Lauren Bracchi Lauren Elvig Kevin Mackin Aaron Boyd

Problem How do various factors affect the osmosis of water in an apple core? Our specific problem was how does the change in concentration of the solution affect the osmosis of water in an apple core.

Background Information Osmosis is a type of passive transport of molecules through a membrane, it is the diffusion of water through this membrane. To put it in more specific terms, it is the movement of water from a lower concentration of the solute to a higher concentration of the solute.

Hypothesis If we increase the concentration of the solute, dextrose, then the solution will become hypertonic and the apple core will lose weight.

Procedure Come up with different concentrations for the solution, in our case different amounts of dextrose (distilled water, 2%, 4%, 6%). Obtain 4 apple cores of the same size and take an initial mass. Record. Make the first solution by simply measuring 100 mL of distilled water in a graduated cylinder and then putting it in a cup. Make the next solution by measuring out 50 mL of distilled water in a graduated cylinder and adding 2 grams of dextrose. Mix and stir until dissolved, then add more distilled water until the solution reaches 100 mL. Put it in a cup Repeat this step for the other concentrations, using 4 grams of dextrose for 4%, and 6 grams of dextrose for 6%.

Put the apple cores in their respective cups, (make sure you know which mass goes with which apple core), and wait for 30 minutes to let the osmosis occur. When the 30 minutes is done, take out the apple cores and pat them dry to get all the extra water droplets off the outside. Then take the final mass of the apple cores. Find the molarity of the different solutions by taking the mass of the solution that we put in the distilled water and dividing it by the molar mass, then divide it by the amount of solution (.1 L) Also find the % mass change, which is the final mass-the initial mass and divided by the final mass.

Data Distilled Water 2% dextrose4% dextrose6% dextrose Initial Mass4.61 g4.48 g3.4 g4.75 g Final Mass4.8 g4.5 g3.4 g4.6 g Molarity0.111 M.222 M.333 M % Mass Change.039%.0044%0%.032%

For the distilled water everything went according to plan and the apple core gained weight because there was more sugar in the apple core, so the water diffused into the core. For the concentration of 2%, the mass of the apple core increased as well, however it did not increase as much as in the distilled water. In the cup of 4% concentration of dextrose, we observed that there was no noticeable change in mass, which means that it reached an isotonic state. In the cup of 6% we found that the mass of the apple core decreased in mass, because the outside solution was hypertonic and the apple was hypotonic, so osmosis occurred out of the core.

Conclusion The purpose of this lab was to find out how different factors affect the osmosis of water, and in our specific case it was how the concentration of the solution affects the osmosis. In our lab we found that for the distilled water the mass increased from 4.61 g to 4.8 g because the apple was hypertonic and the outside solution was hypotonic, so the water diffused into the apple We found that for the 2% solution the apple also gained mass, from 4.48 g to 4.5 g, though not as much as the distilled water, but for the same reasons For the 4% solution, there was no visible change in the mass of 3.4 g because the solution had reached an isotonic state. And finally for the 6% solution, the apple lost mass, from 4.75 g to 4.6 g because there was more dextrose in the outside solution (hypertonic), and less dextrose in the apple (hypotonic), so the water diffused out.

Our data agrees with our hypothesis because we predicted that as the concentration of the solution increased, then the outside solution would become hypertonic, and water would diffuse out of the apple core, and so the core would lose mass. Our data proves this because as the concentration went up, the mass of the apple went down.

An error that could have occurred is when the apple cores were put in at different times, which would have caused inaccurate data if not timed. Another error that could have occurred is the solutions could have been contaminated, and this would also cause inaccurate data.

If we were to change anything we would have made all of the apple cores the same size. The reason for this is it affects the apple cores differently if they are different sizes due to more mass and surface area. Another thing we would have done differently is we would have put the apple cores in at the same time. We put them in at different times not keeping track of the time. So we guesstimated instead of timing. Which caused us to have inaccurate data.

We learned about Osmosis in this lab. This relates to what we are doing because we are, in fact, learning about osmosis in class. We found out that and apple is 4% concentration dextrose. We found this out when we put the apple core in the 4% dextrose solution and the apple didn’t change weight after 30 minutes of sitting in it. It reached an isotonic state. After the 4% was the 6%, and that apple core lost weight which means that the concentration outside of the apple core was greater then the apple core.