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The purpose of this experiment is to find out what is the lowest molarity of starch which gives a positive result to the iodine test.

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Introduction

´╗┐Introduction: The purpose of this experiment is to find out what is the lowest molarity of starch which gives a positive result to the iodine test. Hypothesis: This is a simple test which shows the present of starch. When iodine solution is mixed with starch it turns from brown to dark blue. As this happens with very small amounts of starch, iodine test is a sensitive one. Starch forms as grains inside the living cells of plants. Iodine solution penetrates into the starch most easily when the cell walls have been destroyed and it reacts most readily when the starch grains are swollen. Both these things happen when plant foods are cooked. Materials: Test Tubes, Test Tube Rack, Glass Rod, Dropper, Measuring Cylinder, Water, Syringe, Iodine Solution, Starch Solution, Beaker Methods: A serial dilution of starch solution is made as follows: Place 5 clean test tubes in a test tube rack. ...read more.

Middle

This solution is now become 0.01Ùª solution. 1 cm³ solution has been transfer from the third test tube to the fourth test tube and added 9 cm³ of water to make a 0.001Ùª solution. Repeat the steps for the fifth test tube to make a 0.0001Ùª solution. 1 cm³ of this solution is now removed from the fifth test tube to make the test same. 1 drop of iodine solution is added to each test tube and stir it with a glass rod. The observation is recorded at the table 1.1. (B) Place 4 clean test tubes in a test tube rack. 2 cm³ of the starch solution has been taken out from the starch solution and place it in the first test tube by using a syringe. ...read more.

Conclusion

This is because the starch solution has been diluted for many times. Starch is a polysaccharide, consisting of glucose units joined together by glycosidic bonds. The chains formed during the condensation reaction are either linear or highly branched molecules. Conclusion: My hypothesis was stating that starch is a polysaccharide which is found in cereals like rice and in tubers like potato. Iodine test for starch is the most followed method to analyse the presence of starch in the given food material. When iodine solution is mixed with starch it turns from brown to dark blue. As this happens with very small amounts of starch, iodine test is a sensitive one. Iodine solution penetrates into the starch most easily when the cell walls have been destroyed and it reacts most readily when the starch grains are swollen. Citation: http://www.tutorvista.com/biology/iodine-test-for-starch# http://www.foodafactoflife.org.uk/attachments/92592385-dfb2-4ad6d61cf053.pdf http://www.brilliantbiologystudent.com/iodine_test_for_starch.html ...read more.

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