Unfortunately, this section is only available in the e-book version of the project.

In this science experiment you can predict the colour that green leaves will turn in the fall by separating all the colour pigments contained in a green leaf, in a process called ‘chromatography’. During ‘chromatography’, the rubbing alcohol (solvent) moves up the paper by capillary action, this occurs as a result of the attraction of the alcohol molecules to the paper. As the alcohol rises through the paper, it meets and dissolves the pigment, which will then travel up the paper with the alcohol solute sample. Different compounds in the sample mixture (the pigment) travel at different rates due to competition between the paper fibres and water for the solutes.

The pigments found in leaves are used in a plant’s food making process, called ‘photosynthesis’. Different colour pigments absorb different wavelengths of light to make this process more efficient for the plant. The main pigments are ‘Chlorophyll A’ and ‘Chlorophyll B’, which causes the green colour of a leaf. Other pigments you may see are: yellow pigments (xanthophylls – Birch & Ash trees), orange pigments (carotenes – Maple trees) or Brown / Red pigment (anthocyanins – White oaks).