Comparing Amount of Glucose in Orange Fruit, Grapefruit and Lemon Fruit

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Comparing Amount of Glucose in Orange Fruit, Grapefruit and Lemon Fruit

I have been given 4% of glucose solution, benedict's solution and

distilled water to find out the concentration of glucose of these

three juices; orange, lemon, and grapefruit.

The method of serial dilution has to be done to work out the

concentration; this is because the concentration of glucose is far too

concentrated. A dilution factor has to be worked out; I will be using

a dilution factor of 5, which means the amount of glucose and the

percentage of glucose will always divide by 2 as the dilution solution

carries on.

Theory

Orange, lemon and grapefruit are all fruits which contain

carbohydrates which include reducing sugars. Glucose is a hexose

sugar, which is a monosaccharide with six carbon atoms in each of its

molecules.

Benedict's solution is a deep-blue alkaline solution used to test for

the presence of the aldehyde functional group, CHO - which are present

in reducing sugars. Benedict's solution changes colour when a reducing

sugar is present because of a chemical reaction, which reduces the

Copper II sulphate (which is soluble) to copper I oxide, which is

insoluble and produces a precipitate. The benedict's solution changes

colour from blue to green, yellow, orange, brown and finally red - as

the amount of sugar increases.

Colorimeter

Instruments for the analysis of coloured solutions include the

colorimeter. In both these instruments, light emitted from a source

passes through the sample to be analysed, and the intensity of the

emergent beam is measured by a photoelectric device and recorded on a

milliameter. The wavelength...

... middle of paper ...

... 8.75

0.5

5

0.6 (0.625)

9.4 (9.375)

0.25

6

0.3 (0.3125)

9.7 (9.6875)

0.125

Grapefruit Juice

Test tube

Glucose ml

Distilled water ml

Glucose %

Colour Transmission

Glucose Concentration

1

10

-

4

2

5

5

2

3

2.5

7.5

1

4

1.25

8.75

0.5

5

0.6 (0.625)

9.4 (9.375)

0.25

6

0.3 (0.3125)

9.7 (9.6875)

0.125

Orange Juice

Test tube

Glucose ml

Distilled water ml

Glucose %

Colour Transmission

Glucose Concentration

1

10

-

4

2

5

5

2

3

2.5

7.5

1

4

1.25

8.75

0.5

5

0.6 (0.625)

9.4 (9.375)

0.25

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