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The Effect of the Type of Bag on the Rate of Diffusion

The Effect of the Type of Bag on the Rate of Diffusion. Nick Gude Period 3 M. Pietrangelo. Problem Statement and Hypothesis. Which brand of bag will have the slowest diffusion rate?

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The Effect of the Type of Bag on the Rate of Diffusion

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  1. The Effect of the Type of Bag on the Rate of Diffusion Nick Gude Period 3 M. Pietrangelo

  2. Problem Statement and Hypothesis • Which brand of bag will have the slowest diffusion rate? • Will the results prove significant enough to be able to claim that that brand(s) has the best plastic content? • If different brands of bag are used then they will have different amounts of time for diffusion to occur. • Prediction • Ziploc-Slowest Rate • Giant-Normal Rate • Hefty-Fastest Rate

  3. Basic Concepts • Diffusion: the primary method of short distance transportion in a cell and cellular systems; a cell’s means of transporting things such as food to and from other cells (Ordom, McCandless). • Materials pass through pores in the membrane from high to low concentration. • Indicator: usually visual sign that change has occurred in an experiment.

  4. Design Diagram • IV: Brand of Bag • DV: How long (in minutes) it takes for the starch in the bag to diffuse with the iodine solution outside. • Constants: room temp., container size, plastic bag size, amounts of iodine and starch solutions for each trial. • Materials: Ziploc, Giant, and Hefty bags, three glass bowls, graduated cylinder, water, cornstarch, iodine, transfer pipette, timer.

  5. Design Diagram cont. (Procedure) • In each bowl: 1L of water + 20 ml of iodine. • In each bag: two tsp. starch and fill bag halfway with water. • Put one of each brand with added ingredients into its respective bowl. • Start timer and observe. • Once evidence of diffusion is seen (a purplish-black color), record the time for that trial in data table. • Ten trials for each brand.

  6. Results: Data

  7. Average Diffusion Rates • Ziploc: Sum of all trial times divided by number of trials (10) = 31m 32s avg. • Giant: Sum of all trial times divided by number of trials (10) = 19m 30s avg. • Hefty: Sum of all trial times divided by number of trials (10) = 10m 7s avg.

  8. Graph of Diffusion Rate Averages 31m 32s 19m 30s 19m 7s

  9. Statistical Analysis • 2 Sample T-tests were used to determine if the results of the experiment were significant. • Ziploc T Tests to both Giant and Hefty both resulted in low probability of chance (p < .0001) • The results were significant, and it could be claimed that Ziploc will always have a slower diffusion rate than the other two.

  10. Statistical Analysis cont. • Based off the information gathered from the results of the experiment, it is safe to say that the original hypothesis that each bag would have a different diffusion rate is rejected, since although Ziploc’s time was proven to always be slower, Giant and Hefty could go either way.

  11. Me with my materials, 11/4/10

  12. Me starting the first trial, 11/13/10

  13. Me holding up a diffused bag, 11/14/10

  14. Results Explanation • The diffusion rate is related to the number and size of the pores in each bag brand. • Ziploc had a slower diffusion rate, therefore less or smaller pores in the plastic. • Hefty and Giant had relatively equal diffusion rates, therefore a relatively equal size and amount of pores.

  15. Sources of Error • Not refilling the bowls with fresh iodine for every trial could have slowed down the diffusion time for a few trials. • The bowls were not completely identical, and this could have affected the diffusion rate. • Iodine to size of bag ratio: experiments found online used smaller, thinner sandwich bags, which could have slowed down what would have been the regular diffusion rate for the bags.

  16. Possible Improvements/Extentions • For each trial, use a freshly mixed iodine and water solution. • Submerge each bag as much as possible, perhaps get deeper containers. • Using more iodine in the solution to compensate for the type of bags used.

  17. Applications • Model/Simulation of simple cellular diffusion. • Used by many schools already for exactly that purpose. • Could perhaps influence people’s decisions about which brand of plastic bag is best, maybe an indicator that Ziploc has better quality plastic.

  18. Acknowledgements/Thank You’s • Parents • Miss Pietrangelo • The people who accepted my project • And YOU

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