What is the color of the initial iodine test on starch solution?
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The iodine test is a chemical reaction used to detect the presence of starch in a solution. Show more…
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Iodine Test for the Presence of Starch Starch is a long polymer consisting entirely of glucose (a monosaccharide). Starch is the major nutrient storage polysaccharide in plants and their seeds. Starch itself is composed of subunits of small polysaccharides (amylose and amylopectin), which in turn are composed of chains of glucose molecules. Iodine solution contains iodine and potassium iodide. The coiled structure of the polysaccharide starch produces a dark blue-black color in the presence of iodine, which is usually yellow to brownish in color. Because this reaction does not occur with monosaccharides or disaccharides, the blue-black color is considered to be positive for starch. Demonstration of Iodine Test: Iodine Starch Iodine Procedure for Iodine Test: Label four test tubes and place 2 ml of the following solutions in the corresponding tubes: - 1% glucose - 1% sucrose - 1% starch - 1% distilled water (DI H2O) Add 2 ml of iodine solution to each tube and mix; note the color change in the following chart: Tube | Contents | Color | Results | Conclusions 1 | Glucose | orangeish | - | 2 | Sucrose | orangeish | - | 3 | Starch | Black | + | helical structure of Starch 4 | DI H2O | orangeish | - | What was the purpose of the distilled water in each test?
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what color is the Iodine Aolution
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