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Anonymous users2024-02-08If you add saliva, there is salivary amylase in the saliva, which will turn all the starch into maltose, so as long as the total amylase in the saliva is active and the reaction time is long enough, then it will not turn blue.
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Anonymous users2024-02-07Adding iodine without water will also turn blue.
A solution is formed.
Starch undergoes a chemical reaction with elemental iodine.
Makes the solution change from colorless to blue.
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Anonymous users2024-02-06It doesn't have to turn blue, it may be brown.
If the starch is straight-chained, it appears blue.
Those with branched chains are brown.
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Anonymous users2024-02-05You can try it, natural science is based on experiments. And starch and water are there in life.
It may turn blue or purple, depending on the molecular structure of the starch.
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Anonymous users2024-02-04The starch turns blue when exposed to iodine.
In fact, any chemical reaction is the result of mutual interaction. Starch turns blue when exposed to iodine because the starch molecules and iodine molecules form a complex, which reflects and absorbs light at different wavelengths differently, resulting in a blue appearance.
It is not that one of the two substances changes color on its own, or that A changes color to B, but that both change color together, or that this change is the result of the combined action of the two substances.
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Anonymous users2024-02-03Starch will undergo a chemical reaction when it meets iodine to form starch iodide, which appears blue. To prove that starch turns blue when exposed to iodine, the following experimental steps can be performed:
Material: starch solution.
Iodine solution. Steps:
Take a small amount of starch solution and put it into a test tube.
Add a small amount of iodine solution and stir well.
Observe the color change of the starch solution in the test tube, if it appears blue, it proves that the starch turns blue with iodine.
This is due to the fact that the starch molecule contains a large number of glucose groups, and a part of the hydroxyl group can form a complex with iodine, that is, starch iodide. The molecular structure of starch iodide is similar to that of iodine molecules, and it can absorb the blue wavelength of visible light, so it appears blue.
It is important to note that this experiment should be conducted in a laboratory or science teaching place, and it should be handled safely. In addition, the appropriate amount of reagents should be used in the experiment to avoid waste and contamination.
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Anonymous users2024-02-02Amylose, dissolved in water, is in a curved form and is coiled into a helix shape by intramolecular hydrogen bonds. Iodine is added, in which the iodine molecule burrows into the void in the spiral and is linked to amylose with the help of van der Waals to form a complex. This complex can absorb other visible light (wavelength range 400-750 sodium rice twigs) except blue light relatively evenly, so that the starch becomes dark blue.
Starch is a plant polysaccharide that is formed by the dehydration and condensation of hundreds to thousands of glucose monomers. It is usually composed of two parts: amylose and amylopectin. Amylose is soluble in hot water and has a smaller molecular weight than amylopectin; Amylopectin is insoluble in cold water, and will form a paste when it reacts with hot water, and its molecular weight is larger than that of amylose.
The reason why starch and iodine will have a color reaction is due to the fact that iodine molecules enter the spiral circle of starch and form starch-iodine complexes. As for what color it appears, it is related to the length of the starch sugar chain. When the chain length is less than 6 glucosyls, it will not be colored; When the average length of the chain length is 20 glucose groups, it will be red; When it is greater than 60 glucosyl groups, it is blue.
The principle of iodine turning blue when it meets starch is that the essence of the reaction between starch and iodine is to form a kind of inclusion complex, which makes the color blue.
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