Benedict's test is a test used to determine the presence of reducing sugars. Sucrose is not a reducing sugar that's why its color doesn't change. . .
Benedicts solution
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)
Simply put, the products are a different color from the reactants. For example, when copper reacts with a silver nitrate solution it turns the solution from colorless to blue. This is because while the silver ions (Ag+) do not affect the solution while the copper ions (Cu2+) released by the reaction are blue in the presence of water.
The presence of a catalyst affect the enthalpy change of a reaction is that catalysts do not alter the enthalpy change of a reaction. Catalysts only change the activation energy which starts the reaction.
Adding more solute or more solvent can change a solution.
Benedicts solution
Depends on the Sugar: Reducing sugars a normally monosaccharides but there are some disaccharides too like maltose. If its a reducing sugar then you would add Benedicts Reagent (alkaline copper(II) sulphate). You then heat it. if a reducing sugar is present then a precipitate is formed that will be red/orange. A Non-reducing sugar like Sucrose can be tested by first adding benedicts and heating. if no change is present you then add hydrochloric acid to hydrolyse the glycosidic bond. you then add a hydrogen carbonate solution to neutralise the acid. Then repeating the Benedicts and Heating process.
Benedict 's solution contains Copper , which can accept electrons from reducing sugars and consequently change color. A positive Benedict's sugar test will produce an orange to brick-red color. Reducing sugars have either a free aldehyde functional group or a free ketone functional group as part of their molecular structure; starches and other polysaccharides lack these functional groups . If Benedict's test changes color ( pos. reaction ) polysaccharides must be hydrolyzed.
Benedict Solution is use to check the presence of Saccharides in food by changing the specimen's color like cooked rice when it puts a few drops of Benedict solution it change its color as yellow green. It means there is a presence of sugar in rice. About the Saliva thing, (Benedict Solution+Saliva+Cooked Rice) Saliva breaks the sugar into fragments so it helps the Benedict Solution to find the presence of sugar in rice, So it makes more yellow green than without Saliva one
there will be change in the color for iodine into blue,black because of the presence of starch in it.
there will be change in the color for iodine into blue,black because of the presence of starch in it.
there will be change in the color for iodine into blue,black because of the presence of starch in it.
there will be change in the color for iodine into blue,black because of the presence of starch in it.
there will be change in the color for iodine into blue,black because of the presence of starch in it.
there will be change in the color for iodine into blue,black because of the presence of starch in it.
Iodine turns it purple in the presence of starch. :D~PiNkBuN17 Aka Aisha
An enzyme.