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Life asked in Science & MathematicsChemistry · 5 years ago

Mix iodine with starch. Anyone with knowledge?

I got this lab report for school who is due tomorrow morning so i'm seeking for a quick answer if possible.

A. Starch + iodine; which gave blue colored solution

B. Saliva + starch + iodine solution; resulting colorless solution

C. Saliva was boiled for 10 minutes then added starch + iodine; which gave blue colored solution

D. Saliva + starch + iodine in acid solution; which gave blue colored solution

E. The D tube was added an alkaline solution so that the solution became neutral; the blue color disappeared and the solution became colorless

Why is it that some of the tubes turn blue and some doesn't?

1 Answer

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  • hcbiochem
    Lv 7
    5 years ago

    Any time you combine starch and iodine the two react to form a blue color.

    In tube B, an enzyme in saliva breaks down starch into sugar. Iodine no longer has starch to react with, so there is no blue color produced.

    In C, the enzyme is inactivated by heating it, so it can no longer break down the starch. Since the starch remains, iodine forms the blue color.

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