Because iodine molecules enter glucose molecules, the intermolecular force (valence bond force) makes them closely combined, and this structure makes light scatter (physical reasons) when it passes through molecules and turn blue.
Add starch paste to clear water and stir, then add saliva and stir. Finally, add iodine to show what color. If the amount of saliva is enough, amylase will promote starch decomposition, and after adding iodine, there will be only the color of iodine. If there is not much saliva, iodine turns blue when it meets starch.
Why does iodized salt turn blue when it is dissolved in water, added with starch solution of KI, and then added with acidic reagent? Iodine in iodized salt is positive, KI is negative, reducing, and iodine is generated by oxidation-reduction reaction, which is purple.
Add starch to the test tube, then add saliva, and then add dilute iodine solution, will it turn blue? Is there any difference between dilute iodine solution and iodine solution? Not in theory. Saliva has salivary amylase which can hydrolyze starch.
Dilute iodine solution is the same as iodine solution. Because iodine has little solubility in water, it is a dilute solution.
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What is the phenomenon of adding dilute sulfuric acid to iodine ions and then adding starch? The conditions of ionic dissociation of iodate in electrolytic solution zone can cause oxidation reaction. The experiment of iodine simple substance starch solution turns blue when it meets iodine: take a small amount of electrolyte in anode zone, add dilute sulfuric acid and add a few drops of starch solution to observe whether it turns blue; The iodine-containing ion in the anode area turns blue by adding dilute iodine sulfate, otherwise it will change color.
Therefore, the answer: take a small amount of electrolyte in the anode area and add dilute sulfuric acid to acidify it in a test tube, and add a few drops of starch solution to observe whether it turns blue; Blue means I- blue means I-
Don't think that such questions are meaningless.
Many troubles are found by ourselves.
Starch will turn blue when it meets iodine. What can be changed back by adding sulfur dioxide?
Adding hypochlorous acid
Adding Na2S solution to AgNO3 solution produces _ _ _ _ _ _ color precipitate, then adding KI solution, the precipitate becomes _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
So the answer is: white; Yellow; Black.
Put rice in a glass of water and add iodine. Why does rice turn black and be oxidized?
In the following experiments, the obvious color change is that dilute sulfuric acid B is added to starch A solution, concentrated nitric acid C is added to egg white, and iodine A is added to starch solution. Without reaction, concentrated sulfuric acid can carbonize sucrose to black.
B, protein will denature and turn yellow, which is called protein's color reaction.
C, turn blue
D, brick red precipitate will be generated after heating. Generally, after the hydrolysis of starch and cellulose, alkali needs to be added to neutralize the acid in the original solution, so as to avoid copper hydroxide from being reacted by the acid, and it is directly a glucose solution, which can be omitted.
I hope it will help you, please adopt it if you are satisfied, dear!
Dear, the answer I said is BCD. To be honest, I always thought the topic was wrong, so I chose the one that doesn't change color.
Adding iodine water into feso4 solution does not fade, but after adding NaHCO3, the iodine water fades. Why I2+H20 = hi+hio, hi+HCO3-= I-+H2O+CO2 gas symbol, and the addition of nahco3 makes the reaction between iodine and water move forward, so it fades!