GETTING ON WITH ENGLISH IN THE LAB 2n ESO;Extraction of chlorophyll pigments

                                         

;

 The following procedure is used by chemists to know which substances are in certain products.

It is called chromatography, due to the coloured bands that  are obtained in the experience.

 Each color is characteristic of a substance, 

This technique allows determining the kind and amount of substances.

In this case try to see the pigments that are in green leaves.

1. Mash  the green leaves in a mortar , which may be for example, spinach, chard ...2. Add a little alcohol and continue crushing the mixture. (The amount of alcohol should be small).3. Filter the liquid obtained and collect it in a test tube. • This solution contains the chlorophyll.4. Take a narrow strip of filter paper, approximately 0.5 cm wide. Put a drop of the liquid obtained in  the end of the strip,  Let it dry.Then add another small drop.You will obtain a small  and concentrated stain.5.Then, put the paper strip into a test tube, Pour about 2 cm³ of  solvent. Do it as indicated by the picture below, so that the stain is a centimeter above the level of the solvent.                    
        
6. After a while, by  capillarity  the solvent will go up through  the filter paper, dissolving the green stain  and forming bands of color.The chromatogram presents an orange stain above (xanthophyll )and a green one below (chlorophyll.)

Questions:
1.When you crush the leaves with alcohol to catch  the chlorophyll , which  method are you  using  to separate?

2. Then we filter the liquid obtained. How do you say this method? For what purpose  that?

3. Finally we do a  chromatography to separate the different pigments in the leaves. Why do the different bands appear?

4. Draw the chromatogram obtained.