder until it reaches 100mL • Pour the solution into the correct labeled cups • Step 3: Make Identical Potato Slices • Extract 5 cylinder shaped potato using a 5mm diameter hollow tool • Place cylinder on triple beam balance and record the mass of each. • Cut the cylindrically shaped potatoes until they are of equal mass.

4. Step 4: Place Potatoes into the Cups with Concentrated Solutions of Iodized NaCl • Place 5 cylindrically shaped potatoes into the 5 different concentrated solutions. • Step 5: Wait 30 min. • Step 6: Weigh the potatoes. • Take the potatoes out of the solutions and completely dry them off. • Mass them on the triple beam balance and record the final mass.

5. Purpose: The purpose of our experiment was to not only find the correct isotonic solution at which osmosis is at equilibrium, but to study the effects of different concentrated solutions of iodinized NaCl. • Hypothesis: Our Hypothosis was that the different concentrations of NaCl would affect the rate of osmosis in different ways. We knew that the higher concentrated the solution the more rapid diffusion of water would leave the potato cores, as well as the opposite, with the lower concetrations of solution water would diffuse into the potato cores causing them to gain weight. Our prediction on the correct isotonic solution was that at 2% the potato would be at equilibrium with the sourounding iodinized NaCl solution. Purpose and Hypothesis

6. Data:

7. Graph:

8. Based on the linear regression line from our experiment, it is possible to make the conclusion that the salt concentration of the potato equals approximately 0.5% by mass. This equals the isotonic concentration of a solution to where the mass of the potato would not change if it was placed in that solution. There is a degree of error to our experiment because the linear regression line has a r^2 value of .874, which would skew this isotonic concentration value we calculated. Graph Analysis

9. Constant variables in Experiment: • Salt (iodized NaCl) • Size, mass, and type of potato • Deionized water • Changing Variables in Experiment: • Concentration of salt Variables

10. Osmosis is defined as:Diffusion of fluid through a semipermeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration until there is an equal concentration of fluid on both sides of the membrane. In this lab we studied the effects of concentrations of iodinized NaCl and their inverse relationship of the affect of the rate of change of osmosis. We concluded that the potato had approxomitely .5% NaCl concentration by mass and the isotonic solution would be roughly the same. The affects of different concentrations was rather suddle and at higher concentrations water diffused out of the potato and at lower concentrations into the potato. Our hypothosis mirrored this with the exception that at 2% the solution was not isotonic. Conclusion