negative
Starch, I think, because iodine solution is the test for starch.
The Iodine test uses Iodine solution, which is usually a brown colour. It is used to test for the presence of Starch. Iodine solution, iodine dissolved in an aqueous solution of potassium iodide, reacts with starch producing a blue black color. If the sample being tested doesn't turn blue-black, then starch isn't present.
Starch is composed of amylose and amylopectin, and is not soluble in water due to the presence of amylopectinIodine (I₂) is somewhat soluble in water, but is more soluble in iodide (I⁻) solutions, such as potassium iodide solution (KI).Aqueous iodine molecules (I₂) and iodide ions (I⁻) together will form triiodide ions (I₃⁻), which can react with amylose found in starch to produce a deep-blue colour in the solution. So all of iodide (I⁻), iodine (I₂) and amylose (or starch) are required together to produce the colour.This can be used to test for:Amylose/Starch: Add iodine dissolved in potassium iodide solution to test solution, orIodine: Add starch and potassium iodide solutions to test solution.If the substance being tested for is present, then triiodide ions (I₃⁻) can react with amylose (in starch) to produce a deep-blue colour, that is, a positive result.
This solution is acidic.
Carbohydrates, especially starch, which is a polysaccharide carbohydrate. Starch turns deep purple when tested with iodine.
It change from orange/brown colour to blue/black if starch is present
Starch, I think, because iodine solution is the test for starch.
The Iodine test uses Iodine solution, which is usually a brown colour. It is used to test for the presence of Starch. Iodine solution, iodine dissolved in an aqueous solution of potassium iodide, reacts with starch producing a blue black color. If the sample being tested doesn't turn blue-black, then starch isn't present.
Iodine solution turns blue/black
By dissolving the pH solution a colour change will occur in the solution that should be tested.Compairing the colour of solution to the colours marked on of pH chart we can find out if the solution we tested is of alkaline nature or of acidic nature or neutral.Solutions of pH7are neutral solutions.Solutions below pH7 are acidic solutions and those above pH7 are alkaline solutions.
The presence of starch can be tested with the help of Iodine. Similarly Benedict's test solution is also used to detect the presence of starch.
the iodine stayed orange because the starch wasn't present
It depends if it is starch, yes. Other sugar, NO!
This phenomena depends upon the what is tested. iodine test usually gives a positive result of blue color for starch. The blue color is caused by the trapping of the iodine inside the structure of the starch (note that starch is a polyssacharide that has a helical structure). It is only with starch that this happens cause starch has the only one with a helical structure. Now your question is why is it that the color disappears when heated, right? This is because the heat causes an unwinding of the helical structure of starch releasing the trapped iodine making the solution colorless. However, if cooled, with no heat present, the starch structure becomes helical once more trapping the iodine returning the blue colored solution. this is just what i learned from my Biochemistry class, hope it helps!!
Both cows milk and water-buffalo's milk produce a violet colour when tested with biuret solution because they both contain protein.
Starch is composed of amylose and amylopectin, and is not soluble in water due to the presence of amylopectinIodine (I₂) is somewhat soluble in water, but is more soluble in iodide (I⁻) solutions, such as potassium iodide solution (KI).Aqueous iodine molecules (I₂) and iodide ions (I⁻) together will form triiodide ions (I₃⁻), which can react with amylose found in starch to produce a deep-blue colour in the solution. So all of iodide (I⁻), iodine (I₂) and amylose (or starch) are required together to produce the colour.This can be used to test for:Amylose/Starch: Add iodine dissolved in potassium iodide solution to test solution, orIodine: Add starch and potassium iodide solutions to test solution.If the substance being tested for is present, then triiodide ions (I₃⁻) can react with amylose (in starch) to produce a deep-blue colour, that is, a positive result.
polysaccharides and simple sugar