Osmosis Lab By Jake Monroe, Kristen Gray, and Krista Johnson

Background Osmosis is the diffusion of water across a permeable membrane Water will travel from a higher concentration to a lower concentration This is a type of passive transport, which means it requires no energy

Isotonic Concentrations inside and outside the membrane are equal no net movement of water equilibrium Hypertonic The concentration outside is higher than the concentration inside water will move from the inside to the outside Hypotonic Concentration inside is higher than concentration outside water moves from outside to inside osmotic pressure: if too much, the inside will burst

Purpose How does the type of solute affect rate of osmosis in both potatoes and apples?

Hypothesis We think that the potatoes and apples will lose weight, due to the fact that in osmosis, water diffuses from a higher concentration into a lower concentration. Because the solution outside of the potato or apple would have a higher concentration than the inside, we would expect the water to flow out of the potato or apple into the solution. This would mean that the potato or apple would lose weight.

Materials Needed 8 cups 4 ½ inch potato cores 4 ½ inch apple cores 400 mL of water 2.5 g of table salt 9.0 g of sucrose 4.5 g of glucose

Procedure: 1.Label cups with these labels: apple in water, potato in water, apple in salt, potato in salt, apple in sucrose, potato in sucrose, apple in glucose, potato in glucose 2.Fill the two “water” cups with 50mL of water each 3.Make salt solutions in each “salt” cup by dissolving 1.25g of salt into 50mL of water. 4. Make glucose and sucrose solutions in their respective cups by dissolving 4.5 g of sucrose into 50mL of water and 2.25 g glucose into 50mL of water. 5.Weigh the potato and apple cores and record the weights in the data table. 6.Put apple and potato cores into their solutions. 7.After 20 minutes, remove potato and apple bits. Dry off. Reweigh and record new weights in the data table.

Controls Weight Size Amount of Solute Time Temperature Variables Apple vs. Potato Type of Solute

Data Potato in Water Apple in Water Potato in Salt Apple in Salt Potato in Glucose Apple in Glucose Potato in Sucrose Apple in Sucrose Weight Before (g) Weight After (g) Change in Weight

Conclusion Our purpose was to find out how type of solute affected osmosis in both potatoes and apples. We found that all of our samples, except for one (which stayed constant), gained weight, which means that the concentration in the potatoes and apples was higher than the concentration of the solutions. This is the opposite of what our hypothesis stated.

Conclusion Possible errors with our experiment could include: not allowing for enough time, not mixing the solutions well enough, sample sizes varying, incorrect math for the molarity. If we could redo the experiment, we would allow the samples to soak for a longer period of time. We would also test more foods besides apples and potatoes, such as carrots, other fruits, and grains. Our results were not very conclusive. We learned that both the potato and apple contained a higher concentration of our solutes than what was in the outside solution. Because this was true of every sample (except for one), there was not any conclusive evidence for proving how different solutes affected osmosis. They all behaved in a similar manner. To get better results, we might think about conducting an experiment with different molarities in the outside solutions to better explain how different solutes affect osmosis.