Page 99 - Biology - XII

Test Tube Inverted Test Tube

5 ml extract of
green leaves
+ 5 ml Benzene Dark green layer
+ 1 ml water

Thumb Pale yellow layer
(a) (b) (c)

Fig. 3.2: Separation of layers of pigments

Results
1. Two distinct coloured layers are formed.
2. The top dark green benzene layer has chlorophylls (a and b) and lower alcoholic layer has yellow
xanthophyll.

Observations
Separation of chlorophyll solution by benzene
S. No. Experiment Observation Inference

1. In a clean and dry test tube, take 5 ml two distinct layers
of alcoholic extract of green leaves + are formed.
5 ml benzene + 1 ml water. (Invert the
contents by putting your thumb on the Green layer Chlorophyll is present.
mouth of the test tube many times.) Yellow layer Xanthophyll is present.

Conclusion
Chlorophyll solution has diff erent pigments.

C. SEPARATION OF YELLOW AND GREEN PIGMENTS

Objective
To separate yellow and green pigments.

Materials Required
Fresh green leaves, mortar and pestle, ether, 30% KOH, methyl alcohol, and test tubes

Procedure
1. Make ether extract of chlorophyll by crushing small pieces of fresh green leaves in a mortar with sand.
2. Filter out the extract to obtain a clear liquid/fi ltrate.

3. Take 1 ml of extract+ 0.5 ml of 30% KOH in pure 1 ml methyl alcohol.

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