A certain amount of white solid was dissolved in enough water and gives a colorless solution.  A portion of the solution was added with 15% solution of  alpha-naphthol solution and a few drops of conc. H2SO4 forming a violet-colored  ring.  Another portion was added with drops of Seliwanoff’s reagent and showed no change after being warmed in a bath.  Another portion was added with equal amounts of Fehling’s A and B reagent giving a red precipitate in a blue solution after warming in a bath.   a)  Cite an experimental result confirming that the solid is a carbohydrate  b)  Is the solid starch, fructose or glucose?  Support your answer.

Biochemistry
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Chapter1: Biochemistry: An Evolving Science
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A certain amount of white solid was dissolved in enough water and gives a colorless solution.  A portion of the solution was added with 15% solution of  alpha-naphthol solution and a few drops of conc. H2SO4 forming a violet-colored  ring.  Another portion was added with drops of Seliwanoff’s reagent and showed no change after being warmed in a bath.  Another portion was added with equal amounts of Fehling’s A and B reagent giving a red precipitate in a blue solution after warming in a bath. 

 a)  Cite an experimental result confirming that the solid is a carbohydrate

 b)  Is the solid starch, fructose or glucose?  Support your answer. 

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