Air is a mixture of gases that surrounds Earth. It is invisible, odorless, and essential for life. Air consists mainly of nitrogen (78%), oxygen (21%), and traces of other gases like carbon dioxide and water vapor. It has various properties including being colorless, odorless, able to be felt as wind, exerting pressure, occupying space, and having mass. Air expands when heated and consists of several gases vital for sustaining life.

1. Properties of Air
Prof.Anu Swedha A
Department of Microbiology,
Justice Basheer Ahmed Sayeed College for Women,
Chennai

2. Air
 Air is something which we can only feel and not
touch.
 Air is completely invisible and inevitable.
 It plays the most important part of our life that
is being essential for breathing.
 Air is a mixture of gases, 78% nitrogen and
21% oxygen with traces of water vapor, carbon
dioxide, argon, and various other components.

3. Definition of air
 Air is a homogenous mixture of different gases like
oxygen, nitrogen, water vapor, carbon dioxide, etc.
 Air itself exists in gaseous form.
 Air can be stored and is very vital for our breathing.
 Life does not exist in outer space due to the absence
of air. The atmosphere of the earth contains air.
Different types of gases are present in the air.

4. Properties Of Air
1. Air is colorless and odorless :
 Air does not have any color of its own it is
transparent. It neither has any smell of its own. But
sometimes some gases mix with air to give us good
or bad smell.

5. 2. Air can be felt
 Air can only be felt as the wind. It cannot be seen or
tasted but can be breathed. The air that goes into
our body carries in oxygen and the air that comes
out carries out carbon dioxide gas.

6. Air exerts pressure
 Particles of airflow in all directions and force are
exerted which is called pressure. The closer we get
towards earth the atmospheric pressure increases
due to the weight of air particles.

7. Air occupies space
 Air, when blown, fills up the empty space therefore
they occupy space. You can see this in the example
of blowing a balloon. The more air you blow the more
it will expand due to the volume occupied by air.

8. Air has mass/weight
 There is a misconception that air might be a
massless object. But, the air has weight and due to
the gravitational pull of Earth, the air present at the
surface of the Earth is denser than at high altitudes.
That is why you find it difficult to breathe at higher
altitudes.

9. Air expands
 Air has a property to expand, on heating it expands
and occupies space the more it expands the thinner
it becomes.

10. Air is made up of gases
 Air consists of a number of gases like nitrogen,
oxygen, water vapor, argon, carbon dioxide, etc. The
compositions might vary according to local
conditions like volcanic eruptions, factories, and
other human activities.

11. Composition Of Air:
 1. Nitrogen: About 78% of nitrogen is present in the air. It is a very vital component of
air. It is inert in nature which is why it doesn’t affect us even though ~80% of the air we
breathe is nitrogen. It is a very important component for plants and is fixated and
recycled through the geochemical nitrogen cycle.
 2. Oxygen: About 22% of oxygen is present in the air. It is a vital component for
sustaining life on planet Earth.
 3. Argon(Ar):
 About 1% of argon is present in air. It is another inert gas. All these major gases
(nitrogen, oxygen, and argon) make up around 99.6% of dry air in the atmosphere.
 4. Other gases
 The rest 0.4% of air is covered by other minor gases like Carbon dioxide[~0.4 %],
Neon[~0.08%], Helium [~0.005%], Krypton[~0.0001%], hydrogen[0.00005%], and trace
amounts of xenon gas.
 5. Other components in the air include Sulfur dioxide, methane, ozone, nitrous
oxide, nitrogen dioxide, iodine, carbon monoxide, and ammonia