Question

In: Chemistry

How can the iodine test be used to distinguish between starch and fructose? Why must the...

How can the iodine test be used to distinguish between starch and fructose?

Why must the Seliwanoff's test be time controlled?

Solutions

Expert Solution

Starch is polysaccharide, whereas fructose is monosaccharide.

Starch is made up of amylose and amylopectin, amylose is water soluble whereas amylopectin is water insoluble

Iodine can form inclusion compound with amylose which is blue colour, whereas fructose being monosachride does not form inclusion compound hence it is colourless with iodine

.................................................................................................

Selwinoff's test Shows positive test for: Ketoses


Reactions:

The test reagent dehydrates ketohexoses to form 5-hydroxymethylfurfural. 5-hydroxymethylfurfural further reacts with resorcinol present in the test reagent to produce a red product within two minutes (reaction not shown).

Aldohexoses react to form the same product, but do so more slowly.

Aldohexose undergo tautomerisation to ketone in acidic solution slowly so they show positive selwinoff test over longer period

half ml of a sample solution is placed in a test tube. Two ml of Seliwanoff's reagent (a solution of resorcinol and HCl) is added. The solution is then heated in a boiling water bath for two minutes.


A positive test is indicated by:The formation of a red product.


Related Solutions

Starch+Iodine are reacted to produce a Starch-Iodine complex. 10mL were then placed in 2 test tubes....
Starch+Iodine are reacted to produce a Starch-Iodine complex. 10mL were then placed in 2 test tubes. test tube one was heated to 80 degrees Celsius, and the result was a color change to yellow. testtube two was cooled in an ice water bath, and no change was observed. based on this, "Discuss how and why equilibrium was affected by each stress. be specific, inlcude the exothermicity/endothermicity of the rxn as it applies.
When determining the amount of an oxidant present by titration, you can use iodine and starch...
When determining the amount of an oxidant present by titration, you can use iodine and starch as an indicator. First, the oxidant, like hypochlorite, oxidizes Choose... neutral iodine into iodide ion iodide ion into neutral iodine iodate polyatomic ion into iodide ion . When starch and iodine are both present, the solution is Choose... blue-black brownish yellow clear . During the titration, the titrant, like thiosulfate, reduces the Choose... iodide ion into iodate polyatomic ion neutral iodine into iodide ion...
How can we distinguish between enculturation and socialisation ? Explain.
How can we distinguish between enculturation and socialisation? Explain.
Describe a chemical test that could be used to distinguish between pent-1-ene and pentane. ................................................................................................................................................ Explain,...
Describe a chemical test that could be used to distinguish between pent-1-ene and pentane. ................................................................................................................................................ Explain, using equations, the following steps in the free-radical mechanism of the reaction of methane with chlorine. •        Initiation •        Propagation •        Termination ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................
Define simple carbohydrates and complex carbohydrates, and describe how the iodine test distinguishes between them. Which...
Define simple carbohydrates and complex carbohydrates, and describe how the iodine test distinguishes between them. Which foods and products contain starchy materials? What are the ingredients of powdered sugar and the artificial sweeteners, and how do the Benedict’s, solubility, and iodine tests correlate with these ingredients?
Ions of iodine react with enzyme amylase and used as quantative test for measuring quantity of...
Ions of iodine react with enzyme amylase and used as quantative test for measuring quantity of amylase. However, ions of iodine react with enzyme amylopectin very slightly. Why.
How can Chi Square test for independence be used to evaluate test re-test reliability?
How can Chi Square test for independence be used to evaluate test re-test reliability?
How can NMR be used to distinguish the ring substitution at meta position instead of ortho...
How can NMR be used to distinguish the ring substitution at meta position instead of ortho or para nitronium attack on methyl benzoate?
Glucose, Sucrose, Fructose, and Amylose. Which carbohydrate listed can be hydrolyzed, and why?
Glucose, Sucrose, Fructose, and Amylose. Which carbohydrate listed can be hydrolyzed, and why?
Distinguish between substantive test of transaction and test of details of balance. Also provide an example...
Distinguish between substantive test of transaction and test of details of balance. Also provide an example of each for acquition and payment cycle.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT