Experiment 12:
Air and combustion
Introduction:
In
this experiment, you show the different elements which make up air and are required
to enable a candle to stay alight.
A
soup plate
A tea-light candle
A clear glass which is taller than the candle
Ink
Water
A match
Experiment:
Materials
required:
After
a few moments, the flame goes out and the water from the plate rises up into
the glass, taking up about a fifth of the space.
Put
the candle in the center of the plate
Pour a little water into the plate. Add a few drops of ink so that the water
is easier to see
Light the candle
Then cover it with the glass
The
components of air
Air consists of oxygen (21%), nitrogen (78%), water vapour, carbon dioxide and
other gases. Nitrogen is an inert (non moving) gas which plays no part in the
process of combustion.
The candle, as it burns, uses up one part of air, called oxygen. The water,
pushed up by the pressure of the air outside, enters into the glass, taking
up the space left by the oxygen, but it cannot fill the jar completely because
the rest of the air, which is mostly nitrogen, still takes up space inside.
What
happens?
