Page 34 - Curriculum Visions Dynamic Book
P. 34
Aluminium oxide for separating mixtures
Aluminium oxide (alumina) is one of the
most common yet overlooked of compounds.
It occurs in all of the world’s soils, combining with silicon compounds to make tiny particles of clay. Clays are important to a soil because they can hold nutrients (cations) on their surfaces, so in general a fertile soil is a soil with clay.
The way that aluminium oxide acts as a filter can be demonstrated by pouring a mixture
of dyes in solution through a tube containing aluminium oxide powder.
Most organic substances are made of a variety of compounds. Beetroot is
a good example. It is first prepared by crushing it using a pestle and mortar.
The column of aluminium oxide is prepared by filling it with acetone.
Acetone
Aluminium oxide
Cotton wool support
The beetroot juice is diluted with a liquid in which it can dissolve
(in this case acetone).
Rubber stopper with hole
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