Do red leaves also contain green pigments? Investigate it using paper chromatography.
Paper chromatography is a method of separating the components of a mixture. It uses differences in the interactions of the components with the solvent and the paper to separate them. The liquid carries the substances up the paper, separating them based on how fast they move.
To investigate if red leaves contain green pigments, take a 3 cm wide strip of chromatographic paper or filter paper. Draw a straight, horizontal line 2 cm from the bottom with a pencil. Mark a spot with the extract of red leaves at the centre of this line.
Next, take enough solvent to make a thin layer at the bottom of a container. Place the paper strip vertically into it, ensuring the lower end dips into the solvent and the solvent level is below the spot. As the solvent rises, it will carry the leaf pigments up the paper.
The different pigments will separate into different colour spots. If a green spot appears on the paper alongside other colours, it confirms the presence of green pigments in the red leaves. Note that water may not work as a solvent in every case; sometimes, a different solvent like alcohol or a mixture of solvents is needed.
Explanation
The textbook context explains paper chromatography as a separation technique based on how fast components move with a solvent up a paper strip. To investigate red leaves for green pigments, one must apply the extract to chromatographic paper and use a solvent. As the solvent rises, it separates the pigments into distinct colour spots. If green appears, green pigments are present. The context also notes that while water is a common solvent, alcohol or a mixture of solvents may be required depending on the substances being separated.
Solution Steps
Step 1: Take a 3 cm wide strip of chromatographic paper (or filter paper) and draw a straight, horizontal line 2 cm from the bottom with a pencil.
Step 2: Mark a spot with the extract of red leaves at the centre of the line.
Step 3: Add a thin layer of solvent (water or alcohol) at the bottom of a container.
Step 4: Place the paper strip vertically into the container so the lower end dips into the solvent, ensuring the solvent level is below the ink spot.
Step 5: Observe as the solvent rises; the pigments will separate into different colour spots based on how fast they move, revealing if green pigments are present.