The Benedict’s test for reducing sugars Flashcards

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1
Q

Benedict’s test is for

A

reducing sugars

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2
Q

What is benedict’s reagent

A

is a blue solution that contains copper (II) sulfate ions (CuSO4 ); in the presence of a reducing sugar copper (I) oxide forms

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3
Q

Copper oxide is not soluble so it forms

A

so it forms a precipitate

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4
Q

First steps of benedict’s test Add Benedict’s reagent (which is blue as it contains copper (II) sulfate ions) to a sample solution in a test tube heat the……..

A

Heat the test tube in a water bath or beaker of water that has been brought to a boil for a few minutes

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5
Q

What happens if a reducing sugar is present

A

If a reducing sugar is present, a coloured precipitate will form as copper (II) sulfate is reduced to copper (I) oxide which is insoluble in water

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6
Q

Why is it important to put a excess of benedict’s solution

A

It is important that an excess of Benedict’s solution is used so that there is more than enough copper (II) sulfate present to react with any sugar present

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7
Q

A positive test result is a

A

colour change somewhere along a colour scale from blue (no reducing sugar), through green, yellow and orange (low to medium concentration of reducing sugar) to brown/brick-red (a high concentration of reducing sugar)

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8
Q

Why is this test semi quantative

A

This test is semi-quantitative as the degree of the colour change can give an indication of how much (the concentration of) reducing sugar present

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9
Q

What are the reducing sugars

A

galactose

fructose

glucose

maltose

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10
Q

non reducing sugars

A

sucrose

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11
Q
A
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