iodine is an indicator for starch, potatoes are basically starch storage organs for potato plants. that's why they are good to eat, mmm starch!
Iodine is used to find starch. If no starch is present, a rusty brown color will appear. If starch is present like in bread and potato, the iodine when put on will turn blackish blue. That is known as a chemical reaction. Since there is no starch in water, the iodine in the water stays the same color as it started (brown). Hope that helps!! :)
When iodine comes into contact with starch, it forms a blue-black complex. Therefore, if you were to apply iodine to a cut onion, the starch present in the onion cells would react with the iodine, turning the onion a blue-black color. This color change is a common test for the presence of starch in biological samples.
dark blue - purple
The color remain red because vinegar is an acidic solution.
Only if the color change is not permanent. Take Iodine for example (that's pronounced Eye-oh-deen), it is a solid metal that is grayish in color in its solid state, however in its gas state it's a purple or violet color. Once it reverts to its solid state, it turns gray again. This is a PHYSICAL property of Iodine. If the color changed permanently to something else, it would be a chemical change.
iodine solution
A dark blue/black color develops when iodine solution is added to starch solution. This color change occurs due to the formation of a starch-iodine complex, where the iodine molecules interact with the helical structure of the starch molecules, resulting in the blue/black color.
When Lugol iodine solution is added to potato cells, the starch granules present in the cells appear dark blue or black due to the formation of a starch-iodine complex. This color change is used as a test to detect the presence of starch in cells.
The color change that occurs when iodine solution is added to starch is a dark blue or purple color. This reaction is commonly used to test for the presence of starch in a solution.
If iodine solution is added to a leaf, it will turn blue-black in color. This is due to the presence of starch in the leaf which reacts with iodine to produce this color change.
Crisps are made from potatoes which are very high in starch. When iodine is added to starch it forms a complex with it and results in a purplish color. you get the same thing if you put an iodine sol'n on bread or cornstarch.
Iodine tests for complex sugars. Glycogen is a complex sugar and will change dark purple when iodine solution is added (color is irrelevant, all you really need to know is that the change to a specific color signifies a presence of a macro molecule)
Iodine turns blue-black when added to a protein solution such as starch. This color change indicates the presence of complex polysaccharides like glycogen or amylose.
The blue-black color is likely due to the presence of starch in the potato. Iodine reacts with starch to form a blue-black complex. This test is often used to detect the presence of starch in a solution or sample.
If you add iodine to a potato, the iodine will react with the starch present in the potato. This reaction will result in a color change, turning the potato a blue-black color where starch is present. This can be used as a test to detect the presence of starch in foods.
If the iodine on/in the potato turns dark blue/purple/black, it means the iodine has reacted to the starch in the potato and has changed color.
iodine is soluble in CHCl3. Liquid become purple in color.