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Diffusion of Iodine and Starch through the Semi-Permeable Membrane of a Visking Tubing.

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Introduction

´╗┐Diffusion of Iodine and Starch through the Semi-Permeable Membrane of a Visking Tubing. Aim To explore Diffusion across a Semi-Permeable membrane Hypothesis The Aim of the hypothesis is to explore whether large starch molecules are too large to pass through the semi-permeable membrane, but iodine is small enough to pass through the membrane, in this experiment it will be looked to investigate if the Visking Tubing will change a different colour, as the Iodine moves through the Semi-Permeable membrane into the starch molecules this is believed as Iodine reacts with Starch and changes colour. Materials used: 1. Bunsen Burner 2. Heatproof Mat 3. Tripod 4. Gauze 5. Beaker 6. Visking Tubing 7. Stirring Stick 8. ...read more.

Middle

5. Once clear remove the beaker from the heat and allow cooling for approximately 10 minutes. 6. Whilst allowing the solution to cool, fill another beaker with 200mls of Water. 7. Tie a knot at one end of the Visking Tubing and rinse under water to ensure it is clean; lightly rub the top to gently open the Visking Tubing. 8. Using a pipette, fill the Visking Tubing with the cooled down Starch Solution and tie a knot in the top of the Visking Tubing, ensure the outside remains clean for fair results. 9. Place the Visking Tubing into the Beaker of 200mls of water and add 10 drops of Iodine Solution or until the water is yellow. ...read more.

Conclusion

This shows that the Starch Molecule could not pass through the Semi permeable membrane as it was too large and the Iodine which is an atom was small enough to pass through the membrane to react with the Starch which caused the colour change as the results shown. The hypothesis is accepted. Substances consisting of small molecules can move across the semi-permeable membrane (Visking tubing). Evaluation If the experiment were to be carried out again there are certain things that could be changed these could include: 1. The amount of Iodine drops used. 2. Checking temperature accurately. 3. Using stopwatch to record times. 4. Use the same amount of Starch Solution in each Visking Tubing. ________________ Michelle MilburnPage ...read more.

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