Page 35 - Curriculum Visions Dynamic Book

acetone: a petroleum-based solvent.
dye: a coloured substance that will stick to
another substance, so that both appear coloured.
fertile: able to provide the nutrients needed for unrestricted plant growth.
nutrients: soluble ions that are essential to life. organic substance: a substance that contains carbon.
 The beetroot juice is added to the top of the column.
The cotton wool is still colourless, because none of the components of the beetroot juice have yet been washed through.
 The first component of the beetroot juice emerges from the base of the tube. It is a yellow substance.
 These are the first two components collected from the tube. Notice they are slightly different colours. The substance on the right is chlorophyll (the green pigment in plants), while that on the left is called xanthophyl.
Also...
The process demonstrated here is an example
of chromatography, the use of a compound that does not react, to separate out the components
of a complex substance (in this case a mixture
of vegetable dyes). A substance like aluminium oxide, used in this way, is called a stationary phase. Substances easily attach to its surface (a process called adsorption) and are also easily washed off again. Each substance “sticks” to the aluminium oxide to a different degree, so that the least firmly stuck can be washed off most easily. The next one then washes off, and so on. As a result, the various compounds making up the original substance wash out of the base of the column one at a time, and can be collected separately.
35
35