a)Carbon, because of its ability to
combine in many ways with itself and other
elements, has a central role in the chemistry of
You could do the experiment/demo of mixing concentrated sulfuric acid with granulated white sugar and put a glass beaker over it. The students will see the sugar turn black (into carbon, C) and steam being produced (H2O), showing that sugar is made up of carbon.
By extension you could burn paper or dried
bread and show that they are also made of carbon
chains. Since the students eat sugar and bread to
stay alive they too are made of those elements.
Conservation of mass.
b) Living organisms
are made of molecules largely consisting of
carbon, hydrogen, nitrogen, oxygen, phosphorous,
and sulfur. Try growing some plants form seeds
- like peas or beans- in different pots and once they have sprouted to about the same height then transplant them to some sterile sandy soil. Then water each plant the same amount. In one pot only give water, so the only elements it gets are
carbon, hydrogen and oxygen. In another pot just
add ammonia fertilizer, supplying N (nitrogen) and
in another supply sulfur and phosphor only and
finally in the last pot a balance died. This is
the usual science fair experiment but very
c) Living organisms have many
different kinds of molecules including small ones
such as water and salt, and very large ones such
as carbohydrates, fats, proteins, and DNA.
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